2015-10-07 12:05:00

26 files changed, 11637 insertions, 14 deletions

diff --git a/doc/context/documents/general/manuals/luatex.pdf b/doc/context/documents/general/manuals/luatex.pdf
new file mode 100644
index 000000000..52f96d25a
--- /dev/null
+++ b/doc/context/documents/general/manuals/luatex.pdf
diff --git a/doc/context/sources/general/manuals/luatex/luatex-contents.tex b/doc/context/sources/general/manuals/luatex/luatex-contents.tex
new file mode 100644
index 000000000..f002716b1
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-contents.tex
@@ -0,0 +1,20 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-contents
+
+\starttitle[title=Contents]
+
+\start
+
+    \definecolor[maincolor][black]
+
+    \placecontent
+      [criterium=text,
+       level=subsection]
+
+\stop
+
+\stoptitle
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-enhancements.tex b/doc/context/sources/general/manuals/luatex/luatex-enhancements.tex
new file mode 100644
index 000000000..c16c66d62
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-enhancements.tex
@@ -0,0 +1,708 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-enhancements
+
+\startchapter[reference=enhancements,title={Basic \TEX\ enhancements}]
+
+\section{Introduction}
+
+From day one, \LUATEX\ has offered extra features compared to the superset of
+\PDFTEX\ and \ALEPH. That has not been limited to the possibility to execute
+\LUA\ code via \type {\directlua}, but \LUATEX\ also adds functionality via new
+\TEX-side primitives.
+
+When \LUATEX\ starts up in \quote {iniluatex} mode (\type {luatex -ini}), it
+defines only the primitive commands known by \TEX82 and the one extra command
+\type {\directlua}. As is fitting, a \LUA\ function has to be called to add the
+extra primitives to the user environment. The simplest method to get access to
+all of the new primitive commands is by adding this line to the format generation
+file:
+
+\starttyping
+\directlua { tex.enableprimitives('',tex.extraprimitives()) }
+\stoptyping
+
+But be aware that the curly braces may not have the proper \type {\catcode}
+assigned to them at this early time (giving a \quote {Missing number} error), so
+it may be needed to put these assignments before the above line:
+
+\starttyping
+\catcode `\{=1
+\catcode `\}=2
+\stoptyping
+
+More fine-grained primitives control is possible, you can look up the details in
+\in {section} [luaprimitives]. For simplicity's sake, this manual assumes that you
+have executed the \type {\directlua} command as given above.
+
+The startup behavior documented above is considered stable in the sense that
+there will not be backward|-|incompatible changes any more. However, we can
+decide to promite some primitives to the \LUATEX\ namespace. For instance, after
+version 0.80.1 we promoted some rather generic \PDFTEX\ primitives to core
+\LUATEX\ ones, and the ones inherited frome \ALEPH\ (\OMEGA) are also promoted.
+Effectively this means that we now have the \type {tex}, \type {etex}, \type
+{luatex} and \type {pdftex} (sub)sets left.
+
+\section{Version information}
+
+There are three new primitives to test the version of \LUATEX:
+
+\starttabulate[|l|p|p|]
+\NC \bf primitive           \NC \bf explanation                           \NC \bf value          \NC \NR
+\NC \type {\luatexbanner}   \NC the banner reported on the command line   \NC \luatexbanner      \NC \NR
+\NC \type {\luatexversion}  \NC a combination of major and minor number   \NC \the\luatexversion \NC \NR
+\NC \type {\luatexrevision} \NC the revision number, the current value is \NC \luatexrevision    \NC \NR
+\stoptabulate
+
+The official \LUATEX\ version is defined as follows:
+
+\startitemize
+\startitem
+    The major version is the integer result of \type {\luatexversion} divided by
+    100. The primitive is an \quote {internal variable}, so you may need to prefix
+    its use with \type {\the} depending on the context.
+\stopitem
+\startitem
+    The minor version is the two-digit result of \type {\luatexversion} modulo 100.
+\stopitem
+\startitem
+    The revision is the given by \type {\luatexrevision}. This primitive expands to
+    a positive integer.
+\stopitem
+\startitem
+    The full version number consists of the major version, minor version and
+    revision, separated by dots.
+\stopitem
+\stopitemize
+
+\section{\UNICODE\ text support}
+
+Text input and output is now considered to be \UNICODE\ text, so input characters
+can use the full range of \UNICODE\ ($2^{20}+2^{16}-1 = \hbox{0x10FFFF}$). Later
+chapters will talk of characters and glyphs. Although these are not
+interchangeable, they are closely related. During typesetting, a character is
+always converted to a suitable graphic representation of that character in a
+specific font. However, while processing a list of to|-|be|-|typeset nodes, its
+contents may still be seen as a character. Inside \LUATEX\ there is no clear
+separation between the two concepts. Because the subtype of a glyph node can be
+changed in \LUA\ it is lso up to the user.
+
+A few primitives are affected by this, all in a similar fashion: each of them has
+to accommodate for a larger range of acceptable numbers. For instance, \type
+{\char} now accepts values between~0 and $1{,}114{,}111$. This should not be a
+problem for well|-|behaved input files, but it could create incompatibilities for
+input that would have generated an error when processed by older \TEX|-|based
+engines. The affected commands with an altered initial (left of the equals sign)
+or secondary (right of the equals sign) value are: \type {\char}, \type
+{\lccode}, \type {\uccode}, \type {\catcode}, \type {\sfcode}, \type {\efcode},
+\type {\lpcode}, \type {\rpcode}, \type {\chardef}.
+
+As far as the core engine is concerned, all input and output to text files is
+\UTF-8 encoded. Input files can be pre|-|processed using the \type {reader}
+callback. This will be explained in a later chapter.
+
+Output in byte|-|sized chunks can be achieved by using characters just outside of
+the valid \UNICODE\ range, starting at the value $1{,}114{,}112$ (0x110000). When
+the time comes to print a character $c>=1{,}114{,}112$, \LUATEX\ will actually
+print the single byte corresponding to $c$ minus 1{,}114{,}112.
+
+Output to the terminal uses \type {^^} notation for the lower control range
+($c<32$), with the exception of \type {^^I}, \type {^^J} and \type {^^M}. These
+are considered \quote {safe} and therefore printed as-is.
+
+Normalization of the \UNICODE\ input can be handled by a macro package during
+callback processing (this will be explained in \in{section}[iocallback]).
+
+\section{Extended tables}
+
+All traditional \TEX\ and \ETEX\ registers can be 16-bit numbers. The affected
+commands are:
+
+\startfourcolumns
+\starttyping
+\count
+\dimen
+\skip
+\muskip
+\marks
+\toks
+\countdef
+\dimendef
+\skipdef
+\muskipdef
+\toksdef
+\insert
+\box
+\unhbox
+\unvbox
+\copy
+\unhcopy
+\unvcopy
+\wd
+\ht
+\dp
+\setbox
+\vsplit
+\stoptyping
+\stopfourcolumns
+
+The glyph properties \type {\efcode}, \type {\lpcode} and \type {\rpcode},
+introduced in \PDFTEX\ that deal with font expansion (hz) and character
+protruding, are also 16-bit. Because font memory management has been rewritten,
+these character properties are no longer shared among fonts instances that
+originate from the same metric file.
+
+\section{Attributes}
+
+\subsection{Attribute registers}
+
+Attributes are a completely new concept in \LUATEX. Syntactically, they behave a
+lot like counters: attributes obey \TEX's nesting stack and can be used after
+\type {\the} etc.\ just like the normal \type {\count} registers.
+
+\startsyntax
+\attribute <16-bit number> <optional equals> <32-bit number>!crlf
+\attributedef <csname> <optional equals> <16-bit number>
+\stopsyntax
+
+Conceptually, an attribute is either \quote {set} or \quote {unset}. Unset
+attributes have a special negative value to indicate that they are unset, that
+value is the lowest legal value: \type {-"7FFFFFFF} in hexadecimal, a.k.a.
+$-2147483647$ in decimal. It follows that the value \type {-"7FFFFFFF} cannot be
+used as a legal attribute value, but you {\it can\/} assign \type {-"7FFFFFFF} to
+\quote {unset} an attribute. All attributes start out in this \quote {unset}
+state in \INITEX.
+
+Attributes can be used as extra counter values, but their usefulness comes mostly
+from the fact that the numbers and values of all \quote {set} attributes are
+attached to all nodes created in their scope. These can then be queried from any
+\LUA\ code that deals with node processing. Further information about how to use
+attributes for node list processing from \LUA\ is given in~\in {chapter}[nodes].
+
+\subsection{Box attributes}
+
+Nodes typically receive the list of attributes that is in effect when they are
+created. This moment can be quite asynchronous. For example: in paragraph
+building, the individual line boxes are created after the \type {\par} command has
+been processed, so they will receive the list of attributes that is in effect
+then, not the attributes that were in effect in, say, the first or third line of
+the paragraph.
+
+Similar situations happen in \LUATEX\ regularly. A few of the more obvious
+problematic cases are dealt with: the attributes for nodes that are created
+during hyphenation, kerning and ligaturing borrow their attributes from their
+surrounding glyphs, and it is possible to influence box attributes directly.
+
+When you assemble a box in a register, the attributes of the nodes contained in
+the box are unchanged when such a box is placed, unboxed, or copied. In this
+respect attributes act the same as characters that have been converted to
+references to glyphs in fonts. For instance, when you use attributes to implement
+color support, each node carries information about its eventual color. In that
+case, unless you implement mechanisms that deal with it, applying a color to
+already boxed material will have no effect. Keep in mind that this
+incompatibility is mostly due to the fact that separate specials and literals are
+a more unnatural approach to colors than attributes.
+
+It is possible to fine-tune the list of attributes that are applied to a \type
+{hbox}, \type {vbox} or \type {vtop} by the use of the keyword \type {attr}. An
+example:
+
+\starttyping
+\attribute2=5
+\setbox0=\hbox {Hello}
+\setbox2=\hbox attr1=12 attr2=-"7FFFFFFF{Hello}
+\stoptyping
+
+This will set the attribute list of box~2 to $1=12$, and the attributes of box~0
+will be $2=5$. As you can see, assigning the maximum negative value causes an
+attribute to be ignored.
+
+The \type {attr} keyword(s) should come before a \type {to} or \type {spread}, if
+that is also specified.
+
+\section{\LUA\ related primitives}
+
+\subsection{\type {\directlua}}
+
+In order to merge \LUA\ code with \TEX\ input, a few new primitives are needed.
+The primitive \type {\directlua} is used to execute \LUA\ code immediately. The
+syntax is
+
+\startsyntax
+\directlua <general text>!crlf
+\directlua name <general text> <general text>!crlf
+\directlua <16-bit number> <general text>
+\stopsyntax
+
+The last \syntax {<general text>} is expanded fully, and then fed into the \LUA\
+interpreter. After reading and expansion has been applied to the \syntax
+{<general text>}, the resulting token list is converted to a string as if it was
+displayed using \type {\the\toks}. On the \LUA\ side, each \type {\directlua}
+block is treated as a separate chunk. In such a chunk you can use the \type
+{local} directive to keep your variables from interfering with those used by the
+macro package.
+
+The conversion to and from a token list means that you normally can not use \LUA\
+line comments (starting with \type {--}) within the argument. As there typically
+will be only one \quote {line} the first line comment will run on until the end
+of the input. You will either need to use \TEX|-|style line comments (starting
+with \%), or change the \TEX\ category codes locally. Another possibility is to
+say:
+
+\starttyping
+\begingroup
+\endlinechar=10
+\directlua ...
+\endgroup
+\stoptyping
+
+Then \LUA\ line comments can be used, since \TEX\ does not replace line endings
+with spaces.
+
+The \syntax {name <general text>} specifies the name of the \LUA\ chunk, mainly
+shown in the stack backtrace of error messages created by \LUA\ code. The \syntax
+{<general text>} is expanded fully, thus macros can be used to generate the chunk
+name, i.e.
+
+\starttyping
+\directlua name{\jobname:\the\inputlineno} ...
+\stoptyping
+
+to include the name of the input file as well as the input line into the chunk
+name.
+
+Likewise, the \syntax {<16-bit number>} designates a name of a \LUA\ chunk, but
+in this case the name will be taken from the \type {lua.name} array (see the
+documentation of the \type {lua} table further in this manual).
+
+The chunk name should not start with a \type {@}, or it will be displayed as a
+file name (this is a quirk in the current \LUA\ implementation).
+
+The \type {\directlua} command is expandable. Since it passes \LUA\ code to the
+\LUA\ interpreter its expansion from the \TEX\ viewpoint is usually empty.
+However, there are some \LUA\ functions that produce material to be read by \TEX,
+the so called print functions. The most simple use of these is \type
+{tex.print(<string> s)}. The characters of the string \type {s} will be placed on
+the \TEX\ input buffer, that is, \quote {before \TEX's eyes} to be read by \TEX\
+immediately. For example:
+
+\startbuffer
+\count10=20
+a\directlua{tex.print(tex.count[10]+5)}b
+\stopbuffer
+
+\typebuffer
+
+expands to
+
+\getbuffer
+
+Here is another example:
+
+\startbuffer
+$\pi = \directlua{tex.print(math.pi)}$
+\stopbuffer
+
+\typebuffer
+
+will result in
+
+\getbuffer
+
+Note that the expansion of \type {\directlua} is a sequence of characters, not of
+tokens, contrary to all \TEX\ commands. So formally speaking its expansion is
+null, but it places material on a pseudo-file to be immediately read by \TEX, as
+\ETEX's \type {\scantokens}. For a description of print functions look at \in
+{section} [sec:luaprint].
+
+Because the \syntax {<general text>} is a chunk, the normal \LUA\ error handling
+is triggered if there is a problem in the included code. The \LUA\ error messages
+should be clear enough, but the contextual information is still pretty bad.
+Often, you will only see the line number of the right brace at the end of the
+code.
+
+While on the subject of errors: some of the things you can do inside \LUA\ code
+can break up \LUATEX\ pretty bad. If you are not careful while working with the
+node list interface, you may even end up with assertion errors from within the
+\TEX\ portion of the executable.
+
+The behavior documented in the above subsection is considered stable in the sense
+that there will not be backward-incompatible changes any more.
+
+\subsection{\type {\latelua}}
+
+\type {\latelua} stores \LUA\ code in a whatsit that will be processed at the time
+of shipping out. Its intended use is a cross between \type {\pdfliteral} and
+\type {\write}. Within the \LUA\ code you can print \PDF\ statements directly to the
+\PDF\ file via \type {pdf.print}, or you can write to other output streams via
+\type {texio.write} or simply using \LUA\ I/O routines.
+
+\startsyntax
+\latelua <general text>!crlf
+\latelua name <general text> <general text>!crlf
+\latelua <16-bit number> <general text>
+\stopsyntax
+
+Expansion of macros etcetera in the final \type {<general text>} is delayed until
+just before the whatsit is executed (like in \type {\write}). With regard to \PDF\
+output stream \type {\latelua} behaves as \type {\pdfliteral page}. The \syntax {name
+<general text>} and \syntax {<16-bit number>} behave in the same way as they do
+for \type {\directlua}
+
+\subsection{\type {\luaescapestring}}
+
+This primitive converts a \TEX\ token sequence so that it can be safely used as
+the contents of a \LUA\ string: embedded backslashes, double and single quotes,
+and newlines and carriage returns are escaped. This is done by prepending an
+extra token consisting of a backslash with category code~12, and for the line
+endings, converting them to \type {n} and \type {r} respectively. The token
+sequence is fully expanded.
+
+\startsyntax
+\luaescapestring <general text>
+\stopsyntax
+
+Most often, this command is not actually the best way to deal with the
+differences between the \TEX\ and \LUA. In very short bits of \LUA\
+code it is often not needed, and for longer stretches of \LUA\ code it
+is easier to keep the code in a separate file and load it using \LUA's
+\type {dofile}:
+
+\starttyping
+\directlua { dofile('mysetups.lua') }
+\stoptyping
+
+\subsection{\type {\luafunction}}
+
+The \type {\directlua} commands involves tokenization of its argument (after
+picking up an optional name or number specification). The tokenlist is then
+converted into a string and given to \LUA\ to turn into a function that is
+called. The overhead is rather small but when you use this primitive hundreds or
+thousands of times, it can become noticeable. For this reason there is a variant
+call available: \type {\luafunction}. This command is used as follows:
+
+\starttyping
+\directlua {
+    local t = lua.get_functions_table()
+    t[1] = function() tex.print("!") end
+    t[2] = function() tex.print("?") end
+}
+
+\luafunction1
+\luafunction2
+\stoptyping
+
+Of course the functions can also be defined in a separate file. There is no limit
+on the number of functions apart from normal \LUA\ limitations. Of course there
+is the limitation of no arguments but that would involve parsing and thereby give
+no gain. The function, when called in fact gets one argument, being the index, so
+in the following example the number \type {8} gets typeset.
+
+\starttyping
+\directlua {
+    local t = lua.get_functions_table()
+    t[8] = function(slot) tex.print(slot) end
+}
+\stoptyping
+
+\section{\type {\clearmarks}}
+
+This primitive complements the \ETEX\ mark primitives and clears a mark class
+completely, resetting all three connected mark texts to empty. It is an
+immediate command.
+
+\startsyntax
+\clearmarks <16-bit number>
+\stopsyntax
+
+\section{\type {\noligs} and \type {\nokerns}}
+
+These primitives prohibit ligature and kerning insertion at the time when the
+initial node list is built by \LUATEX's main control loop. They are part of a
+temporary trick and will be removed in the near future. For now, you need to
+enable these primitives when you want to do node list processing of \quote
+{characters}, where \TEX's normal processing would get in the way.
+
+\startsyntax
+\noligs <integer>!crlf
+\nokerns <integer>
+\stopsyntax
+
+These primitives can now be implemented by overloading the ligature building and
+kerning functions, i.e.\ by assigning dummy functions to their associated
+callbacks.
+
+\section{\type {\formatname}}
+
+The \type {\formatname} syntax is identical to \type {\jobname}. In \INITEX, the
+expansion is empty. Otherwise, the expansion is the value that \type {\jobname} had
+during the \INITEX\ run that dumped the currently loaded format.
+
+\section{\type {\scantextokens}}
+
+The syntax of \type {\scantextokens} is identical to \type {\scantokens}. This
+primitive is a slightly adapted version of \ETEX's \type {\scantokens}. The
+differences are:
+
+\startitemize
+\startitem
+    The last (and usually only) line does not have a \type {\endlinechar}
+    appended.
+\stopitem
+\startitem
+    \type {\scantextokens} never raises an EOF error, and it does not execute
+    \type {\everyeof} tokens.
+\stopitem
+\startitem
+    The \quote{\unknown\ while end of file \unknown} error tests are not
+    executed, allowing the expansion to end on a different grouping level or
+    while a conditional is still incomplete.
+\stopitem
+\stopitemize
+
+\section {Alignments}
+
+\subsection{\tex {alignmark}}
+
+This primitive duplicates the functionality of \type {#} inside alignment
+preambles.
+
+\subsection{\tex {aligntab}}
+
+This primitive duplicates the functionality of \type {&} inside alignments and
+preambles.
+
+\section{Catcode tables}
+
+Catcode tables are a new feature that allows you to switch to a predefined
+catcode regime in a single statement. You can have a practically unlimited number
+of different tables. This subsystem is backward compatible: if you never use the
+following commands, your document will not notice any difference in behavior
+compared to traditional \TEX. The contents of each catcode table is independent
+from any other catcode tables, and their contents is stored and retrieved from
+the format file.
+
+\subsection{\type {\catcodetable}}
+
+\startsyntax
+\catcodetable <15-bit number>
+\stopsyntax
+
+The primitive \type {\catcodetable} switches to a different catcode table. Such a
+table has to be previously created using one of the two primitives below, or it
+has to be zero. Table zero is initialized by \INITEX.
+
+\subsection{\type {\initcatcodetable}}
+
+\startsyntax
+\initcatcodetable <15-bit number>
+\stopsyntax
+
+The primitive \type {\initcatcodetable} creates a new table with catcodes identical
+to those defined by \INITEX:
+
+\starttabulate[|r|l|l|l|l|]
+\NC  0 \NC \type {\letterbackslash}       \NC         \NC \type {escape}       \NC\NR
+\NC  5 \NC \type {\letterhat\letterhat M} \NC return  \NC \type {car_ret}      \NC (this name may change) \NC\NR
+\NC  9 \NC \type {\letterhat\letterhat @} \NC null    \NC \type {ignore}       \NC\NR
+\NC 10 \NC \type {<space>}                \NC space   \NC \type {spacer}       \NC\NR
+\NC 11 \NC \type {a} -- \type {z}         \NC         \NC \type {letter}       \NC\NR
+\NC 11 \NC \type {A} -- \type {Z}         \NC         \NC \type {letter}       \NC\NR
+\NC 12 \NC everything else                \NC         \NC \type {other}        \NC\NR
+\NC 14 \NC \type {\letterpercent}         \NC         \NC \type {comment}      \NC\NR
+\NC 15 \NC \type {\letterhat\letterhat ?} \NC delete  \NC \type {invalid_char} \NC\NR
+\stoptabulate
+
+The new catcode table is allocated globally: it will not go away after the
+current group has ended. If the supplied number is identical to the currently
+active table, an error is raised.
+
+\subsection{\type {\savecatcodetable}}
+
+\startsyntax
+\savecatcodetable <15-bit number>
+\stopsyntax
+
+\type {\savecatcodetable} copies the current set of catcodes to a new table with
+the requested number. The definitions in this new table are all treated as if
+they were made in the outermost level.
+
+The new table is allocated globally: it will not go away after the current group
+has ended. If the supplied number is the currently active table, an error is
+raised.
+
+\section{Suppressing errors}
+
+\subsection{\type {\suppressfontnotfounderror}}
+
+\startsyntax
+\suppressfontnotfounderror = 1
+\stopsyntax
+
+If this new integer parameter is non|-|zero, then \LUATEX\ will not complain
+about font metrics that are not found. Instead it will silently skip the font
+assignment, making the requested csname for the font \type {\ifx} equal to
+\type {\nullfont}, so that it can be tested against that without bothering the user.
+
+\subsection{\type {\suppresslongerror}}
+
+\startsyntax
+\suppresslongerror = 1
+\stopsyntax
+
+If this new integer parameter is non|-|zero, then \LUATEX\ will not complain
+about \type {\par} commands encountered in contexts where that is normally
+prohibited (most prominently in the arguments of non-long macros).
+
+\subsection{\type {\suppressifcsnameerror}}
+
+\startsyntax
+\suppressifcsnameerror = 1
+\stopsyntax
+
+If this new integer parameter is non|-|zero, then \LUATEX\ will not complain
+about non-expandable commands appearing in the middle of a \type {\ifcsname}
+expansion. Instead, it will keep getting expanded tokens from the input until it
+encounters an \type {\endcsname} command. Use with care! This command is
+experimental: if the input expansion is unbalanced wrt. \type {\csname} \ldots
+\type {\endcsname} pairs, the \LUATEX\ process may hang indefinitely.
+
+\subsection{\type {\suppressoutererror}}
+
+\startsyntax
+\suppressoutererror = 1
+\stopsyntax
+
+If this new integer parameter is non|-|zero, then \LUATEX\ will not complain
+about \type {\outer} commands encountered in contexts where that is normally
+prohibited.
+
+\subsection{\type {\suppressmathparerror}}
+
+The following setting will permit \par tokens in a math formula:
+
+\startsyntax
+\suppressmathparerror = 1
+\stopsyntax
+
+So, the next code is valid then:
+
+\starttyping
+$ x + 1 =
+
+a $
+\stoptyping
+
+\section{\type {\matheqnogapstep}}
+
+By default \TEX\ will add one quad between the equation and the number. This is
+hardcoded. A new primitive can control this:
+
+\startsyntax
+\matheqnogapstep = 1000
+\stopsyntax
+
+Because a math quad from the math text font is used instead of a dimension, we
+use a step to control the size. A value of zero will suppress the gap. The step
+is divided by 1000 which is the usual way to mimmick floating point factors in
+\TEX.
+
+\section{\type {\outputbox}}
+
+\startsyntax
+\outputbox = 65535
+\stopsyntax
+
+This new integer parameter allows you to alter the number of the box that will be
+used to store the page sent to the output routine. Its default value is 255, and
+the acceptable range is from 0 to 65535.
+
+\section{\type {\fontid}}
+
+\startsyntax
+\fontid\font
+\stopsyntax
+
+This primitive expands into a number. It is not a register so there is no need to
+prefix with \type {\number} (and using \type {\the} gives an error). The currently
+used font id is \fontid\font. Here are some more:
+
+\starttabulate[|l|c|]
+\NC \type {\bf} \NC \bf \fontid\font \NC \NR
+\NC \type {\it} \NC \it \fontid\font \NC \NR
+\NC \type {\bi} \NC \bi \fontid\font \NC \NR
+\stoptabulate
+
+These numbers depend on the macro package used because each one has its own way
+of dealing with fonts. They can also differ per run, as they can depend on the
+order of loading fonts. For instance, when in \CONTEXT\ virtual math \UNICODE\
+fonts are used, we can easily get over a hundred ids in use. Not all ids have to
+be bound to a real font, after all it's just a number.
+
+\section{\type {\gleaders}}
+
+This type of leaders is anchored to the origin of the box to be shipped out. So
+they are like normal \type {\leaders} in that they align nicely, except that the
+alignment is based on the {\it largest\/} enclosing box instead of the {\it
+smallest\/}. The \type {g} stresses this global nature.
+
+\section{\type {\Uchar}}
+
+The expandable command \type {\Uchar} reads a number between~0 and $1{,}114{,}111$
+and expands to the associated \UNICODE\ character.
+
+\section{\type {\hyphenationmin}}
+
+This primitive can be used to set the minimal word length, so setting it to a value
+of~$5$ means that only words of 6 characters and more will be hyphenated, of course
+within the constraints of the \type {\lefthyphenmin} and \type {\righthyphenmin}
+values (as stored in the glyph node). This primitive accepts a number and stores
+the value with the language.
+
+\section{Debugging}
+
+If \type {\tracingonline} is larger than~2, the node list display will also print
+the node number of the nodes.
+
+\section{Images and Forms}
+
+\LUATEX\ accepts optional dimension parameters for \type {\pdfrefximage} and
+\type {\pdfrefxform} in the same format as for \type {\pdfximage}. With images,
+these dimensions are then used instead of the ones given to \type {\pdfximage}
+but the original dimensions are not overwritten, so that a \type {\pdfrefximage}
+without dimensions still provides the image with dimensions defined by \type
+{\pdfximage}. These optional parameters are not implemented for \type
+{\pdfxform}.
+
+\starttyping
+\pdfrefximage width 20mm height 10mm depth 5mm \pdflastximage
+\pdfrefxform  width 20mm height 10mm depth 5mm \pdflastxform
+\stoptyping
+
+\section{File syntax}
+
+\LUATEX\ will accept a braced argument as a file name:
+
+\starttyping
+\input {plain}
+\openin 0 {plain}
+\stoptyping
+
+This allows for embedded spaces, without the need for double quotes. Macro
+expansion takes place inside the argument.
+
+\section{Font syntax}
+
+\LUATEX\ will accept a braced argument as a font name:
+
+\starttyping
+\font\myfont = {cmr10}
+\stoptyping
+
+This allows for embedded spaces, without the need for double quotes. Macro
+expansion takes place inside the argument.
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-fonts.tex b/doc/context/sources/general/manuals/luatex/luatex-fonts.tex
new file mode 100644
index 000000000..8ea4058a6
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-fonts.tex
@@ -0,0 +1,618 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-fonts
+
+\startchapter[reference=fonts,title={Font structure}]
+
+All \TEX\ fonts are represented to \LUA\ code as tables, and internally as
+\CCODE~structures. All keys in the table below are saved in the internal font
+structure if they are present in the table returned by the \type {define_font}
+callback, or if they result from the normal \TFM|/|\VF\ reading routines if there
+is no \type {define_font} callback defined.
+
+The column \quote {from \VF} means that this key will be created by the \type
+{font.read_vf()} routine, \quote {from \TFM} means that the key will be created
+by the \type {font.read_tfm()} routine, and \quote{used} means whether or not
+the \LUATEX\ engine itself will do something with the key.
+
+The top|-|level keys in the table are as follows:
+
+\starttabulate[|Tl|l|l|l|l|p|]
+\NC \ssbf key  \NC \bf from vf \NC \bf from tfm \NC \bf used\NC \bf value type \NC
+    \bf description
+\NC \NR
+\NC name               \NC yes      \NC yes      \NC yes \NC string \NC
+    metric (file) name
+\NC \NR
+\NC area               \NC no       \NC yes      \NC yes \NC string \NC
+    (directory) location, typically empty
+\NC \NR
+\NC used               \NC no       \NC yes      \NC yes \NC boolean\NC
+    used already? (initial: false)
+\NC \NR
+\NC characters         \NC yes      \NC yes      \NC yes \NC table  \NC
+    the defined glyphs of this font
+\NC \NR
+\NC checksum           \NC yes      \NC yes      \NC no  \NC number \NC
+    default: 0
+\NC \NR
+\NC designsize         \NC no       \NC yes      \NC yes \NC number \NC
+    expected size (default: 655360 == 10pt)
+\NC \NR
+\NC direction          \NC no       \NC yes      \NC yes \NC number \NC
+    default: 0 (TLT)
+\NC \NR
+\NC encodingbytes      \NC no       \NC no       \NC yes \NC number \NC
+    default: depends on \type {format}
+\NC \NR
+\NC encodingname       \NC no       \NC no       \NC yes \NC string \NC
+    encoding name
+\NC \NR
+\NC fonts              \NC yes      \NC no       \NC yes \NC table  \NC
+    locally used fonts
+\NC \NR
+\NC psname             \NC no       \NC no       \NC yes \NC string \NC
+    actual (\POSTSCRIPT) name (this is the PS fontname in the incoming font
+    source, also used as fontname identifier in the \PDF\ output, new in 0.43)
+\NC \NR
+\NC fullname           \NC no       \NC no       \NC yes \NC string \NC
+    output font name, used as a fallback in the \PDF\ output
+    if the psname is not set
+\NC \NR
+\NC header             \NC yes      \NC no       \NC no  \NC string \NC
+    header comments, if any
+\NC \NR
+\NC hyphenchar         \NC no       \NC no       \NC yes \NC number \NC
+    default: TeX's \type {\hyphenchar}
+\NC \NR
+\NC parameters         \NC no       \NC yes      \NC yes \NC hash   \NC
+    default: 7 parameters, all zero
+\NC \NR
+\NC size               \NC no       \NC yes      \NC yes \NC number \NC
+    loaded (at) size. (default: same as designsize)
+\NC \NR
+\NC skewchar           \NC no       \NC no       \NC yes \NC number \NC
+    default: TeX's \type {\skewchar}
+\NC \NR
+\NC type               \NC yes      \NC no       \NC yes \NC string \NC
+    basic type of this font
+\NC \NR
+\NC format             \NC no       \NC no       \NC yes \NC string \NC
+    disk format type
+\NC \NR
+\NC embedding          \NC no       \NC no       \NC yes \NC string \NC
+    \PDF\ inclusion
+\NC \NR
+\NC filename           \NC no       \NC no       \NC yes \NC string \NC
+    disk file name
+\NC \NR
+\NC tounicode          \NC no       \NC yes      \NC yes \NC number \NC
+    if 1, \LUATEX\ assumes per-glyph tounicode entries are
+    present in the font
+\NC \NR
+\NC stretch            \NC no       \NC no       \NC yes \NC number \NC
+    the \quote {stretch} value from \type {\expandglyphsinfont}
+\NC \NR
+\NC shrink             \NC no       \NC no       \NC yes \NC number \NC
+    the \quote {shrink} value from \type {\expandglyphsinfont}
+\NC \NR
+\NC step               \NC no       \NC no       \NC yes \NC number \NC
+    the \quote {step} value from \type {\expandglyphsinfont}
+\NC \NR
+\NC auto_expand        \NC no       \NC no       \NC yes \NC boolean\NC
+    the \quote {autoexpand} keyword from\crlf \type {\expandglyphsinfont}
+\NC \NR
+\NC expansion_factor   \NC no       \NC no       \NC no  \NC number \NC
+    the actual expansion factor of an expanded font
+\NC \NR
+\NC attributes         \NC no       \NC no       \NC yes \NC string \NC
+    the \type {\pdffontattr}
+\NC \NR
+\NC cache              \NC no       \NC no       \NC yes \NC string \NC
+    this key controls caching of the lua table on the \type {tex} end. \type {yes}:
+    use a reference to the table that is passed to \LUATEX\ (this is the
+    default). \type {no}: don't store the table reference, don't cache any lua
+    data for this font. \type {renew}: don't store the table reference, but save a
+    reference to the table that is created at the first access to one of its
+    fields in font.fonts. (new in 0.40.0, before that caching was always
+    \type {yes}). Note: the saved reference is thread-local, so be careful when
+    you are using coroutines: an error will be thrown if the table has been
+    cached in one thread, but you reference it from another thread ($\approx$
+    coroutine)
+\NC \NR
+\NC nomath              \NC no       \NC no       \NC yes \NC boolean\NC
+    this key allows a minor speedup for text fonts. if it is present and true,
+    then \LUATEX\ will not check the character enties for math-specific keys.
+\NC \NR
+\NC slant               \NC no       \NC no       \NC yes \NC number \NC
+    This has the same semantics as the \type {SlantFont} operator in font map
+    files.
+\NC \NR
+\NC extent              \NC no       \NC no       \NC yes \NC number \NC
+    This has the same semantics as the \type {ExtendFont} operator in font map
+    files.
+\NC \NR
+\stoptabulate
+
+The key \type {name} is always required. The keys \type {stretch}, \type
+{shrink}, \type {step} and optionally \type {auto_expand} only have meaning when
+used together: they can be used to replace a post|-|loading \type
+{\expandglyphsinfont} command. The \type {expansion_factor} is value that can be
+present inside a font in \type {font.fonts}. It is the actual expansion factor (a
+value between \type {-shrink} and \type {stretch}, with step \type {step}) of a
+font that was automatically generated by the font expansion algorithm. The key
+\type  {attributes} can be used to replace \type {\pdffontattr}. The key \type {used}
+is set by the engine when a font is actively in use, this makes sure that the
+font's definition is written to the output file (\DVI\ or \PDF). The \TFM\ reader
+sets it to false. The \type {direction} is a number signalling the \quote
+{normal} direction for this font. There are sixteen possibilities:
+
+\starttabulate[|Tc|c|c|c|]
+\NC \ssbf number \NC \bf meaning \NC \bf number \NC \bf meaning \NC\NR
+\NC 0            \NC LT          \NC 8          \NC TT          \NC\NR
+\NC 1            \NC LL          \NC 9          \NC TL          \NC\NR
+\NC 2            \NC LB          \NC 10         \NC TB          \NC\NR
+\NC 3            \NC LR          \NC 11         \NC TR          \NC\NR
+\NC 4            \NC RT          \NC 12         \NC BT          \NC\NR
+\NC 5            \NC RL          \NC 13         \NC BL          \NC\NR
+\NC 6            \NC RB          \NC 14         \NC BB          \NC\NR
+\NC 7            \NC RR          \NC 15         \NC BR          \NC\NR
+\stoptabulate
+
+These are \OMEGA|-|style direction abbreviations: the first character indicates
+the \quote {first} edge of the character glyphs (the edge that is seen first in
+the writing direction), the second the \quote {top} side.
+
+The \type {parameters} is a hash with mixed key types. There are seven possible
+string keys, as well as a number of integer indices (these start from 8 up). The
+seven strings are actually used instead of the bottom seven indices, because that
+gives a nicer user interface.
+
+The names and their internal remapping are:
+
+\starttabulate[|lT|c|]
+\NC \ssbf name    \NC \bf internal remapped number \NC\NR
+\NC slant         \NC 1 \NC\NR
+\NC space         \NC 2 \NC\NR
+\NC space_stretch \NC 3 \NC\NR
+\NC space_shrink  \NC 4 \NC\NR
+\NC x_height      \NC 5 \NC\NR
+\NC quad          \NC 6 \NC\NR
+\NC extra_space   \NC 7 \NC\LR
+\stoptabulate
+
+The keys \type {type}, \type {format}, \type {embedding}, \type {fullname} and
+\type {filename} are used to embed \OPENTYPE\ fonts in the result \PDF.
+
+The \type {characters} table is a list of character hashes indexed by an integer
+number. The number is the \quote {internal code} \TEX\ knows this character by.
+
+Two very special string indexes can be used also: \type {left_boundary} is a
+virtual character whose ligatures and kerns are used to handle word boundary
+processing. \type {right_boundary} is similar but not actually used for anything
+(yet!).
+
+Other index keys are ignored.
+
+Each character hash itself is a hash. For example, here is the character \quote
+{f} (decimal 102) in the font cmr10 at 10 points:
+
+\starttyping
+[102] = {
+    ['width'] = 200250,
+    ['height'] = 455111,
+    ['depth'] = 0,
+    ['italic'] = 50973,
+    ['kerns'] = {
+        [63] = 50973,
+        [93] = 50973,
+        [39] = 50973,
+        [33] = 50973,
+        [41] = 50973
+    },
+    ['ligatures'] = {
+        [102] = {
+            ['char'] = 11,
+            ['type'] = 0
+        },
+        [108] = {
+            ['char'] = 13,
+            ['type'] = 0
+        },
+        [105] = {
+            ['char'] = 12,
+            ['type'] = 0
+        }
+    }
+}
+\stoptyping
+
+The following top|-|level keys can be present inside a character hash:
+
+\starttabulate[|lT|c|c|c|l|p|]
+\NC \ssbf key        \NC \bf from vf \NC \bf from tfm \NC \bf used \NC \bf value type \NC \bf description \NC\NR
+\NC width            \NC yes         \NC yes          \NC yes      \NC number         \NC character's width, in sp (default 0) \NC\NR
+\NC height           \NC no          \NC yes          \NC yes      \NC number         \NC character's height, in sp (default 0) \NC\NR
+\NC depth            \NC no          \NC yes          \NC yes      \NC number         \NC character's depth, in sp (default 0) \NC\NR
+\NC italic           \NC no          \NC yes          \NC yes      \NC number         \NC character's italic correction, in sp (default zero) \NC\NR
+\NC top_accent       \NC no          \NC no           \NC maybe    \NC number         \NC character's top accent alignment place, in sp (default zero) \NC\NR
+\NC bot_accent       \NC no          \NC no           \NC maybe    \NC number         \NC character's bottom accent alignment place, in sp (default zero) \NC\NR
+\NC left_protruding  \NC no          \NC no           \NC maybe    \NC number         \NC character's \type {\lpcode} \NC\NR
+\NC right_protruding \NC no          \NC no           \NC maybe    \NC number         \NC character's \type {\rpcode} \NC\NR
+\NC expansion_factor \NC no          \NC no           \NC maybe    \NC number         \NC character's \type {\efcode} \NC\NR
+\NC tounicode        \NC no          \NC no           \NC maybe    \NC string         \NC character's Unicode equivalent(s), in UTF-16BE hexadecimal format\NC\NR
+\NC next             \NC no          \NC yes          \NC yes      \NC number         \NC the \quote{next larger} character index \NC\NR
+\NC extensible       \NC no          \NC yes          \NC yes      \NC table          \NC the constituent parts of an extensible recipe \NC\NR
+\NC vert_variants    \NC no          \NC no           \NC yes      \NC table          \NC constituent parts of a vertical variant set\NC \NR
+\NC horiz_variants   \NC no          \NC no           \NC yes      \NC table          \NC constituent parts of a horizontal variant set\NC \NR
+\NC kerns            \NC no          \NC yes          \NC yes      \NC table          \NC kerning information \NC\NR
+\NC ligatures        \NC no          \NC yes          \NC yes      \NC table          \NC ligaturing information \NC\NR
+\NC commands         \NC yes         \NC no           \NC yes      \NC array          \NC virtual font commands \NC\NR
+\NC name             \NC no          \NC no           \NC no       \NC string         \NC the character (\POSTSCRIPT) name \NC\NR
+\NC index            \NC no          \NC no           \NC yes      \NC number         \NC the (\OPENTYPE\ or \TRUETYPE) font glyph index \NC\NR
+\NC used             \NC no          \NC yes          \NC yes      \NC boolean        \NC typeset already (default: false)? \NC\NR
+\NC mathkern         \NC no          \NC no           \NC yes      \NC table          \NC math cut-in specifications \NC\NR
+\stoptabulate
+
+The values of \type {top_accent}, \type {bot_accent} and \type {mathkern} are
+used only for math accent and superscript placement, see the \at {math chapter}
+[math] in this manual for details.
+
+The values of \type {left_protruding} and \type {right_protruding} are used only
+when \type {\protrudechars} is non-zero.
+
+Whether or not \type {expansion_factor} is used depends on the font's global
+expansion settings, as well as on the value of \type {\adjustspacing}.
+
+The usage of \type {tounicode} is this: if this font specifies a \type
+{tounicode=1} at the top level, then \LUATEX\ will construct a \type {/ToUnicode}
+entry for the \PDF\ font (or font subset) based on the character|-|level \type
+{tounicode} strings, where they are available. If a character does not have a
+sensible \UNICODE\ equivalent, do not provide a string either (no empty strings).
+
+If the font-level \type {tounicode} is not set, then \LUATEX\ will build up \type
+{/ToUnicode} based on the \TEX\ code points you used, and any character-level
+\type {tounicodes} will be ignored. {\it At the moment, the string format is
+exactly the format that is expected by Adobe \CMAP\ files (\UTF-16BE in
+hexadecimal encoding), minus the enclosing angle brackets. This may change in the
+future.} Small example: the \type {tounicode} for a \type {fi} ligature would be
+\type {00660069}.
+
+The presence of \type {extensible} will overrule \type {next}, if that is also
+present. It in in turn can be overruled by \type {vert_variants}.
+
+The \type {extensible} table is very simple:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf description                    \NC\NR
+\NC top       \NC number   \NC \quote{top} character index        \NC\NR
+\NC mid       \NC number   \NC \quote{middle} character index     \NC\NR
+\NC bot       \NC number   \NC \quote{bottom} character index     \NC\NR
+\NC rep       \NC number   \NC \quote{repeatable} character index \NC\NR
+\stoptabulate
+
+The \type {horiz_variants} and \type {vert_variants} are arrays of components.
+Each of those components is itself a hash of up to five keys:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC\NR
+\NC glyph     \NC number   \NC The character index (note that this is an encoding number, not a name). \NC \NR
+\NC extender  \NC number   \NC One (1) if this part is repeatable, zero (0) otherwise. \NC \NR
+\NC start     \NC number   \NC Maximum overlap at the starting side (in scaled points). \NC \NR
+\NC end       \NC number   \NC Maximum overlap at the ending side (in scaled points). \NC \NR
+\NC advance   \NC number   \NC Total advance width of this item (can be zero or missing,
+                               then the natural size of the glyph for character \type {component}
+                               is used). \NC \NR
+\stoptabulate
+
+The \type {kerns} table is a hash indexed by character index (and \quote
+{character index} is defined as either a non|-|negative integer or the string
+value \type {right_boundary}), with the values the kerning to be applied, in
+scaled points.
+
+The \type {ligatures} table is a hash indexed by character index (and \quote
+{character index} is defined as either a non|-|negative integer or the string
+value \type {right_boundary}), with the values being yet another small hash, with
+two fields:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf description \NC \NR
+\NC type      \NC number   \NC the type of this ligature command, default 0 \NC \NR
+\NC char      \NC number   \NC the character index of the resultant ligature \NC \NR
+\stoptabulate
+
+The \type {char} field in a ligature is required.
+
+The \type {type} field inside a ligature is the numerical or string value of one
+of the eight possible ligature types supported by \TEX. When \TEX\ inserts a new
+ligature, it puts the new glyph in the middle of the left and right glyphs. The
+original left and right glyphs can optionally be retained, and when at least one
+of them is kept, it is also possible to move the new \quote {insertion point}
+forward one or two places. The glyph that ends up to the right of the insertion
+point will become the next \quote {left}.
+
+\starttabulate[|l|c|l|l|]
+\NC \bf textual (Knuth) \NC \bf number \NC \bf string    \NC result \NC\NR
+\NC l + r =: n          \NC 0          \NC \type {=:}     \NC \|n    \NC\NR
+\NC l + r =:\| n        \NC 1          \NC \type {=:|}    \NC \|nr   \NC\NR
+\NC l + r \|=: n        \NC 2          \NC \type {|=:}    \NC \|ln   \NC\NR
+\NC l + r \|=:\| n      \NC 3          \NC \type {|=:|}   \NC \|lnr  \NC\NR
+\NC l + r  =:\|\> n     \NC 5          \NC \type {=:|>}   \NC n\|r   \NC\NR
+\NC l + r \|=:\> n      \NC 6          \NC \type {|=:>}   \NC l\|n   \NC\NR
+\NC l + r \|=:\|\> n    \NC 7          \NC \type {|=:|>}  \NC l\|nr  \NC\NR
+\NC l + r \|=:\|\>\> n  \NC 11         \NC \type {|=:|>>} \NC ln\|r  \NC\NR
+\stoptabulate
+
+The default value is~0, and can be left out. That signifies a \quote {normal}
+ligature where the ligature replaces both original glyphs. In this table the~\|
+indicates the final insertion point.
+
+The \type {commands} array is explained below.
+
+\section {Real fonts}
+
+Whether or not a \TEX\ font is a \quote {real} font that should be written to the
+\PDF\ document is decided by the \type {type} value in the top|-|level font
+structure. If the value is \type {real}, then this is a proper font, and the
+inclusion mechanism will attempt to add the needed font object definitions to the
+\PDF.
+
+Values for \type {type}:
+
+\starttabulate[|Tl|p|]
+\NC \ssbf value \NC \bf description        \NC\NR
+\NC real        \NC this is a base font    \NC\NR
+\NC virtual     \NC this is a virtual font \NC\NR
+\stoptabulate
+
+The actions to be taken depend on a number of different variables:
+
+\startitemize[packed]
+\startitem
+    Whether the used font fits in an 8-bit encoding scheme or not.
+\stopitem
+\startitem
+    The type of the disk font file.
+\stopitem
+\startitem
+    The level of embedding requested.
+\stopitem
+\stopitemize
+
+A font that uses anything other than an 8-bit encoding vector has to be written
+to the \PDF\ in a different way.
+
+The rule is: if the font table has \type {encodingbytes} set to~2, then this is a
+wide font, in all other cases it isn't. The value~2 is the default for \OPENTYPE\
+and \TRUETYPE\ fonts loaded via \LUA. For \TYPEONE\ fonts, you have to set \type
+{encodingbytes} to~2 explicitly. For \PK\ bitmap fonts, wide font encoding is not
+supported at all.
+
+If no special care is needed, \LUATEX\ currently falls back to the
+mapfile|-|based solution used by \PDFTEX\ and \DVIPS. This behavior will be
+removed in the future, when the existing code becomes integrated in the new
+subsystem.
+
+But if this is a \quote {wide} font, then the new subsystem kicks in, and some
+extra fields have to be present in the font structure. In this case, \LUATEX\
+does not use a map file at all.
+
+The extra fields are: \type {format}, \type {embedding}, \type {fullname}, \type
+{cidinfo} (as explained above), \type {filename}, and the \type {index} key in
+the separate characters.
+
+Values for \type {format} are:
+
+\starttabulate[|Tl|p|]
+\NC \ssbf value \NC \bf description                                           \NC \NR
+\NC type1       \NC this is a \POSTSCRIPT\ \TYPEONE\ font                     \NC \NR
+\NC type3       \NC this is a bitmapped (\PK) font                            \NC \NR
+\NC truetype    \NC this is a \TRUETYPE\ or \TRUETYPE|-|based \OPENTYPE\ font \NC \NR
+\NC opentype    \NC this is a \POSTSCRIPT|-|based \OPENTYPE\ font             \NC \NR
+\stoptabulate
+
+\type {type3} fonts are provided for backward compatibility only, and do not
+support the new wide encoding options.
+
+Values for \type {embedding} are:
+
+\starttabulate[|Tl|p|]
+\NC \ssbf value \NC \bf description \NC \NR
+\NC no          \NC don't embed the font at all \NC \NR
+\NC subset      \NC include and atttempt to subset the font \NC \NR
+\NC full        \NC include this font in its entirety \NC \NR
+\stoptabulate
+
+It is not possible to artificially modify the transformation matrix
+for the font at the moment.
+
+The other fields are used as follows: The \type {fullname} will be the
+\POSTSCRIPT|/|\PDF\ font name. The \type {cidinfo} will be used as the character
+set (the CID \type {/Ordering} and \type {/Registry} keys). The \type {filename}
+points to the actual font file. If you include the full path in the \type
+{filename} or if the file is in the local directory, \LUATEX\ will run a little
+bit more efficient because it will not have to re|-|run the \type {find_xxx_file}
+callback in that case.
+
+Be careful: when mixing old and new fonts in one document, it is possible to
+create \POSTSCRIPT\ name clashes that can result in printing errors. When this
+happens, you have to change the \type {fullname} of the font.
+
+Typeset strings are written out in a wide format using 2~bytes per glyph, using
+the \type {index} key in the character information as value. The overall effect
+is like having an encoding based on numbers instead of traditional (\POSTSCRIPT)
+name|-|based reencoding. The way to get the correct \type {index} numbers for
+\TYPEONE\ fonts is by loading the font via \type {fontloader.open}; use the table
+indices as \type {index} fields.
+
+This type of reencoding means that there is no longer a clear connection between
+the text in your input file and the strings in the output \PDF\ file. Dealing
+with this is high on the agenda.
+
+\section[virtualfonts]{Virtual fonts}
+
+You have to take the following steps if you want \LUATEX\ to treat the returned
+table from \type {define_font} as a virtual font:
+
+\startitemize[packed]
+\startitem
+    Set the top|-|level key \type {type} to \type {virtual}.
+\stopitem
+\startitem
+    Make sure there is at least one valid entry in \type {fonts} (see below).
+\stopitem
+\startitem
+    Give a \type {commands} array to every character (see below).
+\stopitem
+\stopitemize
+
+The presence of the toplevel \type {type} key with the specific value \type
+{virtual} will trigger handling of the rest of the special virtual font fields in
+the table, but the mere existence of 'type' is enough to prevent \LUATEX\ from
+looking for a virtual font on its own.
+
+Therefore, this also works \quote {in reverse}: if you are absolutely certain
+that a font is not a virtual font, assigning the value \type {base} or \type
+{real} to \type {type} will inhibit \LUATEX\ from looking for a virtual font
+file, thereby saving you a disk search.
+
+The \type {fonts} is another \LUA\ array. The values are one- or two|-|key
+hashes themselves, each entry indicating one of the base fonts in a virtual font.
+In case your font is referring to itself, you can use the \type {font.nextid()}
+function which returns the index of the next to be defined font which is probably
+the currently defined one.
+
+An example makes this easy to understand
+
+\starttyping
+fonts = {
+    { name = 'ptmr8a', size = 655360 },
+    { name = 'psyr', size = 600000 },
+    { id = 38 }
+}
+\stoptyping
+
+says that the first referenced font (index 1) in this virtual font is \type
+{ptrmr8a} loaded at 10pt, and the second is \type {psyr} loaded at a little over
+9pt. The third one is previously defined font that is known to \LUATEX\ as fontid
+\quote {38}.
+
+The array index numbers are used by the character command definitions that are
+part of each character.
+
+The \type {commands} array is a hash where each item is another small array,
+with the first entry representing a command and the extra items being the
+parameters to that command. The allowed commands and their arguments are:
+
+\starttabulate[|Tl|l|l|p|]
+\NC \ssbf command name  \NC \bf arguments \NC \bf arg type \NC \bf description \NC\NR
+\NC font              \NC 1         \NC number    \NC select a new font from the local \type {fonts} table\NC\NR
+\NC char              \NC 1         \NC number    \NC typeset this character number from the current font,
+                                                      and move right by the character's width\NC\NR
+\NC node              \NC 1         \NC node      \NC output this node (list), and move right
+                                                      by the width of this list\NC\NR
+\NC slot              \NC 2         \NC number    \NC a shortcut for the combination of a font and char command\NC\NR
+\NC push              \NC 0         \NC           \NC save current position\NC\NR
+\NC nop               \NC 0         \NC           \NC do nothing \NC\NR
+\NC pop               \NC 0         \NC           \NC pop position \NC\NR
+\NC rule              \NC 2         \NC 2 numbers \NC output a rule $ht*wd$, and move right.\NC\NR
+\NC down              \NC 1         \NC number    \NC move down on the page\NC\NR
+\NC right             \NC 1         \NC number    \NC move right on the page\NC\NR
+\NC special           \NC 1         \NC string    \NC output a \type {\special} command\NC\NR
+\NC lua               \NC 1         \NC string    \NC execute a \LUA\ script (at \type {\latelua} time)\NC\NR
+\NC image             \NC 1         \NC image     \NC output an image (the argument can be either an \type
+                                                      {<image>} variable or an \type {image_spec} table)\NC\NR
+\NC comment           \NC any       \NC any       \NC the arguments of this command are ignored\NC\NR
+\stoptabulate
+
+Here is a rather elaborate glyph commands example:
+
+\starttyping
+...
+commands = {
+    { 'push' },                    -- remember where we are
+    { 'right', 5000 },             -- move right about 0.08pt
+    { 'font', 3 },                 -- select the fonts[3] entry
+    { 'char', 97 },                -- place character 97 (ASCII 'a')
+    { 'pop' },                     -- go all the way back
+    { 'down', -200000 },           -- move upwards by about 3pt
+    { 'special', 'pdf: 1 0 0 rg' } -- switch to red color
+    { 'rule', 500000, 20000 }      -- draw a bar
+    { 'special','pdf: 0 g' }       -- back to black
+}
+...
+\stoptyping
+
+The default value for \type {font} is always~1 at the start of the
+\type {commands} array. Therefore, if the virtual font is essentially only a
+re|-|encoding, then you do usually not have create an explicit \quote {font}
+command in the array.
+
+Rules inside of \type {commands} arrays are built up using only two dimensions:
+they do not have depth. For correct vertical placement, an extra \type {down}
+command may be needed.
+
+Regardless of the amount of movement you create within the \type {commands}, the
+output pointer will always move by exactly the width that was given in the \type
+{width} key of the character hash. Any movements that take place inside the \type
+{commands} array are ignored on the upper level.
+
+\subsection{Artificial fonts}
+
+Even in a \quote {real} font, there can be virtual characters. When \LUATEX\
+encounters a \type {commands} field inside a character when it becomes time to
+typeset the character, it will interpret the commands, just like for a true
+virtual character. In this case, if you have created no \quote {fonts} array,
+then the default (and only) \quote {base} font is taken to be the current font
+itself. In practice, this means that you can create virtual duplicates of
+existing characters which is useful if you want to create composite characters.
+
+Note: this feature does {\it not\/} work the other way around. There can not be
+\quote {real} characters in a virtual font! You cannot use this technique for
+font re-encoding either; you need a truly virtual font for that (because
+characters that are already present cannot be altered).
+
+\subsection{Example virtual font}
+
+Finally, here is a plain \TEX\ input file with a virtual font demonstration:
+
+\startbuffer
+\directlua {
+  callback.register('define_font',
+    function (name,size)
+      if name == 'cmr10-red' then
+        f = font.read_tfm('cmr10',size)
+        f.name = 'cmr10-red'
+        f.type = 'virtual'
+        f.fonts = {{ name = 'cmr10', size = size }}
+        for i,v in pairs(f.characters) do
+          if (string.char(i)):find('[tacohanshartmut]') then
+             v.commands = {
+               {'special','pdf: 1 0 0 rg'},
+               {'char',i},
+               {'special','pdf: 0 g'},
+              }
+          else
+             v.commands = {{'char',i}}
+          end
+        end
+      else
+        f = font.read_tfm(name,size)
+      end
+      return f
+    end
+  )
+}
+
+\font\myfont = cmr10-red at 10pt \myfont  This is a line of text \par
+\font\myfontx= cmr10 at 10pt \myfontx Here is another line of text \par
+\stopbuffer
+
+\typebuffer
+
+% \getbuffer
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-introduction.tex b/doc/context/sources/general/manuals/luatex/luatex-introduction.tex
new file mode 100644
index 000000000..23b921129
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-introduction.tex
@@ -0,0 +1,86 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-introduction
+
+\startchapter[title=Introduction]
+
+This book will eventually become the reference manual of \LUATEX. At the moment,
+it simply reports the behavior of the executable matching the snapshot or beta
+release date in the title page.
+
+Features may come and go. The current version of \LUATEX\ can be used for
+production (in fact it is used in production by the authors) but users cannot
+depend on complete stability, nor on functionality staying the same. This means
+that when you update your binary, you also need to check if something fundamental
+has changed. Normally this is communicated in articles or messages to a mailing
+list. We're still not at version 1 but when we reach that state the interface
+will be stable. Of course we then can decide to move towards version 2 with
+different properties.
+
+Don't expect \LUATEX\ to behave the same as \PDFTEX ! Although the core
+functionality of that 8 bit engine is present, \LUATEX\ can behave different due
+to not only its 32 bit character: there is native \UTF\ input, support for wide
+fonts, and the math machinery is tuned for \OPENTYPE\ math. Also, the log output
+can differ (and will likely differ more as we move forward).
+
+\LUATEX\ consists of a number of interrelated but (still) distinguishable parts.
+The organization of the source code is adapted so that it cna glue all these
+components together. We continue cleaning up side effects of the accumulated
+code in \TEX\ engines (especially code that is not needed any longer).
+
+\startitemize[packed]
+    \startitem
+        Most of \PDFTEX\ version 1.40.9, converted to C (with patches from later
+        releases). Some experimental features have been removed and some utility
+        macros are not inherited as their functionality can be done in \LUA. We
+        still use the \type {\pdf*} primitive namespace.
+    \stopitem
+    \startitem
+        The direction model and some other bits from \ALEPH\ RC4 (derived from
+        \OMEGA) is included. The related primitives are part of core \LUATEX.
+    \stopitem
+    \startitem
+        We currently use \LUA\ 5.2.*. At some point we might decide to move to
+        5.3.* but that is yet to be decided.
+    \stopitem
+    \startitem
+        There are few \LUA\ libraries that we consider part of the core \LUA\
+        machinery.
+    \stopitem
+    \startitem
+        There are additional \LUA\ libraries that interface to the internals of
+        \TEX.
+    \stopitem
+    \startitem
+        There are various \TEX\ extensions but only those that cannot be done
+        using the \LUA\ interfaces.
+    \stopitem
+    \startitem
+        The fontloader uses parts of \FONTFORGE\ 2008.11.17 combined with
+        additionaL code specific for usage in a \TEX\ engine.
+    \stopitem
+    \startitem
+        the \METAPOST\ library
+    \stopitem
+\stopitemize
+
+Neither \ALEPH's I/O translation processes, nor tcx files, nor \ENCTEX\ can be
+used, these encoding|-|related functions are superseded by a \LUA|-|based
+solution (reader callbacks).
+
+The yearly \TEXLIVE\ version is the stable version, any version between them is
+considered beta. Keep in mind that new (or changed) features also need to be
+reflected in the macro package that you use.
+
+\blank[3*big]
+
+\starttabulate
+\NC \LUATEX   \EQ Version \number\luatexversion.\luatexrevision \NC \NR
+\NC \CONTEXT  \EQ \contextversion \NC \NR
+\NC timestamp \EQ \currentdate \NC \NR
+\stoptabulate
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-languages.tex b/doc/context/sources/general/manuals/luatex/luatex-languages.tex
new file mode 100644
index 000000000..56978b0fd
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-languages.tex
@@ -0,0 +1,514 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-languages
+
+\startchapter[reference=languages,title={Languages and characters, fonts and glyphs}]
+
+\LUATEX's internal handling of the characters and glyphs that eventually become
+typeset is quite different from the way \TEX82 handles those same objects. The
+easiest way to explain the difference is to focus on unrestricted horizontal mode
+(i.e.\ paragraphs) and hyphenation first. Later on, it will be easy to deal
+with the differences that occur in horizontal and math modes.
+
+In \TEX82, the characters you type are converted into \type {char_node} records
+when they are encountered by the main control loop. \TEX\ attaches and processes
+the font information while creating those records, so that the resulting \quote
+{horizontal list} contains the final forms of ligatures and implicit kerning.
+This packaging is needed because we may want to get the effective width of for
+instance a horizontal box.
+
+When it becomes necessary to hyphenate words in a paragraph, \TEX\ converts (one
+word at time) the \type {char_node} records into a string array by replacing
+ligatures with their components and ignoring the kerning. Then it runs the
+hyphenation algorithm on this string, and converts the hyphenated result back
+into a \quote {horizontal list} that is consecutively spliced back into the
+paragraph stream. Keep in mind that the paragraph may contain unboxed horizontal
+material, which then already contains ligatures and kerns and the words therein
+are part of the hyphenation process.
+
+The \type {char_node} records are somewhat misnamed, as they are glyph positions
+in specific fonts, and therefore not really \quote {characters} in the linguistic
+sense. There is no language information inside the \type {char_node} records.
+Instead, language information is passed along using \type {language whatsit}
+records inside the horizontal list.
+
+In \LUATEX, the situation is quite different. The characters you type are always
+converted into \type {glyph_node} records with a special subtype to identify them
+as being intended as linguistic characters. \LUATEX\ stores the needed language
+information in those records, but does not do any font|-|related processing at
+the time of node creation. It only stores the index of the current font.
+
+When it becomes necessary to typeset a paragraph, \LUATEX\ first inserts all
+hyphenation points right into the whole node list. Next, it processes all the
+font information in the whole list (creating ligatures and adjusting kerning),
+and finally it adjusts all the subtype identifiers so that the records are \quote
+{glyph nodes} from now on.
+
+That was the broad overview. The rest of this chapter will deal with the minutiae
+of the new process.
+
+\section[charsandglyphs]{Characters and glyphs}
+
+\TEX82 (including \PDFTEX) differentiates between \type {char_node}s and \type
+{lig_node}s. The former are simple items that contained nothing but a \quote
+{character} and a \quote {font} field, and they lived in the same memory as
+tokens did. The latter also contained a list of components, and a subtype
+indicating whether this ligature was the result of a word boundary, and it was
+stored in the same place as other nodes like boxes and kerns and glues.
+
+In \LUATEX, these two types are merged into one, somewhat larger structure called
+a \type {glyph_node}. Besides having the old character, font, and component
+fields, and the new special fields like \quote {attr}
+(see~\in{section}[glyphnodes]), these nodes also contain:
+
+\startitemize
+
+\startitem A subtype, split into four main types:
+
+    \startitemize
+        \startitem
+            \type {character}, for characters to be hyphenated: the lowest bit
+            (bit 0) is set to 1.
+        \stopitem
+        \startitem
+            \type {glyph}, for specific font glyphs: the lowest bit (bit 0) is
+            not set.
+        \stopitem
+        \startitem
+            \type {ligature}, for ligatures (bit 1 is set)
+        \stopitem
+        \startitem
+            \type {ghost}, for \quote {ghost objects} (bit 2 is set)
+        \stopitem
+    \stopitemize
+
+    The latter two make further use of two extra fields (bits 3 and 4):
+
+    \startitemize
+        \startitem
+            \type {left}, for ligatures created from a left word boundary and for
+            ghosts created from \type {\leftghost}
+        \stopitem
+        \startitem
+            \type {right}, for ligatures created from a right word boundary and
+            for ghosts created from \type {\rightghost}
+        \stopitem
+   \stopitemize
+
+   For ligatures, both bits can be set at the same time (in case of a
+   single|-|glyph word).
+
+\stopitem
+
+\startitem
+    \type {glyph_node}s of type \quote {character} also contain language data,
+    split into four items that were current when the node was created: the
+    \type {\setlanguage} (15 bits), \type {\lefthyphenmin} (8 bits), \type
+    {\righthyphenmin} (8 bits), and \type {\uchyph} (1 bit).
+\stopitem
+
+\stopitemize
+
+Incidentally, \LUATEX\ allows 16383 separate languages, and words can be 256
+characters long.
+
+The new primitive \type {\hyphenationmin} can be used to signal the minimal length
+of a word. This value stored with the (current) language.
+
+Because the \type {\uchyph} value is saved in the actual nodes, its handling is
+subtly different from \TEX82: changes to \type {\uchyph} become effective
+immediately, not at the end of the current partial paragraph.
+
+Typeset boxes now always have their language information embedded in the nodes
+themselves, so there is no longer a possible dependency on the surrounding
+language settings. In \TEX82, a mid-paragraph statement like \type {\unhbox0} would
+process the box using the current paragraph language unless there was a
+\type {\setlanguage} issued inside the box. In \LUATEX, all language variables are
+already frozen.
+
+\section{The main control loop}
+
+In \LUATEX's main loop, almost all input characters that are to be typeset are
+converted into \type {glyph} node records with subtype \quote {character}, but
+there are a few exceptions.
+
+First, the \type {\accent} primitives creates nodes with subtype \quote {glyph}
+instead of \quote {character}: one for the actual accent and one for the
+accentee. The primary reason for this is that \type {\accent} in \TEX82 is
+explicitly dependent on the current font encoding, so it would not make much
+sense to attach a new meaning to the primitive's name, as that would invalidate
+many old documents and macro packages. A secondary reason is that in \TEX82,
+\type {\accent} prohibits hyphenation of the current word. Since in \LUATEX\
+hyphenation only takes place on \quote {character} nodes, it is possible to
+achieve the same effect.
+
+This change of meaning did happen with \type {\char}, that now generates \quote
+{glyph} nodes with a character subtype. In traditional \TEX\ there was a strong
+relationship betwene the 8|-|bit input encoding, hyphenation and glyph staken
+from a font. In \LUATEX\ we have \UTF\ input, and in most cases this maps
+directly to a character in a font, apart from glyph replacement in the font
+engine. If you want to access arbitrary glyphs in a font directly you can alwasy
+use \LUA\ to do so, because fonts are available as \LUA\ table.
+
+Second, all the results of processing in math mode eventually become nodes with
+\quote {glyph} subtypes.
+
+Third, the \ALEPH|-|derived commands \type {\leftghost} and \type {\rightghost}
+create nodes of a third subtype: \quote {ghost}. These nodes are ignored
+completely by all further processing until the stage where inter|-|glyph kerning
+is added.
+
+Fourth, automatic discretionaries are handled differently. \TEX82 inserts an
+empty discretionary after sensing an input character that matches the \type
+{\hyphenchar} in the current font. This test is wrong, in our opinion: whether or
+not hyphenation takes place should not depend on the current font, it is a
+language property.
+
+In \LUATEX, it works like this: if \LUATEX\ senses a string of input characters
+that matches the value of the new integer parameter \type {\exhyphenchar}, it will
+insert an explicit discretionary after that series of nodes. Initex sets the \type
+{\exhyphenchar=`\-}. Incidentally, this is a global parameter instead of a
+language-specific one because it may be useful to change the value depending on
+the document structure instead of the text language.
+
+The insertion of discretionaries after a sequence of explicit hyphens happens at
+the same time as the other hyphenation processing, {\it not\/} inside the main
+control loop.
+
+The only use \LUATEX\ has for \type {\hyphenchar} is at the check whether a word
+should be considered for hyphenation at all. If the \type {\hyphenchar} of the font
+attached to the first character node in a word is negative, then hyphenation of
+that word is abandoned immediately. {\bf This behavior is added for backward
+compatibility only, and the use of \type {\hyphenchar=-1} as a means of
+preventing hyphenation should not be used in new \LUATEX\ documents.}
+
+Fifth, \type {\setlanguage} no longer creates whatsits. The meaning of \type
+{\setlanguage} is changed so that it is now an integer parameter like all others.
+That integer parameter is used in \type {\glyph_node} creation to add language
+information to the glyph nodes. In conjunction, the \type {\language} primitive is
+extended so that it always also updates the value of \type {\setlanguage}.
+
+Sixth, the \type {\noboundary} command (this command prohibits word boundary
+processing where that would normally take place) now does create whatsits. These
+whatsits are needed because the exact place of the \type {\noboundary} command in
+the input stream has to be retained until after the ligature and font processing
+stages.
+
+Finally, there is no longer a \type {main_loop} label in the code. Remember that
+\TEX82 did quite a lot of processing while adding \type {char_nodes} to the
+horizontal list? For speed reasons, it handled that processing code outside of
+the \quote {main control} loop, and only the first character of any \quote {word}
+was handled by that \quote {main control} loop. In \LUATEX, there is no longer a
+need for that (all hard work is done later), and the (now very small) bits of
+character|-|handling code have been moved back inline. When \type
+{\tracingcommands} is on, this is visible because the full word is reported,
+instead of just the initial character.
+
+\section[patternsexceptions]{Loading patterns and exceptions}
+
+The hyphenation algorithm in \LUATEX\ is quite different from the one in \TEX82,
+although it uses essentially the same user input.
+
+After expansion, the argument for \type {\patterns} has to be proper \UTF8 with
+individual patterns separated by spaces, no \type {\char} or \type {\chardef}d
+commands are allowed. The current implementation is even more strict, and will
+reject all non|-|\UNICODE\ characters, but that will be changed in the future.
+For now, the generated errors are a valuable tool in discovering font-encoding
+specific pattern files.
+
+Likewise, the expanded argument for \type {\hyphenation} also has to be proper
+\UTF8, but here a tiny little bit of extra syntax is provided:
+
+\startitemize[n]
+\startitem
+    Three sets of arguments in curly braces (\type {{}{}{}}) indicates a desired
+    complex discretionary, with arguments as in \type {\discretionary}'s command in
+    normal document input.
+\stopitem
+\startitem
+    A \type {-} indicates a desired simple discretionary, cf.\ \type {\-} and \type
+    {\discretionary{-}{}{}} in normal document input.
+\stopitem
+\startitem
+    Internal command names are ignored. This rule is provided especially for \type
+    {\discretionary}, but it also helps to deal with \type {\relax} commands that
+    may sneak in.
+\stopitem
+\startitem
+    An \type {=} indicates a (non|-|discretionary) hyphen in the document input.
+\stopitem
+\stopitemize
+
+The expanded argument is first converted back to a space-separated string while
+dropping the internal command names. This string is then converted into a
+dictionary by a routine that creates key|-|value pairs by converting the other
+listed items. It is important to note that the keys in an exception dictionary
+can always be generated from the values. Here are a few examples:
+
+\starttabulate[|l|l|l|]
+\NC \ssbf value \NC \ssbf implied key (input) \NC \ssbf effect \NC\NR
+\NC \type {ta-ble} \NC table \NC \type {ta\-ble} ($=$ \type {ta\discretionary{-}{}{}ble}) \NC\NR
+\NC \type {ba{k-}{}{c}ken} \NC backen \NC \type {ba\discretionary{k-}{}{c}ken} \NC\NR
+\stoptabulate
+
+The resultant patterns and exception dictionary will be stored under the language
+code that is the present value of \type {\language}.
+
+In the last line of the table, you see there is no \type {\discretionary} command
+in the value: the command is optional in the \TEX-based input syntax. The
+underlying reason for that is that it is conceivable that a whole dictionary of
+words is stored as a plain text file and loaded into \LUATEX\ using one of the
+functions in the \LUA\ \type {lang} library. This loading method is quite a bit
+faster than going through the \TEX\ language primitives, but some (most?) of that
+speed gain would be lost if it had to interpret command sequences while doing so.
+
+It is possible to specify extra hyphenation points in compound words by using
+\type {{-}{}{-}} for the explicit hyphen character (replace \type {-} by the
+actual explicit hyphen character if needed). For example, this matches the word
+\quote {multi|-|word|-|boundaries} and allows an extra break inbetweem \quote
+{boun} and \quote {daries}:
+
+\starttyping
+\hyphenation{multi{-}{}{-}word{-}{}{-}boun-daries}
+\stoptyping
+
+The motivation behind the \ETEX\ extension \type {\savinghyphcodes} was that
+hyphenation heavily depended on font encodings. This is no longer true in
+\LUATEX, and the corresponding primitive is ignored pending complete removal. The
+future semantics of \type {\uppercase} and \type {\lowercase} are still under
+consideration, no changes have taken place yet.
+
+\section{Applying hyphenation}
+
+The internal structures \LUATEX\ uses for the insertion of discretionaries in
+words is very different from the ones in \TEX82, and that means there are some
+noticeable differences in handling as well.
+
+First and foremost, there is no \quote {compressed trie} involved in hyphenation.
+The algorithm still reads \PATGEN-generated pattern files, but \LUATEX\ uses a
+finite state hash to match the patterns against the word to be hyphenated. This
+algorithm is based on the \quote {libhnj} library used by \OPENOFFICE, which in
+turn is inspired by \TEX. The memory allocation for this new implementation is
+completely dynamic, so the \WEBC\ setting for \type {trie_size} is ignored.
+
+Differences between \LUATEX\ and \TEX82 that are a direct result of that:
+
+\startitemize
+\startitem
+    \LUATEX\ happily hyphenates the full \UNICODE\ character range.
+\stopitem
+\startitem
+    Pattern and exception dictionary size is limited by the available memory
+    only, all allocations are done dynamically. The trie|-|related settings in
+    \type {texmf.cnf} are ignored.
+\stopitem
+\startitem
+    Because there is no \quote {trie preparation} stage, language patterns never
+    become frozen. This means that the primitive \type {\patterns} (and its \LUA\
+    counterpart \type {lang.patterns}) can be used at any time, not only in
+    ini\TEX.
+\stopitem
+\startitem
+    Only the string representation of \type {\patterns} and \type {\hyphenation} is
+    stored in the format file. At format load time, they are simply
+    re|-|evaluated. It follows that there is no real reason to preload languages
+    in the format file. In fact, it is usually not a good idea to do so. It is
+    much smarter to load patterns no sooner than the first time they are actually
+    needed.
+\stopitem
+\startitem
+    \LUATEX\ uses the language-specific variables \type {\prehyphenchar} and \type
+    {\posthyphenchar} in the creation of implicit discretionaries, instead of
+    \TEX82's \type {\hyphenchar}, and the values of the language|-|specific variables
+    \type {\preexhyphenchar} and \type {\postexhyphenchar} for explicit
+    discretionaries (instead of \TEX82's empty discretionary).
+\stopitem
+\startitem
+    The value of the two counters related to hyphenation, \type {hyphenpenalty}
+    and \type {exhyphenpenalty}, are now stored in the discretionary nodes. This
+    permits a local overload for explicit \type {\discretionary} commands. The
+    value current when the hyphenation pass is applied is used. When no callbacks
+    are used this is compatible with traditional \TEX. When you apply the \LUA\
+    \type {lang.hyphenate} function the current values are used.
+\stopitem
+\stopitemize
+
+Inserted characters and ligatures inherit their attributes from the nearest glyph
+node item (usually the preceding one, but the following one for the items
+inserted at the left-hand side of a word).
+
+Word boundaries are no longer implied by font switches, but by language switches.
+One word can have two separate fonts and still be hyphenated correctly (but it
+can not have two different languages, the \type {\setlanguage} command forces a
+word boundary).
+
+All languages start out with \type {\prehyphenchar=`\-}, \type {\posthyphenchar=0},
+\type {\preexhyphenchar=0} and \type {\postexhyphenchar=0}. When you assign the
+values of one of these four parameters, you are actually changing the settings
+for the current \type {\language}, this behavior is compatible with \type {\patterns}
+and \type {\hyphenation}.
+
+\LUATEX\ also hyphenates the first word in a paragraph. Words can be up to 256
+characters long (up from 64 in \TEX82). Longer words generate an error right now,
+but eventually either the limitation will be removed or perhaps it will become
+possible to silently ignore the excess characters (this is what happens in
+\TEX82, but there the behavior cannot be controlled).
+
+If you are using the \LUA\ function \type {lang.hyphenate}, you should be aware
+that this function expects to receive a list of \quote {character} nodes. It will
+not operate properly in the presence of \quote {glyph}, \quote {ligature}, or
+\quote {ghost} nodes, nor does it know how to deal with kerning. In the near
+future, it will be able to skip over \quote {ghost} nodes, and we may add a less
+fuzzy function you can call as well.
+
+The hyphenation exception dictionary is maintained as key|-|value hash, and that
+is also dynamic, so the \type {hyph_size} setting is not used either.
+
+\section{Applying ligatures and kerning}
+
+After all possible hyphenation points have been inserted in the list, \LUATEX\
+will process the list to convert the \quote {character} nodes into \quote {glyph}
+and \quote {ligature} nodes. This is actually done in two stages: first all
+ligatures are processed, then all kerning information is applied to the result
+list. But those two stages are somewhat dependent on each other: If the used font
+makes it possible to do so, the ligaturing stage adds virtual \quote {character}
+nodes to the word boundaries in the list. While doing so, it removes and
+interprets \type {noboundary} nodes. The kerning stage deletes those word
+boundary items after it is done with them, and it does the same for \quote
+{ghost} nodes. Finally, at the end of the kerning stage, all remaining \quote
+{character} nodes are converted to \quote {glyph} nodes.
+
+This work separation is worth mentioning because, if you overrule from \LUA\ only
+one of the two callbacks related to font handling, then you have to make sure you
+perform the tasks normally done by \LUATEX\ itself in order to make sure that the
+other, non|-|overruled, routine continues to function properly.
+
+Work in this area is not yet complete, but most of the possible cases are handled
+by our rewritten ligaturing engine. We are working hard to make sure all of the
+possible inputs will become supported soon.
+
+For example, take the word \type {office}, hyphenated \type {of-fice}, using a
+\quote {normal} font with all the \type {f}-\type {f} and \type {f}-\type {i}
+type ligatures:
+
+\starttabulate[|l|l|]
+\NC Initial:               \NC \type {{o}{f}{f}{i}{c}{e}}             \NC\NR
+\NC After hyphenation:     \NC \type {{o}{f}{{-},{},{}}{f}{i}{c}{e}}  \NC\NR
+\NC First ligature stage:  \NC \type {{o}{{f-},{f},{<ff>}}{i}{c}{e}}  \NC\NR
+\NC Final result:          \NC \type {{o}{{f-},{<fi>},{<ffi>}}{c}{e}} \NC\NR
+\stoptabulate
+
+That's bad enough, but let us assume that there is also a hyphenation point
+between the \type {f} and the \type {i}, to create \type {of-f-ice}. Then the
+final result should be:
+
+\starttyping
+{o}{{f-},
+    {{f-},
+     {i},
+     {<fi>}},
+    {{<ff>-},
+     {i},
+     {<ffi>}}}{c}{e}
+\stoptyping
+
+with discretionaries in the post-break text as well as in the replacement text of
+the top-level discretionary that resulted from the first hyphenation point.
+
+Here is that nested solution again, in a different representation:
+
+\starttabulate[|l|l|l|l|]
+\NC         \NC pre              \NC post          \NC replace           \NC \NR
+\NC topdisc \NC \type {f-}$^1$   \NC sub1          \NC sub2              \NC \NR
+\NC sub1    \NC \type {f-}$^2$   \NC \type {i}$^3$ \NC \type {<fi>}$^4$  \NC \NR
+\NC sub2    \NC \type {<ff>-}$^5$\NC \type {i}$^6$ \NC \type {<ffi>}$^7$ \NC \NR
+\stoptabulate
+
+When line breaking is choosing its breakpoints, the following fields will
+eventually be selected:
+
+\starttabulate[|l|l|l|]
+\NC \type {of-f-ice} \NC \type {f-}$^1$    \NC \NR
+\NC                  \NC \type {f-}$^2$    \NC \NR
+\NC                  \NC \type {i}$^3$     \NC \NR
+\NC \type {of-fice}  \NC \type {f-}$^1$    \NC \NR
+\NC                  \NC \type {<fi>}$^4$  \NC \NR
+\NC \type {off-ice}  \NC \type {<ff>-}$^5$ \NC \NR
+\NC                  \NC \type {i}$^6$     \NC \NR
+\NC \type {office}   \NC \type {<ffi>}$^7$ \NC \NR
+\stoptabulate
+
+The current solution in \LUATEX\ is not able to handle nested discretionaries,
+but it is in fact smart enough to handle this fictional \type {of-f-ice} example.
+It does so by combining two sequential discretionary nodes as if they were a
+single object (where the second discretionary node is treated as an extension of
+the first node).
+
+One can observe that the \type {of-f-ice} and \type {off-ice} cases both end with
+the same actual post replacement list (\type {i}), and that this would be the
+case even if that \type {i} was the first item of a potential following ligature
+like \type {ic}. This allows \LUATEX\ to do away with one of the fields, and thus
+make the whole stuff fit into just two discretionary nodes.
+
+The mapping of the seven list fields to the six fields in this discretionary node
+pair is as follows:
+
+\starttabulate[|l|p|]
+\NC \bf field            \NC \bf description \NC \NR
+\NC \type {disc1.pre}     \NC \type {f-}$^1$  \NC \NR
+\NC \type {disc1.post}    \NC \type {<fi>}$^4$  \NC \NR
+\NC \type {disc1.replace} \NC \type {<ffi>}$^7$ \NC \NR
+\NC \type {disc2.pre}     \NC \type {f-}$^2$  \NC \NR
+\NC \type {disc2.post}    \NC \type {i}$^{3{,}6}$\NC \NR
+\NC \type {disc2.replace} \NC \type {<ff>-}$^5$\NC \NR
+\stoptabulate
+
+What is actually generated after ligaturing has been applied is therefore:
+
+\starttyping
+{o}{{f-},
+    {<fi>},
+    {<ffi>}}
+   {{f-},
+    {i},
+    {<ff>-}}{c}{e}
+\stoptyping
+
+The two discretionaries have different subtypes from a discretionary appearing on
+its own: the first has subtype 4, and the second has subtype 5. The need for
+these special subtypes stems from the fact that not all of the fields appear in
+their \quote {normal} location. The second discretionary especially looks odd,
+with things like the \type {<ff>-} appearing in \type {disc2.replace}. The fact
+that some of the fields have different meanings (and different processing code
+internally) is what makes it necessary to have different subtypes: this enables
+\LUATEX\ to distinguish this sequence of two joined discretionary nodes from the
+case of two standalone discretionaries appearing in a row.
+
+Of course there is still that relationship with fonts: ligatures can be implemented by
+mapping a sequence of glyphs onto one glyph, but also by selective replacement and
+kerning. This means that the above examples are just representing the traditional
+approach.
+
+\section{Breaking paragraphs into lines}
+
+This code is still almost unchanged, but because of the above|-|mentioned changes
+with respect to discretionaries and ligatures, line breaking will potentially be
+different from traditional \TEX. The actual line breaking code is still based on
+the \TEX82 algorithms, and it does not expect there to be discretionaries inside
+of discretionaries.
+
+But that situation is now fairly common in \LUATEX, due to the changes to the
+ligaturing mechanism. And also, the \LUATEX\ discretionary nodes are implemented
+slightly different from the \TEX82 nodes: the \type {no_break} text is now
+embedded inside the disc node, where previously these nodes kept their place in
+the horizontal list (the discretionary node contained a counter indicating how
+many nodes to skip).
+
+The combined effect of these two differences is that \LUATEX\ does not always use
+all of the potential breakpoints in a paragraph, especially when fonts with many
+ligatures are used.
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-libraries.tex b/doc/context/sources/general/manuals/luatex/luatex-libraries.tex
new file mode 100644
index 000000000..df03e348d
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-libraries.tex
@@ -0,0 +1,6199 @@
+\environment luatex-style
+\environment luatex-logos
+
+% HH: to be checked
+
+\startcomponent luatex-libraries
+
+\startchapter[reference=libraries,title={\LUATEX\ \LUA\ Libraries}]
+
+The implied use of the built|-|in \LUA\ modules \type {epdf}, \type {fontloader},
+\type {mplib}, and \type {pdfscanner} is deprecated. If you want to use these,
+please start your source file with a proper \type {require} line. In the future,
+\LUATEX\ will switch to loading these modules on demand.
+
+The interfacing between \TEX\ and \LUA\ is facilitated by a set of library
+modules. The \LUA\ libraries in this chapter are all defined and initialized by
+the \LUATEX\ executable. Together, they allow \LUA\ scripts to query and change a
+number of \TEX's internal variables, run various internal \TEX\ functions, and
+set up \LUATEX's hooks to execute \LUA\ code.
+
+The following sections are in alphabetical order.
+
+\section{The \type {callback} library}
+
+This library has functions that register, find and list callbacks. Callbacks are
+\LUA\ functions that are called in well defined places. There are two kind of
+callbacks: those that mix with existing functionality, and those that (when
+enabled) replace functionality. In mosty cases the second category is expected to
+behave similar to the built in functiontionality because in a next step specific
+data is expected. For instance, you can replace the hyphenation routine. The
+function gets a list that can be hyphenated (or not). The final list should be
+valid and is (normally) used for constructing a paragraph. Another function can
+replace the ligature builder and|/|or kerner. Doing something else is possible
+but in the end might not give the user the expected outcome.
+
+The first thing you need to do is registering a callback:
+
+\startfunctioncall
+id, error = callback.register (<string> callback_name, <function> func)
+id, error = callback.register (<string> callback_name, nil)
+id, error = callback.register (<string> callback_name, false)
+\stopfunctioncall
+
+Here the \syntax {callback_name} is a predefined callback name, see below. The
+function returns the internal \type {id} of the callback or \type {nil}, if the
+callback could not be registered. In the latter case, \type {error} contains an
+error message, otherwise it is \type {nil}.
+
+\LUATEX\ internalizes the callback function in such a way that it does not matter
+if you redefine a function accidentally.
+
+Callback assignments are always global. You can use the special value \type {nil}
+instead of a function for clearing the callback.
+
+For some minor speed gain, you can assign the boolean \type {false} to the
+non|-|file related callbacks, doing so will prevent \LUATEX\ from executing
+whatever it would execute by default (when no callback function is registered at
+all). Be warned: this may cause all sorts of grief unless you know {\em exactly}
+what you are doing!
+
+Currently, callbacks are not dumped into the format file.
+
+\startfunctioncall
+<table> info = callback.list()
+\stopfunctioncall
+
+The keys in the table are the known callback names, the value is a boolean where
+\type {true} means that the callback is currently set (active).
+
+\startfunctioncall
+<function> f = callback.find (callback_name)
+\stopfunctioncall
+
+If the callback is not set, \type {callback.find} returns \type {nil}.
+
+\subsection{File discovery callbacks}
+
+The behavior documented in this subsection is considered stable in the sense that
+there will not be backward|-|incompatible changes any more.
+
+\subsubsection{\type {find_read_file} and \type {find_write_file}}
+
+Your callback function should have the following conventions:
+
+\startfunctioncall
+<string> actual_name = function (<number> id_number, <string> asked_name)
+\stopfunctioncall
+
+Arguments:
+
+\startitemize
+
+\sym{id_number}
+
+This number is zero for the log or \type {\input} files. For \TEX's \type {\read}
+or \type {\write} the number is incremented by one, so \type {\read0} becomes~1.
+
+\sym{asked_name}
+
+This is the user|-|supplied filename, as found by \type {\input}, \type {\openin}
+or \type {\openout}.
+
+\stopitemize
+
+Return value:
+
+\startitemize
+
+\sym{actual_name}
+
+This is the filename used. For the very first file that is read in by \TEX, you
+have to make sure you return an \type {actual_name} that has an extension and
+that is suitable for use as \type {jobname}. If you don't, you will have to
+manually fix the name of the log file and output file after \LUATEX\ is finished,
+and an eventual format filename will become mangled. That is because these file
+names depend on the jobname.
+
+You have to return \type {nil} if the file cannot be found.
+
+\stopitemize
+
+\subsubsection{\type {find_font_file}}
+
+Your callback function should have the following conventions:
+
+\startfunctioncall
+<string> actual_name = function (<string> asked_name)
+\stopfunctioncall
+
+The \type {asked_name} is an \OTF\ or \TFM\ font metrics file.
+
+Return \type {nil} if the file cannot be found.
+
+\subsubsection{\type {find_output_file}}
+
+Your callback function should have the following conventions:
+
+\startfunctioncall
+<string> actual_name = function (<string> asked_name)
+\stopfunctioncall
+
+The \type {asked_name} is the \PDF\ or \DVI\ file for writing.
+
+\subsubsection{\type {find_format_file}}
+
+Your callback function should have the following conventions:
+
+\startfunctioncall
+<string> actual_name = function (<string> asked_name)
+\stopfunctioncall
+
+The \type {asked_name} is a format file for reading (the format file for writing
+is always opened in the current directory).
+
+\subsubsection{\type {find_vf_file}}
+
+Like \type {find_font_file}, but for virtual fonts. This applies to both \ALEPH's
+\OVF\ files and traditional Knuthian \VF\ files.
+
+\subsubsection{\type {find_map_file}}
+
+Like \type {find_font_file}, but for map files.
+
+\subsubsection{\type {find_enc_file}}
+
+Like \type {find_font_file}, but for enc files.
+
+\subsubsection{\type {find_sfd_file}}
+
+Like \type {find_font_file}, but for subfont definition files.
+
+\subsubsection{\type {find_pk_file}}
+
+Like \type {find_font_file}, but for pk bitmap files. The argument \type
+{asked_name} is a bit special in this case. Its form is
+
+\starttyping
+<base res>dpi/<fontname>.<actual res>pk
+\stoptyping
+
+So you may be asked for \type {600dpi/manfnt.720pk}. It is up to you to find a
+\quote {reasonable} bitmap file to go with that specification.
+
+\subsubsection{\type {find_data_file}}
+
+Like \type {find_font_file}, but for embedded files (\type {\pdfobj file '...'}).
+
+\subsubsection{\type {find_opentype_file}}
+
+Like \type {find_font_file}, but for \OPENTYPE\ font files.
+
+\subsubsection{\type {find_truetype_file} and \type {find_type1_file}}
+
+Your callback function should have the following conventions:
+
+\startfunctioncall
+<string> actual_name = function (<string> asked_name)
+\stopfunctioncall
+
+The \type {asked_name} is a font file. This callback is called while \LUATEX\ is
+building its internal list of needed font files, so the actual timing may
+surprise you. Your return value is later fed back into the matching \type
+{read_file} callback.
+
+Strangely enough, \type {find_type1_file} is also used for \OPENTYPE\ (\OTF)
+fonts.
+
+\subsubsection{\type {find_image_file}}
+
+Your callback function should have the following conventions:
+
+\startfunctioncall
+<string> actual_name = function (<string> asked_name)
+\stopfunctioncall
+
+The \type {asked_name} is an image file. Your return value is used to open a file
+from the harddisk, so make sure you return something that is considered the name
+of a valid file by your operating system.
+
+\subsection[iocallback]{File reading callbacks}
+
+The behavior documented in this subsection is considered stable in the sense that
+there will not be backward-incompatible changes any more.
+
+\subsubsection{\type {open_read_file}}
+
+Your callback function should have the following conventions:
+
+\startfunctioncall
+<table> env = function (<string> file_name)
+\stopfunctioncall
+
+Argument:
+
+\startitemize
+
+\sym{file_name}
+
+The filename returned by a previous \type {find_read_file} or the return value of
+\type {kpse.find_file()} if there was no such callback defined.
+
+\stopitemize
+
+Return value:
+
+\startitemize
+
+\sym{env}
+
+This is a table containing at least one required and one optional callback
+function for this file. The required field is \type {reader} and the associated
+function will be called once for each new line to be read, the optional one is
+\type {close} that will be called once when \LUATEX\ is done with the file.
+
+\LUATEX\ never looks at the rest of the table, so you can use it to store your
+private per|-|file data. Both the callback functions will receive the table as
+their only argument.
+
+\stopitemize
+
+\subsubsubsection{\type {reader}}
+
+\LUATEX\ will run this function whenever it needs a new input line from the file.
+
+\startfunctioncall
+function(<table> env)
+    return <string> line
+end
+\stopfunctioncall
+
+Your function should return either a string or \type {nil}. The value \type {nil}
+signals that the end of file has occurred, and will make \TEX\ call the optional
+\type {close} function next.
+
+\subsubsubsection{\type {close}}
+
+\LUATEX\ will run this optional function when it decides to close the file.
+
+\startfunctioncall
+function(<table> env)
+end
+\stopfunctioncall
+
+Your function should not return any value.
+
+\subsubsection{General file readers}
+
+There is a set of callbacks for the loading of binary data files. These all use
+the same interface:
+
+\startfunctioncall
+function(<string> name)
+    return <boolean> success, <string> data, <number> data_size
+end
+\stopfunctioncall
+
+The \type {name} will normally be a full path name as it is returned by either
+one of the file discovery callbacks or the internal version of \type
+{kpse.find_file()}.
+
+\startitemize
+
+\sym{success}
+
+Return \type {false} when a fatal error occurred (e.g.\ when the file cannot be
+found, after all).
+
+\sym{data}
+
+The bytes comprising the file.
+
+\sym{data_size}
+
+The length of the \type {data}, in bytes.
+
+\stopitemize
+
+Return an empty string and zero if the file was found but there was a
+reading problem.
+
+The list of functions is as follows:
+
+\starttabulate[|l|p|]
+\NC \type {read_font_file}     \NC ofm or tfm files \NC \NR
+\NC \type {read_vf_file}       \NC virtual fonts \NC \NR
+\NC \type {read_map_file}      \NC map files \NC \NR
+\NC \type {read_enc_file}      \NC encoding files \NC \NR
+\NC \type {read_sfd_file}      \NC subfont definition files \NC \NR
+\NC \type {read_pk_file}       \NC pk bitmap files \NC \NR
+\NC \type {read_data_file}     \NC embedded files (\type {\pdfobj file ...}) \NC \NR
+\NC \type {read_truetype_file} \NC \TRUETYPE\ font files \NC \NR
+\NC \type {read_type1_file}    \NC \TYPEONE\ font files \NC \NR
+\NC \type {read_opentype_file} \NC \OPENTYPE\ font files \NC \NR
+\stoptabulate
+
+\subsection{Data processing callbacks}
+
+\subsubsection{\type {process_input_buffer}}
+
+This callback allows you to change the contents of the line input buffer just
+before \LUATEX\ actually starts looking at it.
+
+\startfunctioncall
+function(<string> buffer)
+    return <string> adjusted_buffer
+end
+\stopfunctioncall
+
+If you return \type {nil}, \LUATEX\ will pretend like your callback never
+happened. You can gain a small amount of processing time from that.
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {process_output_buffer}}
+
+This callback allows you to change the contents of the line output buffer just
+before \LUATEX\ actually starts writing it to a file as the result of a \type
+{\write} command. It is only called for output to an actual file (that is,
+excluding the log, the terminal, and \type {\write18} calls).
+
+\startfunctioncall
+function(<string> buffer)
+    return <string> adjusted_buffer
+end
+\stopfunctioncall
+
+If you return \type {nil}, \LUATEX\ will pretend like your callback never
+happened. You can gain a small amount of processing time from that.
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {process_jobname}}
+
+This callback allows you to change the jobname given by \type {\jobname} in \TEX\
+and \type {tex.jobname} in Lua. It does not affect the internal job name or the
+name of the output or log files.
+
+\startfunctioncall
+function(<string> jobname)
+    return <string> adjusted_jobname
+end
+\stopfunctioncall
+
+The only argument is the actual job name; you should not use \type {tex.jobname}
+inside this function or infinite recursion may occur. If you return \type {nil},
+\LUATEX\ will pretend your callback never happened.
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {token_filter}}
+
+This callback allows you to replace the way \LUATEX\ fetches lexical tokens.
+
+\startfunctioncall
+function()
+    return <table> token
+end
+\stopfunctioncall
+
+The calling convention for this callback is a bit more complicated than for most
+other callbacks. The function should either return a \LUA\ table representing a
+valid to|-|be|-|processed token or tokenlist, or something else like \type {nil}
+or an empty table.
+
+If your \LUA\ function does not return a table representing a valid token, it
+will be immediately called again, until it eventually does return a useful token
+or tokenlist (or until you reset the callback value to nil). See the description
+of \type {token} for some handy functions to be used in conjunction with this
+callback.
+
+If your function returns a single usable token, then that token will be processed
+by \LUATEX\ immediately. If the function returns a token list (a table consisting
+of a list of consecutive token tables), then that list will be pushed to the
+input stack at a completely new token list level, with its token type set to
+\quote {inserted}. In either case, the returned token(s) will not be fed back
+into the callback function.
+
+Setting this callback to \type {false} has no effect (because otherwise nothing
+would happen, forever).
+
+\subsection{Node list processing callbacks}
+
+The description of nodes and node lists is in~\in{chapter}[nodes].
+
+\subsubsection{\type {buildpage_filter}}
+
+This callback is called whenever \LUATEX\ is ready to move stuff to the main
+vertical list. You can use this callback to do specialized manipulation of the
+page building stage like imposition or column balancing.
+
+\startfunctioncall
+function(<string> extrainfo)
+end
+\stopfunctioncall
+
+The string \type {extrainfo} gives some additional information about what \TEX's
+state is with respect to the \quote {current page}. The possible values are:
+
+\starttabulate[|lT|p|]
+\NC \ssbf value     \NC \bf explanation                           \NC \NR
+\NC alignment       \NC a (partial) alignment is being added      \NC \NR
+\NC after_output    \NC an output routine has just finished       \NC \NR
+\NC box             \NC a typeset box is being added              \NC \NR
+%NC pre_box         \NC interline material is being added         \NC \NR
+%NC adjust          \NC \type {\vadjust} material is being added  \NC \NR
+\NC new_graf        \NC the beginning of a new paragraph          \NC \NR
+\NC vmode_par       \NC \type {\par} was found in vertical mode   \NC \NR
+\NC hmode_par       \NC \type {\par} was found in horizontal mode \NC \NR
+\NC insert          \NC an insert is added                        \NC \NR
+\NC penalty         \NC a penalty (in vertical mode)              \NC \NR
+\NC before_display  \NC immediately before a display starts       \NC \NR
+\NC after_display   \NC a display is finished                     \NC \NR
+\NC end             \NC \LUATEX\ is terminating (it's all over)   \NC \NR
+\stoptabulate
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {pre_linebreak_filter}}
+
+This callback is called just before \LUATEX\ starts converting a list of nodes
+into a stack of \type {\hbox}es, after the addition of \type {\parfillskip}.
+
+\startfunctioncall
+function(<node> head, <string> groupcode)
+    return true | false | <node> newhead
+end
+\stopfunctioncall
+
+The string called \type {groupcode} identifies the nodelist's context within
+\TEX's processing. The range of possibilities is given in the table below, but
+not all of those can actually appear in \type {pre_linebreak_filter}, some are
+for the \type {hpack_filter} and \type {vpack_filter} callbacks that will be
+explained in the next two paragraphs.
+
+\starttabulate[|lT|p|]
+\NC \ssbf value   \NC \bf explanation                                 \NC \NR
+\NC <empty>       \NC main vertical list                              \NC \NR
+\NC hbox          \NC \type {\hbox} in horizontal mode                \NC \NR
+\NC adjusted_hbox \NC \type {\hbox} in vertical mode                  \NC \NR
+\NC vbox          \NC \type {\vbox}                                   \NC \NR
+\NC vtop          \NC \type {\vtop}                                   \NC \NR
+\NC align         \NC \type {\halign} or \type {\valign}              \NC \NR
+\NC disc          \NC discretionaries                                 \NC \NR
+\NC insert        \NC packaging an insert                             \NC \NR
+\NC vcenter       \NC \type {\vcenter}                                \NC \NR
+\NC local_box     \NC \type {\localleftbox} or \type {\localrightbox} \NC \NR
+\NC split_off     \NC top of a \type {\vsplit}                        \NC \NR
+\NC split_keep    \NC remainder of a \type {\vsplit}                  \NC \NR
+\NC align_set     \NC alignment cell                                  \NC \NR
+\NC fin_row       \NC alignment row                                   \NC \NR
+\stoptabulate
+
+As for all the callbacks that deal with nodes, the return value can be one of
+three things:
+
+\startitemize
+\startitem
+    boolean \type {true} signals succesful processing
+\stopitem
+\startitem
+    \type {<node>} signals that the \quote {head} node should be replaced by the
+    returned node
+\stopitem
+\startitem
+    boolean \type {false} signals that the \quote {head} node list should be
+    ignored and flushed from memory
+\stopitem
+\stopitemize
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {linebreak_filter}}
+
+This callback replaces \LUATEX's line breaking algorithm.
+
+\startfunctioncall
+function(<node> head, <boolean> is_display)
+    return <node> newhead
+end
+\stopfunctioncall
+
+The returned node is the head of the list that will be added to the main vertical
+list, the boolean argument is true if this paragraph is interrupted by a
+following math display.
+
+If you return something that is not a \type {<node>}, \LUATEX\ will apply the
+internal linebreak algorithm on the list that starts at \type {<head>}.
+Otherwise, the \type {<node>} you return is supposed to be the head of a list of
+nodes that are all allowed in vertical mode, and at least one of those has to
+represent a hbox. Failure to do so will result in a fatal error.
+
+Setting this callback to \type {false} is possible, but dangerous, because it is
+possible you will end up in an unfixable \quote {deadcycles loop}.
+
+\subsubsection{\type {post_linebreak_filter}}
+
+This callback is called just after \LUATEX\ has converted a list of nodes into a
+stack of \type {\hbox}es.
+
+\startfunctioncall
+function(<node> head, <string> groupcode)
+    return true | false | <node> newhead
+end
+\stopfunctioncall
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {hpack_filter}}
+
+This callback is called when \TEX\ is ready to start boxing some horizontal mode
+material. Math items and line boxes are ignored at the moment.
+
+\startfunctioncall
+function(<node> head, <string> groupcode, <number> size,
+         <string> packtype [, <string> direction])
+    return true | false | <node> newhead
+end
+\stopfunctioncall
+
+The \type {packtype} is either \type {additional} or \type {exactly}. If \type
+{additional}, then the \type {size} is a \type {\hbox spread ...} argument. If
+\type {exactly}, then the \type {size} is a \type {\hbox to ...}. In both cases,
+the number is in scaled points.
+
+The \type {direction} is either one of the three-letter direction specifier
+strings, or \type {nil}.
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {vpack_filter}}
+
+This callback is called when \TEX\ is ready to start boxing some vertical mode
+material. Math displays are ignored at the moment.
+
+This function is very similar to the \type {hpack_filter}. Besides the fact
+that it is called at different moments, there is an extra variable that matches
+\TEX's \type {\maxdepth} setting.
+
+\startfunctioncall
+function(<node> head, <string> groupcode, <number> size, <string>
+         packtype,  <number> maxdepth [, <string> direction])
+    return true | false | <node> newhead
+end
+\stopfunctioncall
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {pre_output_filter}}
+
+This callback is called when \TEX\ is ready to start boxing the box 255 for \type
+{\output}.
+
+\startfunctioncall
+function(<node> head, <string> groupcode, <number> size, <string> packtype,
+        <number> maxdepth [, <string> direction])
+    return true | false | <node> newhead
+end
+\stopfunctioncall
+
+This callback does not replace any internal code.
+
+\subsubsection{\type {hyphenate}}
+
+\startfunctioncall
+function(<node> head, <node> tail)
+end
+\stopfunctioncall
+
+No return values. This callback has to insert discretionary nodes in the node
+list it receives.
+
+Setting this callback to \type {false} will prevent the internal discretionary
+insertion pass.
+
+\subsubsection{\type {ligaturing}}
+
+\startfunctioncall
+function(<node> head, <node> tail)
+end
+\stopfunctioncall
+
+No return values. This callback has to apply ligaturing to the node list it
+receives.
+
+You don't have to worry about return values because the \type {head} node that is
+passed on to the callback is guaranteed not to be a glyph_node (if need be, a
+temporary node will be prepended), and therefore it cannot be affected by the
+mutations that take place. After the callback, the internal value of the \quote
+{tail of the list} will be recalculated.
+
+The \type {next} of \type {head} is guaranteed to be non-nil.
+
+The \type {next} of \type {tail} is guaranteed to be nil, and therefore the
+second callback argument can often be ignored. It is provided for orthogonality,
+and because it can sometimes be handy when special processing has to take place.
+
+Setting this callback to \type {false} will prevent the internal ligature
+creation pass.
+
+\subsubsection{\type {kerning}}
+
+\startfunctioncall
+function(<node> head, <node> tail)
+end
+\stopfunctioncall
+
+No return values. This callback has to apply kerning between the nodes in the
+node list it receives. See \type {ligaturing} for calling conventions.
+
+Setting this callback to \type {false} will prevent the internal kern insertion
+pass.
+
+\subsubsection{\type {mlist_to_hlist}}
+
+This callback replaces \LUATEX's math list to node list conversion algorithm.
+
+\startfunctioncall
+function(<node> head, <string> display_type, <boolean> need_penalties)
+    return <node> newhead
+end
+\stopfunctioncall
+
+The returned node is the head of the list that will be added to the vertical or
+horizontal list, the string argument is either \quote {text} or \quote {display}
+depending on the current math mode, the boolean argument is \type {true} if
+penalties have to be inserted in this list, \type {false} otherwise.
+
+Setting this callback to \type {false} is bad, it will almost certainly result in
+an endless loop.
+
+\subsection{Information reporting callbacks}
+
+\subsubsection{\type {pre_dump}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+This function is called just before dumping to a format file starts. It does not
+replace any code and there are neither arguments nor return values.
+
+\subsubsection{\type {start_run}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+This callback replaces the code that prints \LUATEX's banner. Note that for
+successful use, this callback has to be set in the lua initialization script,
+otherwise it will be seen only after the run has already started.
+
+\subsubsection{\type {stop_run}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+This callback replaces the code that prints \LUATEX's statistics and \quote
+{output written to} messages.
+
+\subsubsection{\type {start_page_number}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+Replaces the code that prints the \type {[} and the page number at the begin of
+\type {\shipout}. This callback will also override the printing of box information
+that normally takes place when \type {\tracingoutput} is positive.
+
+\subsubsection{\type {stop_page_number}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+Replaces the code that prints the \type {]} at the end of \type {\shipout}.
+
+\subsubsection{\type {show_error_hook}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+This callback is run from inside the \TEX\ error function, and the idea is to
+allow you to do some extra reporting on top of what \TEX\ already does (none of
+the normal actions are removed). You may find some of the values in the \type
+{status} table useful.
+
+This callback does not replace any internal code.
+
+\iffalse % this has been retracted for the moment
+
+    \startitemize
+
+    \sym{message}
+
+    is the formal error message \TEX\ has given to the user. (the line after the
+    \type {'!'}).
+
+    \sym{indicator}
+
+    is either a filename (when it is a string) or a location indicator (a number)
+    that can mean lots of different things like a token list id or a \type {\read}
+    number.
+
+    \sym{lineno}
+
+    is the current line number.
+    \stopitemize
+
+    This is an investigative item for 'testing the water' only. The final goal is the
+    total replacement of \TEX's error handling routines, but that needs lots of
+    adjustments in the web source because \TEX\ deals with errors in a somewhat
+    haphazard fashion. This is why the exact definition of \type {indicator} is not
+    given here.
+
+\fi
+
+\subsubsection{\type {show_error_message}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+This callback replaces the code that prints the error message. The usual
+interaction after the message is not affected.
+
+\subsubsection{\type {show_lua_error_hook}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+This callback replaces the code that prints the extra lua error message.
+
+\subsubsection{\type {start_file}}
+
+\startfunctioncall
+function(category,filename)
+end
+\stopfunctioncall
+
+This callback replaces the code that prints \LUATEX's when a file is opened like
+\type {(filename} for regular files. The category is a number:
+
+\starttabulate[|||]
+\NC 1 \NC a normal data file, like a \TEX\ source \NC \NR
+\NC 2 \NC a font map coupling font names to resources \NC \NR
+\NC 3 \NC an image file (\type {png}, \type {pdf}, etc) \NC \NR
+\NC 4 \NC an embedded font subset \NC \NR
+\NC 5 \NC a fully embedded font \NC \NR
+\stoptabulate
+
+\subsubsection{\type {stop_file}}
+
+\startfunctioncall
+function(category)
+end
+\stopfunctioncall
+
+This callback replaces the code that prints \LUATEX's when a file is closed like
+the \type {)} for regular files.
+
+\subsection{PDF-related callbacks}
+
+\subsubsection{\type {finish_pdffile}}
+
+\startfunctioncall
+function()
+end
+\stopfunctioncall
+
+This callback is called when all document pages are already written to the \PDF\
+file and \LUATEX\ is about to finalize the output document structure. Its
+intended use is final update of \PDF\ dictionaries such as \type {/Catalog} or
+\type {/Info}. The callback does not replace any code. There are neither
+arguments nor return values.
+
+\subsubsection{\type {finish_pdfpage}}
+
+\startfunctioncall
+function(shippingout)
+end
+\stopfunctioncall
+
+This callback is called after the pdf page stream has been assembled and before
+the page object gets finalized.
+
+\subsection{Font-related callbacks}
+
+\subsubsection{\type {define_font}}
+
+\startfunctioncall
+function(<string> name, <number> size, <number> id)
+    return <table> font | <number> id
+end
+\stopfunctioncall
+
+The string \type {name} is the filename part of the font specification, as given
+by the user.
+
+The number \type {size} is a bit special:
+
+\startitemize[packed]
+\startitem
+    If it is positive, it specifies an \quote{at size} in scaled points.
+\stopitem
+\startitem
+    If it is negative, its absolute value represents a \quote {scaled} setting
+    relative to the designsize of the font.
+\stopitem
+\stopitemize
+
+The \type {id} is the internal number assigned to the font.
+
+The internal structure of the \type {font} table that is to be returned is
+explained in \in {chapter} [fonts]. That table is saved internally, so you can
+put extra fields in the table for your later \LUA\ code to use. In alternative,
+retval can be a previously defined fontid. This is useful if a previous
+definition can be reused instead of creating a whole new font structure.
+
+Setting this callback to \type {false} is pointless as it will prevent font
+loading completely but will nevertheless generate errors.
+
+\section{The \type {epdf} library}
+
+The \type {epdf} library provides Lua bindings to many \PDF\ access functions
+that are defined by the poppler pdf viewer library (written in C$+{}+$ by
+Kristian H\o gsberg, based on xpdf by Derek Noonburg). Within \LUATEX\ (and
+\PDFTEX), xpdf functionality is being used since long time to embed \PDF\ files.
+The \type {epdf} library shall allow to scrutinize an external \PDF\ file. It
+gives access to its document structure, e.g., catalog, cross-reference table,
+individual pages, objects, annotations, info, and metadata. The \LUATEX\ team is
+evaluating the possibility of reducing the binding to a basic low level \PDF\
+primitives and delegate the complete set of functions to an external shared
+object module.
+
+The \type {epdf} library is still in alpha state: \PDF\ access is currently
+read|-|only. Iit's not yet possible to alter a \PDF\ file or to assemble it from
+scratch, and many function bindings are still missing, and it is unlikely that we
+to support that at all. At some point we might also decide to limit the interface
+to a reasonable subset.
+
+For a start, a \PDF\ file is opened by \type {epdf.open()} with file name, e.g.:
+
+\starttyping
+doc = epdf.open("foo.pdf")
+\stoptyping
+
+This normally returns a \type {PDFDoc} userdata variable; but if the file could
+not be opened successfully, instead of a fatal error just the value \type {nil} is
+returned.
+
+All Lua functions in the \type {epdf} library are named after the poppler
+functions listed in the poppler header files for the various classes, e.g., files
+\type {PDFDoc.h}, \type {Dict.h}, and \type {Array.h}. These files can be found
+in the poppler subdirectory within the \LUATEX\ sources. Which functions are
+already implemented in the \type {epdf} library can be found in the \LUATEX\
+source file \type {lepdflib.cc}. For using the \type {epdf} library, knowledge of
+the \PDF\ file architecture is indispensable.
+
+There are many different userdata types defined by the \type {epdf} library,
+currently these are \type {AnnotBorderStyle}, \type {AnnotBorder}, \type
+{Annots}, \type {Annot}, \type {Array}, \type {Attribute}, \type {Catalog}, \type
+{Dict}, \type {EmbFile}, \type {GString}, \type {LinkDest}, \type {Links}, \type
+{Link}, \type {ObjectStream}, \type {Object}, \type {PDFDoc}, \type
+{PDFRectangle}, \type {Page}, \type {Ref}, \type {Stream}, \type {StructElement},
+\type {StructTreeRoot} \type {TextSpan}, \type {XRefEntry} and \type {XRef}.
+
+All these userdata names and the Lua access functions closely resemble the
+classes naming from the poppler header files, including the choice of mixed upper
+and lower case letters. The Lua function calls use object|-|oriented syntax,
+e.g., the following calls return the \type {Page} object for page~1:
+
+\starttyping
+pageref = doc:getCatalog():getPageRef(1)
+pageobj = doc:getXRef():fetch(pageref.num, pageref.gen)
+\stoptyping
+
+But writing such chained calls is risky, as an intermediate function may return
+\type {nil} on error; therefore between function calls there should be Lua type
+checks (e.g., against \type {nil}) done. If a non-object item is requested (e.g.,
+a \type {Dict} item by calling \type {page:getPieceInfo()}, cf.~\type {Page.h})
+but not available, the Lua functions return \type {nil} (without error). If a
+function should return an \type {Object}, but it's not existing, a \type {Null}
+object is returned instead (also without error; this is in|-|line with poppler
+behavior).
+
+All library objects have a \type {__gc} metamethod for garbage collection. The
+\type {__tostring} metamethod gives the type name for each object.
+
+All object constructors:
+
+\startfunctioncall
+<PDFDoc>       = epdf.open(<string> PDF filename)
+<Annot>        = epdf.Annot(<XRef>, <Dict>, <Catalog>, <Ref>)
+<Annots>       = epdf.Annots(<XRef>, <Catalog>, <Object>)
+<Array>        = epdf.Array(<XRef>)
+<Attribute>    = epdf.Attribute(<Type>,<Object>)| epdf.Attribute(<string>, <int>, <Object>)
+<Dict>         = epdf.Dict(<XRef>)
+<Object>       = epdf.Object()
+<PDFRectangle> = epdf.PDFRectangle()
+\stopfunctioncall
+
+The functions \type {StructElement_Type}, \type {Attribute_Type} and \type
+{AttributeOwner_Type} return a hash table \type {{<string>,<integer>}}.
+
+\type {Annot} methods:
+
+\startfunctioncall
+<boolean>     = <Annot>:isOK()
+<Object>      = <Annot>:getAppearance()
+<AnnotBorder> = <Annot>:getBorder()
+<boolean>     = <Annot>:match(<Ref>)
+\stopfunctioncall
+
+\type {AnnotBorderStyle} methods:
+
+\startfunctioncall
+<number> = <AnnotBorderStyle>:getWidth()
+\stopfunctioncall
+
+\type {Annots} methods:
+
+\startfunctioncall
+<integer> = <Annots>:getNumAnnots()
+<Annot>   = <Annots>:getAnnot(<integer>)
+\stopfunctioncall
+
+\type {Array} methods:
+
+\startfunctioncall
+            <Array>:incRef()
+            <Array>:decRef()
+<integer> = <Array>:getLength()
+            <Array>:add(<Object>)
+<Object>  = <Array>:get(<integer>)
+<Object>  = <Array>:getNF(<integer>)
+<string>  = <Array>:getString(<integer>)
+\stopfunctioncall
+
+\type {Attribute} methods:
+
+\startfunctioncall
+<boolean>  = <Attribute>:isOk()
+<integer>  = <Attribute>:getType()
+<integer>  = <Attribute>:getOwner()
+<string>   = <Attribute>:getTypeName()
+<string>   = <Attribute>:getOwnerName()
+<Object>   = <Attribute>:getValue()
+<Object>   = <Attribute>:getDefaultValue
+<string>   = <Attribute>:getName()
+<integer>  = <Attribute>:getRevision()
+             <Attribute>:setRevision(<unsigned integer>)
+<boolean>  = <Attribute>:istHidden()
+             <Attribute>:setHidden(<boolean>)
+<string>   = <Attribute>:getFormattedValue()
+<string>   = <Attribute>:setFormattedValue(<string>)
+\stopfunctioncall
+
+\type {Catalog} methods:
+
+\startfunctioncall
+<boolean>  = <Catalog>:isOK()
+<integer>  = <Catalog>:getNumPages()
+<Page>     = <Catalog>:getPage(<integer>)
+<Ref>      = <Catalog>:getPageRef(<integer>)
+<string>   = <Catalog>:getBaseURI()
+<string>   = <Catalog>:readMetadata()
+<Object>   = <Catalog>:getStructTreeRoot()
+<integer>  = <Catalog>:findPage(<integer> object number, <integer> object generation)
+<LinkDest> = <Catalog>:findDest(<string> name)
+<Object>   = <Catalog>:getDests()
+<integer>  = <Catalog>:numEmbeddedFiles()
+<EmbFile>  = <Catalog>:embeddedFile(<integer>)
+<integer>  = <Catalog>:numJS()
+<string>   = <Catalog>:getJS(<integer>)
+<Object>   = <Catalog>:getOutline()
+<Object>   = <Catalog>:getAcroForm()
+\stopfunctioncall
+
+\type {EmbFile} methods:
+
+\startfunctioncall
+<string>   = <EmbFile>:name()
+<string>   = <EmbFile>:description()
+<integer>  = <EmbFile>:size()
+<string>   = <EmbFile>:modDate()
+<string>   = <EmbFile>:createDate()
+<string>   = <EmbFile>:checksum()
+<string>   = <EmbFile>:mimeType()
+<Object>   = <EmbFile>:streamObject()
+<boolean>  = <EmbFile>:isOk()
+\stopfunctioncall
+
+\type {Dict} methods:
+
+\startfunctioncall
+            <Dict>:incRef()
+            <Dict>:decRef()
+<integer> = <Dict>:getLength()
+            <Dict>:add(<string>, <Object>)
+            <Dict>:set(<string>, <Object>)
+            <Dict>:remove(<string>)
+<boolean> = <Dict>:is(<string>)
+<Object>  = <Dict>:lookup(<string>)
+<Object>  = <Dict>:lookupNF(<string>)
+<integer> = <Dict>:lookupInt(<string>, <string>)
+<string>  = <Dict>:getKey(<integer>)
+<Object>  = <Dict>:getVal(<integer>)
+<Object>  = <Dict>:getValNF(<integer>)
+<boolean> = <Dict>:hasKey(<string>)
+\stopfunctioncall
+
+\type {Link} methods:
+
+\startfunctioncall
+<boolean>  = <Link>:isOK()
+<boolean>  = <Link>:inRect(<number>, <number>)
+\stopfunctioncall
+
+\type {LinkDest} methods:
+
+\startfunctioncall
+<boolean>  = <LinkDest>:isOK()
+<integer>  = <LinkDest>:getKind()
+<string>   = <LinkDest>:getKindName()
+<boolean>  = <LinkDest>:isPageRef()
+<integer>  = <LinkDest>:getPageNum()
+<Ref>      = <LinkDest>:getPageRef()
+<number>   = <LinkDest>:getLeft()
+<number>   = <LinkDest>:getBottom()
+<number>   = <LinkDest>:getRight()
+<number>   = <LinkDest>:getTop()
+<number>   = <LinkDest>:getZoom()
+<boolean>  = <LinkDest>:getChangeLeft()
+<boolean>  = <LinkDest>:getChangeTop()
+<boolean>  = <LinkDest>:getChangeZoom()
+\stopfunctioncall
+
+\type {Links} methods:
+
+\startfunctioncall
+<integer>  = <Links>:getNumLinks()
+<Link>     = <Links>:getLink(<integer>)
+\stopfunctioncall
+
+\type {Object} methods:
+
+\startfunctioncall
+            <Object>:initBool(<boolean>)
+            <Object>:initInt(<integer>)
+            <Object>:initReal(<number>)
+            <Object>:initString(<string>)
+            <Object>:initName(<string>)
+            <Object>:initNull()
+            <Object>:initArray(<XRef>)
+            <Object>:initDict(<XRef>)
+            <Object>:initStream(<Stream>)
+            <Object>:initRef(<integer> object number, <integer> object generation)
+            <Object>:initCmd(<string>)
+            <Object>:initError()
+            <Object>:initEOF()
+<Object>  = <Object>:fetch(<XRef>)
+<integer> = <Object>:getType()
+<string>  = <Object>:getTypeName()
+<boolean> = <Object>:isBool()
+<boolean> = <Object>:isInt()
+<boolean> = <Object>:isReal()
+<boolean> = <Object>:isNum()
+<boolean> = <Object>:isString()
+<boolean> = <Object>:isName()
+<boolean> = <Object>:isNull()
+<boolean> = <Object>:isArray()
+<boolean> = <Object>:isDict()
+<boolean> = <Object>:isStream()
+<boolean> = <Object>:isRef()
+<boolean> = <Object>:isCmd()
+<boolean> = <Object>:isError()
+<boolean> = <Object>:isEOF()
+<boolean> = <Object>:isNone()
+<boolean> = <Object>:getBool()
+<integer> = <Object>:getInt()
+<number>  = <Object>:getReal()
+<number>  = <Object>:getNum()
+<string>  = <Object>:getString()
+<string>  = <Object>:getName()
+<Array>   = <Object>:getArray()
+<Dict>    = <Object>:getDict()
+<Stream>  = <Object>:getStream()
+<Ref>     = <Object>:getRef()
+<integer> = <Object>:getRefNum()
+<integer> = <Object>:getRefGen()
+<string>  = <Object>:getCmd()
+<integer> = <Object>:arrayGetLength()
+          = <Object>:arrayAdd(<Object>)
+<Object>  = <Object>:arrayGet(<integer>)
+<Object>  = <Object>:arrayGetNF(<integer>)
+<integer> = <Object>:dictGetLength(<integer>)
+          = <Object>:dictAdd(<string>, <Object>)
+          = <Object>:dictSet(<string>, <Object>)
+<Object>  = <Object>:dictLookup(<string>)
+<Object>  = <Object>:dictLookupNF(<string>)
+<string>  = <Object>:dictgetKey(<integer>)
+<Object>  = <Object>:dictgetVal(<integer>)
+<Object>  = <Object>:dictgetValNF(<integer>)
+<boolean> = <Object>:streamIs(<string>)
+          = <Object>:streamReset()
+<integer> = <Object>:streamGetChar()
+<integer> = <Object>:streamLookChar()
+<integer> = <Object>:streamGetPos()
+          = <Object>:streamSetPos(<integer>)
+<Dict>    = <Object>:streamGetDict()
+\stopfunctioncall
+
+\type {Page} methods:
+
+\startfunctioncall
+<boolean>      = <Page>:isOk()
+<integer>      = <Page>:getNum()
+<PDFRectangle> = <Page>:getMediaBox()
+<PDFRectangle> = <Page>:getCropBox()
+<boolean>      = <Page>:isCropped()
+<number>       = <Page>:getMediaWidth()
+<number>       = <Page>:getMediaHeight()
+<number>       = <Page>:getCropWidth()
+<number>       = <Page>:getCropHeight()
+<PDFRectangle> = <Page>:getBleedBox()
+<PDFRectangle> = <Page>:getTrimBox()
+<PDFRectangle> = <Page>:getArtBox()
+<integer>      = <Page>:getRotate()
+<string>       = <Page>:getLastModified()
+<Dict>         = <Page>:getBoxColorInfo()
+<Dict>         = <Page>:getGroup()
+<Stream>       = <Page>:getMetadata()
+<Dict>         = <Page>:getPieceInfo()
+<Dict>         = <Page>:getSeparationInfo()
+<Dict>         = <Page>:getResourceDict()
+<Object>       = <Page>:getAnnots()
+<Links>        = <Page>:getLinks(<Catalog>)
+<Object>       = <Page>:getContents()
+\stopfunctioncall
+
+\type {PDFDoc} methods:
+
+\startfunctioncall
+<boolean>  = <PDFDoc>:isOk()
+<integer>  = <PDFDoc>:getErrorCode()
+<string>   = <PDFDoc>:getErrorCodeName()
+<string>   = <PDFDoc>:getFileName()
+<XRef>     = <PDFDoc>:getXRef()
+<Catalog>  = <PDFDoc>:getCatalog()
+<number>   = <PDFDoc>:getPageMediaWidth()
+<number>   = <PDFDoc>:getPageMediaHeight()
+<number>   = <PDFDoc>:getPageCropWidth()
+<number>   = <PDFDoc>:getPageCropHeight()
+<integer>  = <PDFDoc>:getNumPages()
+<string>   = <PDFDoc>:readMetadata()
+<Object>   = <PDFDoc>:getStructTreeRoot()
+<integer>  = <PDFDoc>:findPage(<integer> object number, <integer> object generation)
+<Links>    = <PDFDoc>:getLinks(<integer>)
+<LinkDest> = <PDFDoc>:findDest(<string>)
+<boolean>  = <PDFDoc>:isEncrypted()
+<boolean>  = <PDFDoc>:okToPrint()
+<boolean>  = <PDFDoc>:okToChange()
+<boolean>  = <PDFDoc>:okToCopy()
+<boolean>  = <PDFDoc>:okToAddNotes()
+<boolean>  = <PDFDoc>:isLinearized()
+<Object>   = <PDFDoc>:getDocInfo()
+<Object>   = <PDFDoc>:getDocInfoNF()
+<integer>  = <PDFDoc>:getPDFMajorVersion()
+<integer>  = <PDFDoc>:getPDFMinorVersion()
+\stopfunctioncall
+
+\type {PDFRectangle} methods:
+
+\startfunctioncall
+<boolean>  = <PDFRectangle>:isValid()
+\stopfunctioncall
+
+%\type {Ref} methods:
+%
+%\startfunctioncall
+%\stopfunctioncall
+
+\type {Stream} methods:
+
+\startfunctioncall
+<integer>  = <Stream>:getKind()
+<string>   = <Stream>:getKindName()
+           = <Stream>:reset()
+           = <Stream>:close()
+<integer>  = <Stream>:getChar()
+<integer>  = <Stream>:lookChar()
+<integer>  = <Stream>:getRawChar()
+<integer>  = <Stream>:getUnfilteredChar()
+           = <Stream>:unfilteredReset()
+<integer>  = <Stream>:getPos()
+<boolean>  = <Stream>:isBinary()
+<Stream>   = <Stream>:getUndecodedStream()
+<Dict>     = <Stream>:getDict()
+\stopfunctioncall
+
+\type {StructElement} methods:
+
+\startfunctioncall
+<string>         = <StructElement>:getTypeName()
+<integer>        = <StructElement>:getType()
+<boolean>        = <StructElement>:isOk()
+<boolean>        = <StructElement>:isBlock()
+<boolean>        = <StructElement>:isInline()
+<boolean>        = <StructElement>:isGrouping()
+<boolean>        = <StructElement>:isContent()
+<boolean>        = <StructElement>:isObjectRef()
+<integer>        = <StructElement>:getMCID()
+<Ref>            = <StructElement>:getObjectRef()
+<Ref>            = <StructElement>:getParentRef()
+<boolean>        = <StructElement>:hasPageRef()
+<Ref>            = <StructElement>:getPageRef()
+<StructTreeRoot> = <StructElement>:getStructTreeRoot()
+<string>         = <StructElement>:getID()
+<string>         = <StructElement>:getLanguage()
+<integer>        = <StructElement>:getRevision()
+                   <StructElement>:setRevision(<unsigned integer>)
+<string>         = <StructElement>:getTitle()
+<string>         = <StructElement>:getExpandedAbbr()
+<integer>        = <StructElement>:getNumChildren()
+<StructElement>  = <StructElement>:getChild()
+                 = <StructElement>:appendChild<StructElement>)
+<integer>        = <StructElement>:getNumAttributes()
+<Attribute>      = <StructElement>:geAttribute(<integer>)
+<string>         = <StructElement>:appendAttribute(<Attribute>)
+<Attribute>      = <StructElement>:findAttribute(<Attribute::Type>,boolean,Attribute::Owner)
+<string>         = <StructElement>:getAltText()
+<string>         = <StructElement>:getActualText()
+<string>         = <StructElement>:getText(<boolean>)
+<table>          = <StructElement>:getTextSpans()
+\stopfunctioncall
+
+\type {StructTreeRoot} methods:
+
+\startfunctioncall
+<StructElement> = <StructTreeRoot>:findParentElement
+<PDFDoc>        = <StructTreeRoot>:getDoc
+<Dict>          = <StructTreeRoot>:getRoleMap
+<Dict>          = <StructTreeRoot>:getClassMap
+<integer>       = <StructTreeRoot>:getNumChildren
+<StructElement> = <StructTreeRoot>:getChild
+                  <StructTreeRoot>:appendChild
+<StructElement> = <StructTreeRoot>:findParentElement
+\stopfunctioncall
+
+\type {TextSpan} han only one method:
+
+\startfunctioncall
+<string> = <TestSpan>:getText()
+\stopfunctioncall
+
+\type {XRef} methods:
+
+\startfunctioncall
+<boolean>  = <XRef>:isOk()
+<integer>  = <XRef>:getErrorCode()
+<boolean>  = <XRef>:isEncrypted()
+<boolean>  = <XRef>:okToPrint()
+<boolean>  = <XRef>:okToPrintHighRes()
+<boolean>  = <XRef>:okToChange()
+<boolean>  = <XRef>:okToCopy()
+<boolean>  = <XRef>:okToAddNotes()
+<boolean>  = <XRef>:okToFillForm()
+<boolean>  = <XRef>:okToAccessibility()
+<boolean>  = <XRef>:okToAssemble()
+<Object>   = <XRef>:getCatalog()
+<Object>   = <XRef>:fetch(<integer> object number, <integer> object generation)
+<Object>   = <XRef>:getDocInfo()
+<Object>   = <XRef>:getDocInfoNF()
+<integer>  = <XRef>:getNumObjects()
+<integer>  = <XRef>:getRootNum()
+<integer>  = <XRef>:getRootGen()
+<integer>  = <XRef>:getSize()
+<Object>   = <XRef>:getTrailerDict()
+\stopfunctioncall
+
+There is an experimental function \type {epdf.openMemStream} that takes three
+arguments:
+
+\starttabulate
+\NC \type {stream}  \NC this is a (in low level \LUA\ speak) light userdata
+                        object, i.e.\ a pointer to a sequence of bytes \NC \NR
+\NC \type {length}  \NC this is the length of the stream in bytes \NC \NR
+\NC \type {name}    \NC this is a unique identifier that us used for hashing the
+                        stream, so that mulltiple doesn't use more memory \NC \NR
+\stoptabulate
+
+Instead of a light userdata stream you can also pass a \LUA\ string, in which
+case the given length is (at most) the string length.
+
+The returned object can be used in the \type {img} library instead of a filename.
+Both the memory stream and it's use in the image library is experimental and can
+change. In case you wonder where this can be used: when you use the swiglib
+library for graphic magick, it can return such a userdata object. This permits
+conversion in memory and passing the result directly to the backend. This might
+save some runtime in one|-|pass workflows. This feature is currently not meant
+for production.
+
+%***********************************************************************
+
+\section{The \type {font} library}
+
+The font library provides the interface into the internals of the font system,
+and also it contains helper functions to load traditional \TEX\ font metrics
+formats. Other font loading functionality is provided by the \type {fontloader}
+library that will be discussed in the next section.
+
+\subsection{Loading a \TFM\ file}
+
+The behavior documented in this subsection is considered stable in the sense that
+there will not be backward-incompatible changes any more.
+
+\startfunctioncall
+<table> fnt = font.read_tfm(<string> name, <number> s)
+\stopfunctioncall
+
+The number is a bit special:
+
+\startitemize
+\startitem
+    If it is positive, it specifies an \quote {at size} in scaled points.
+\stopitem
+\startitem
+    If it is negative, its absolute value represents a \quote {scaled}
+    setting relative to the designsize of the font.
+\stopitem
+\stopitemize
+
+The internal structure of the metrics font table that is returned is explained in
+\in {chapter} [fonts].
+
+\subsection{Loading a \VF\ file}
+
+The behavior documented in this subsection is considered stable in the sense that
+there will not be backward-incompatible changes any more.
+
+\startfunctioncall
+<table> vf_fnt = font.read_vf(<string> name, <number> s)
+\stopfunctioncall
+
+The meaning of the number \type {s} and the format of the returned table are
+similar to the ones in the \type {read_tfm()} function.
+
+\subsection{The fonts array}
+
+The whole table of \TEX\ fonts is accessible from \LUA\ using a virtual array.
+
+\starttyping
+font.fonts[n] = { ... }
+<table> f = font.fonts[n]
+\stoptyping
+
+See \in {chapter} [fonts] for the structure of the tables. Because this is a
+virtual array, you cannot call \type {pairs} on it, but see below for the \type
+{font.each} iterator.
+
+The two metatable functions implementing the virtual array are:
+
+\startfunctioncall
+<table> f = font.getfont(<number> n)
+font.setfont(<number> n, <table> f)
+\stopfunctioncall
+
+Note that at the moment, each access to the \type {font.fonts} or call to \type
+{font.getfont} creates a lua table for the whole font. This process can be quite
+slow. In a later version of \LUATEX, this interface will change (it will start
+using userdata objects instead of actual tables).
+
+Also note the following: assignments can only be made to fonts that have already
+been defined in \TEX, but have not been accessed {\it at all\/} since that
+definition. This limits the usability of the write access to \type {font.fonts}
+quite a lot, a less stringent ruleset will likely be implemented later.
+
+\subsection{Checking a font's status}
+
+You can test for the status of a font by calling this function:
+
+\startfunctioncall
+<boolean> f = font.frozen(<number> n)
+\stopfunctioncall
+
+The return value is one of \type {true} (unassignable), \type {false} (can be
+changed) or \type {nil} (not a valid font at all).
+
+\subsection{Defining a font directly}
+
+You can define your own font into \type {font.fonts} by calling this function:
+
+\startfunctioncall
+<number> i = font.define(<table> f)
+\stopfunctioncall
+
+The return value is the internal id number of the defined font (the index into
+\type {font.fonts}). If the font creation fails, an error is raised. The table
+is a font structure, as explained in \in {chapter} [fonts].
+
+\subsection{Projected next font id}
+
+\startfunctioncall
+<number> i = font.nextid()
+\stopfunctioncall
+
+This returns the font id number that would be returned by a \type {font.define}
+call if it was executed at this spot in the code flow. This is useful for virtual
+fonts that need to reference themselves.
+
+\subsection{Font id}
+
+\startfunctioncall
+<number> i = font.id(<string> csname)
+\stopfunctioncall
+
+This returns the font id associated with \type {csname} string, or $-1$ if \type
+{csname} is not defined.
+
+\subsection{Currently active font}
+
+\startfunctioncall
+<number> i = font.current()
+font.current(<number> i)
+\stopfunctioncall
+
+This gets or sets the currently used font number.
+
+\subsection{Maximum font id}
+
+\startfunctioncall
+<number> i = font.max()
+\stopfunctioncall
+
+This is the largest used index in \type {font.fonts}.
+
+\subsection{Iterating over all fonts}
+
+\startfunctioncall
+for i,v in font.each() do
+  ...
+end
+\stopfunctioncall
+
+This is an iterator over each of the defined \TEX\ fonts. The first returned
+value is the index in \type {font.fonts}, the second the font itself, as a \LUA\
+table. The indices are listed incrementally, but they do not always form an array
+of consecutive numbers: in some cases there can be holes in the sequence.
+
+\section{The \type {fontloader} library}
+
+\subsection{Getting quick information on a font}
+
+\startfunctioncall
+<table> info = fontloader.info(<string> filename)
+\stopfunctioncall
+
+This function returns either \type {nil}, or a \type {table}, or an array of
+small tables (in the case of a TrueType collection). The returned table(s) will
+contain some fairly interesting information items from the font(s) defined by the
+file:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key    \NC \bf type \NC \bf explanation \NC \NR
+\NC fontname     \NC string   \NC the \POSTSCRIPT\ name of the font\NC \NR
+\NC fullname     \NC string   \NC the formal name of the font\NC \NR
+\NC familyname   \NC string   \NC the family name this font belongs to\NC \NR
+\NC weight       \NC string   \NC a string indicating the color value of the font\NC \NR
+\NC version      \NC string   \NC the internal font version\NC \NR
+\NC italicangle  \NC float    \NC the slant angle\NC \NR
+\NC units_per_em \NC number   \NC 1000 for \POSTSCRIPT-based fonts, usually 2048 for \TRUETYPE\NC \NR
+\NC pfminfo      \NC table    \NC (see \in{section}[fontloaderpfminfotable])\NC \NR
+\stoptabulate
+
+Getting information through this function is (sometimes much) more efficient than
+loading the font properly, and is therefore handy when you want to create a
+dictionary of available fonts based on a directory contents.
+
+\subsection{Loading an \OPENTYPE\ or \TRUETYPE\ file}
+If you want to use an \OPENTYPE\ font, you have to get the metric information
+from somewhere. Using the \type {fontloader} library, the simplest way to get
+that information is thus:
+
+\starttyping
+function load_font (filename)
+  local metrics = nil
+  local font = fontloader.open(filename)
+  if font then
+     metrics = fontloader.to_table(font)
+     fontloader.close(font)
+  end
+  return metrics
+end
+
+myfont = load_font('/opt/tex/texmf/fonts/data/arial.ttf')
+\stoptyping
+
+The main function call is
+
+\startfunctioncall
+<userdata> f, <table> w = fontloader.open(<string> filename)
+<userdata> f, <table> w = fontloader.open(<string> filename, <string> fontname)
+\stopfunctioncall
+
+The first return value is a userdata representation of the font. The second
+return value is a table containing any warnings and errors reported by fontloader
+while opening the font. In normal typesetting, you would probably ignore the
+second argument, but it can be useful for debugging purposes.
+
+For \TRUETYPE\ collections (when filename ends in 'ttc') and \DFONT\ collections,
+you have to use a second string argument to specify which font you want from the
+collection. Use the \type {fontname} strings that are returned by \type
+{fontloader.info} for that.
+
+To turn the font into a table, \type {fontloader.to_table} is used on the font
+returned by \type {fontloader.open}.
+
+\startfunctioncall
+<table> f = fontloader.to_table(<userdata> font)
+\stopfunctioncall
+
+This table cannot be used directly by \LUATEX\ and should be turned into another
+one as described in~\in {chapter} [fonts]. Do not forget to store the \type
+{fontname} value in the \type {psname} field of the metrics table to be returned
+to \LUATEX, otherwise the font inclusion backend will not be able to find the
+correct font in the collection.
+
+See \in {section} [fontloadertables] for details on the userdata object returned
+by \type {fontloader.open()} and the layout of the \type {metrics} table returned
+by \type {fontloader.to_table()}.
+
+The font file is parsed and partially interpreted by the font loading routines
+from \FONTFORGE. The file format can be \OPENTYPE, \TRUETYPE, \TRUETYPE\
+Collection, \CFF, or \TYPEONE.
+
+There are a few advantages to this approach compared to reading the actual font
+file ourselves:
+
+\startitemize
+
+\startitem
+    The font is automatically re|-|encoded, so that the \type {metrics} table for
+    \TRUETYPE\ and \OPENTYPE\ fonts is using \UNICODE\ for the character indices.
+\stopitem
+
+\startitem
+    Many features are pre|-|processed into a format that is easier to handle than
+    just the bare tables would be.
+\stopitem
+
+\startitem
+    \POSTSCRIPT|-|based \OPENTYPE\ fonts do not store the character height and
+    depth in the font file, so the character boundingbox has to be calculated in
+    some way.
+\stopitem
+
+\startitem
+    In the future, it may be interesting to allow \LUA\ scripts access to
+    the font program itself, perhaps even creating or changing the font.
+\stopitem
+
+\stopitemize
+
+A loaded font is discarded with:
+
+\startfunctioncall
+fontloader.close(<userdata> font)
+\stopfunctioncall
+
+\subsection{Applying a \quote{feature file}}
+
+You can apply a \quote{feature file} to a loaded font:
+
+\startfunctioncall
+<table> errors = fontloader.apply_featurefile(<userdata> font, <string> filename)
+\stopfunctioncall
+
+A \quote {feature file} is a textual representation of the features in an
+\OPENTYPE\ font. See
+
+\starttyping
+http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html
+\stoptyping
+
+and
+
+\starttyping
+http://fontforge.sourceforge.net/featurefile.html
+\stoptyping
+
+for a more detailed description of feature files.
+
+If the function fails, the return value is a table containing any errors reported
+by fontloader while applying the feature file. On success, \type {nil} is
+returned.
+
+\subsection{Applying an \quote{\AFM\ file}}
+
+You can apply an \quote {\AFM\ file} to a loaded font:
+
+\startfunctioncall
+<table> errors = fontloader.apply_afmfile(<userdata> font, <string> filename)
+\stopfunctioncall
+
+An \AFM\ file is a textual representation of (some of) the meta information
+in a \TYPEONE\ font. See
+
+\starttyping
+ftp://ftp.math.utah.edu/u/ma/hohn/linux/postscript/5004.AFM_Spec.pdf
+\stoptyping
+
+for more information about \AFM\ files.
+
+Note: If you \type {fontloader.open()} a \TYPEONE\ file named \type {font.pfb},
+the library will automatically search for and apply \type {font.afm} if it exists
+in the same directory as the file \type {font.pfb}. In that case, there is no
+need for an explicit call to \type {apply_afmfile()}.
+
+If the function fails, the return value is a table containing any errors reported
+by fontloader while applying the AFM file. On success, \type {nil} is returned.
+
+\subsection[fontloadertables]{Fontloader font tables}
+
+As mentioned earlier, the return value of \type {fontloader.open()} is a userdata
+object. One way to have access to the actual metrics is to call \type
+{fontloader.to_table()} on this object, returning the table structure that is
+explained in the following subsections.
+
+However, it turns out that the result from \type {fontloader.to_table()}
+sometimes needs very large amounts of memory (depending on the font's complexity
+and size) so it is possible to access the userdata object directly.
+
+\startitemize
+\startitem
+    All top|-|level keys that would be returned by \type {to_table()}
+    can also be accessed directly.
+\stopitem
+\startitem
+\startitem
+    The top|-|level key \quote {glyphs} returns a {\it virtual\/} array that
+    allows indices from \type {f.glyphmin} to (\type {f.glyphmax}).
+\stopitem
+\startitem
+    The items in that virtual array (the actual glyphs) are themselves also
+    userdata objects, and each has accessors for all of the keys explained in the
+    section \quote {Glyph items} below.
+\stopitem
+    The top|-|level key \quote {subfonts} returns an {\it actual} array of userdata
+    objects, one for each of the subfonts (or nil, if there are no subfonts).
+\stopitem
+\stopitemize
+
+A short example may be helpful. This code generates a printout of all
+the glyph names in the font \type {PunkNova.kern.otf}:
+
+\starttyping
+local f = fontloader.open('PunkNova.kern.otf')
+print (f.fontname)
+local i = 0
+if f.glyphcnt > 0 then
+    for i=f.glyphmin,f.glyphmax do
+       local g = f.glyphs[i]
+       if g then
+          print(g.name)
+       end
+       i = i + 1
+    end
+end
+fontloader.close(f)
+\stoptyping
+
+In this case, the \LUATEX\ memory requirement stays below 100MB on the test
+computer, while the internal stucture generated by \type {to_table()} needs more
+than 2GB of memory (the font itself is 6.9MB in disk size).
+
+Only the top|-|level font, the subfont table entries, and the glyphs are virtual
+objects, everything else still produces normal lua values and tables.
+
+If you want to know the valid fields in a font or glyph structure, call the \type
+{fields} function on an object of a particular type (either glyph or font):
+
+\startfunctioncall
+<table> fields = fontloader.fields(<userdata> font)
+<table> fields = fontloader.fields(<userdata> font_glyph)
+\stopfunctioncall
+
+For instance:
+
+\startfunctioncall
+local fields = fontloader.fields(f)
+local fields = fontloader.fields(f.glyphs[0])
+\stopfunctioncall
+
+\subsubsection{Table types}
+
+\subsubsubsection{Top-level}
+
+The top|-|level keys in the returned table are (the explanations in this part of
+the documentation are not yet finished):
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key                    \NC \bf type \NC \bf explanation \NC \NR
+\NC table_version                \NC number   \NC indicates the metrics version (currently~0.3)\NC \NR
+\NC fontname                     \NC string   \NC \POSTSCRIPT\ font name\NC \NR
+\NC fullname                     \NC string   \NC official (human-oriented) font name\NC \NR
+\NC familyname                   \NC string   \NC family name\NC \NR
+\NC weight                       \NC string   \NC weight indicator\NC \NR
+\NC copyright                    \NC string   \NC copyright information\NC \NR
+\NC filename                     \NC string   \NC the file name\NC \NR
+\NC version                      \NC string   \NC font version\NC \NR
+\NC italicangle                  \NC float    \NC slant angle\NC \NR
+\NC units_per_em                 \NC number   \NC 1000 for \POSTSCRIPT-based fonts, usually 2048 for \TRUETYPE\NC \NR
+\NC ascent                       \NC number   \NC height of ascender in \type {units_per_em}\NC \NR
+\NC descent                      \NC number   \NC depth of descender in \type {units_per_em}\NC \NR
+\NC upos                         \NC float    \NC \NC \NR
+\NC uwidth                       \NC float    \NC \NC \NR
+\NC uniqueid                     \NC number   \NC \NC \NR
+\NC glyphs                       \NC array    \NC \NC \NR
+\NC glyphcnt                     \NC number   \NC number of included glyphs\NC \NR
+\NC glyphmax                     \NC number   \NC maximum used index the glyphs array\NC \NR
+\NC glyphmin                     \NC number   \NC minimum used index the glyphs array\NC \NR
+\NC hasvmetrics                  \NC number   \NC \NC \NR
+\NC onlybitmaps                  \NC number   \NC \NC \NR
+\NC serifcheck                   \NC number   \NC \NC \NR
+\NC isserif                      \NC number   \NC \NC \NR
+\NC issans                       \NC number   \NC \NC \NR
+\NC encodingchanged              \NC number   \NC \NC \NR
+\NC strokedfont                  \NC number   \NC \NC \NR
+\NC use_typo_metrics             \NC number   \NC \NC \NR
+\NC weight_width_slope_only      \NC number   \NC \NC \NR
+\NC head_optimized_for_cleartype \NC number   \NC \NC \NR
+\NC uni_interp                   \NC enum     \NC \type {unset}, \type {none}, \type {adobe},
+                                                  \type {greek}, \type {japanese}, \type {trad_chinese},
+                                                  \type {simp_chinese}, \type {korean}, \type {ams}\NC \NR
+\NC origname                     \NC string   \NC the file name, as supplied by the user\NC \NR
+\NC map                          \NC table    \NC \NC \NR
+\NC private                      \NC table    \NC \NC \NR
+\NC xuid                         \NC string   \NC \NC \NR
+\NC pfminfo                      \NC table    \NC \NC \NR
+\NC names                        \NC table    \NC \NC \NR
+\NC cidinfo                      \NC table    \NC \NC \NR
+\NC subfonts                     \NC array    \NC \NC \NR
+\NC commments                    \NC string   \NC \NC \NR
+\NC fontlog                      \NC string   \NC \NC \NR
+\NC cvt_names                    \NC string   \NC \NC \NR
+\NC anchor_classes               \NC table    \NC \NC \NR
+\NC ttf_tables                   \NC table    \NC \NC \NR
+\NC ttf_tab_saved                \NC table    \NC \NC \NR
+\NC kerns                        \NC table    \NC \NC \NR
+\NC vkerns                       \NC table    \NC \NC \NR
+\NC texdata                      \NC table    \NC \NC \NR
+\NC lookups                      \NC table    \NC \NC \NR
+\NC gpos                         \NC table    \NC \NC \NR
+\NC gsub                         \NC table    \NC \NC \NR
+\NC mm                           \NC table    \NC \NC \NR
+\NC chosenname                   \NC string   \NC \NC \NR
+\NC macstyle                     \NC number   \NC \NC \NR
+\NC fondname                     \NC string   \NC \NC \NR
+%NC design_size                  \NC number   \NC \NC \NR
+\NC fontstyle_id                 \NC number   \NC \NC \NR
+\NC fontstyle_name               \NC table    \NC \NC \NR
+%NC design_range_bottom          \NC number   \NC \NC \NR
+%NC design_range_top             \NC number   \NC \NC \NR
+\NC strokewidth                  \NC float    \NC \NC \NR
+\NC mark_classes                 \NC table    \NC \NC \NR
+\NC creationtime                 \NC number   \NC \NC \NR
+\NC modificationtime             \NC number   \NC \NC \NR
+\NC os2_version                  \NC number   \NC \NC \NR
+\NC sfd_version                  \NC number   \NC \NC \NR
+\NC math                         \NC table    \NC \NC \NR
+\NC validation_state             \NC table    \NC \NC \NR
+\NC horiz_base                   \NC table    \NC \NC \NR
+\NC vert_base                    \NC table    \NC \NC \NR
+\NC extrema_bound                \NC number   \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{Glyph items}
+
+The \type {glyphs} is an array containing the per|-|character
+information (quite a few of these are only present if nonzero).
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key         \NC \bf type \NC \bf explanation \NC \NR
+\NC name              \NC string   \NC the glyph name \NC \NR
+\NC unicode           \NC number   \NC unicode code point, or -1 \NC \NR
+\NC boundingbox       \NC array    \NC array of four numbers, see note below \NC \NR
+\NC width             \NC number   \NC only for horizontal fonts \NC \NR
+\NC vwidth            \NC number   \NC only for vertical fonts \NC \NR
+\NC tsidebearing      \NC number   \NC only for vertical ttf/otf fonts, and only if nonzero \NC \NR
+\NC lsidebearing      \NC number   \NC only if nonzero and not equal to boundingbox[1] \NC \NR
+\NC class             \NC string   \NC one of "none", "base", "ligature", "mark", "component"
+                                       (if not present, the glyph class is \quote {automatic}) \NC \NR
+\NC kerns             \NC array    \NC only for horizontal fonts, if set \NC \NR
+\NC vkerns            \NC array    \NC only for vertical fonts, if set \NC \NR
+\NC dependents        \NC array    \NC linear array of glyph name strings, only if nonempty\NC \NR
+\NC lookups           \NC table    \NC only if nonempty \NC \NR
+\NC ligatures         \NC table    \NC only if nonempty \NC \NR
+\NC anchors           \NC table    \NC only if set \NC \NR
+\NC comment           \NC string   \NC only if set \NC \NR
+\NC tex_height        \NC number   \NC only if set \NC \NR
+\NC tex_depth         \NC number   \NC only if set \NC \NR
+\NC italic_correction \NC number   \NC only if set \NC \NR
+\NC top_accent        \NC number   \NC only if set \NC \NR
+\NC is_extended_shape \NC number   \NC only if this character is part of a math extension list \NC \NR
+\NC altuni            \NC table    \NC alternate \UNICODE\ items \NC \NR
+\NC vert_variants     \NC table    \NC \NC \NR
+\NC horiz_variants    \NC table    \NC \NC \NR
+\NC mathkern          \NC table    \NC \NC \NR
+\stoptabulate
+
+On \type {boundingbox}: The boundingbox information for \TRUETYPE\ fonts and
+\TRUETYPE-based \OTF\ fonts is read directly from the font file.
+\POSTSCRIPT-based fonts do not have this information, so the boundingbox of
+traditional \POSTSCRIPT\ fonts is generated by interpreting the actual bezier
+curves to find the exact boundingbox. This can be a slow process, so the
+boundingboxes of \POSTSCRIPT-based \OTF\ fonts (and raw \CFF\ fonts) are
+calculated using an approximation of the glyph shape based on the actual glyph
+points only, instead of taking the whole curve into account. This means that
+glyphs that have missing points at extrema will have a too|-|tight boundingbox,
+but the processing is so much faster that in our opinion the tradeoff is worth
+it.
+
+The \type {kerns} and \type {vkerns} are linear arrays of small hashes:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC char      \NC string   \NC \NC \NR
+\NC off       \NC number   \NC \NC \NR
+\NC lookup    \NC string   \NC \NC \NR
+\stoptabulate
+
+The \type {lookups} is a hash, based on lookup subtable names, with
+the value of each key inside that a linear array of small hashes:
+
+% TODO: fix this description
+\starttabulate[|lT|l|p|]
+\NC \ssbf key     \NC \bf type \NC \bf explanation \NC \NR
+\NC type          \NC enum     \NC \type {position}, \type {pair}, \type
+                                   {substitution}, \type {alternate}, \type
+                                   {multiple}, \type {ligature}, \type {lcaret},
+                                   \type {kerning}, \type {vkerning}, \type
+                                   {anchors}, \type {contextpos}, \type
+                                   {contextsub}, \type {chainpos}, \type
+                                   {chainsub}, \type {reversesub}, \type {max},
+                                   \type {kernback}, \type {vkernback} \NC \NR
+\NC specification \NC table    \NC extra data \NC \NR
+\stoptabulate
+
+For the first seven values of \type {type}, there can be additional
+sub|-|information, stored in the sub-table \type {specification}:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf value  \NC \bf type \NC \bf explanation \NC \NR
+\NC position     \NC table    \NC a table of the \type {offset_specs} type \NC \NR
+\NC pair         \NC table    \NC one string: \type {paired}, and an array of one
+                                  or two \type {offset_specs} tables: \type
+                                  {offsets} \NC \NR
+\NC substitution \NC table    \NC one string: \type {variant} \NC \NR
+\NC alternate    \NC table    \NC one string: \type {components} \NC \NR
+\NC multiple     \NC table    \NC one string: \type {components} \NC \NR
+\NC ligature     \NC table    \NC two strings: \type {components}, \type {char} \NC \NR
+\NC lcaret       \NC array    \NC linear array of numbers \NC \NR
+\stoptabulate
+
+Tables for \type {offset_specs} contain up to four number|-|valued fields: \type
+{x} (a horizontal offset), \type {y} (a vertical offset), \type {h} (an advance
+width correction) and \type {v} (an advance height correction).
+
+The \type {ligatures} is a linear array of small hashes:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key  \NC \bf type \NC \bf explanation \NC \NR
+\NC lig        \NC table    \NC uses the same substructure as a single item in
+                                the \type {lookups} table explained above \NC \NR
+\NC char       \NC string   \NC \NC \NR
+\NC components \NC array    \NC linear array of named components \NC \NR
+\NC ccnt       \NC number   \NC \NC \NR
+\stoptabulate
+
+The \type {anchor} table is indexed by a string signifying the anchor type, which
+is one of
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC mark      \NC table    \NC placement mark \NC \NR
+\NC basechar  \NC table    \NC mark for attaching combining items to a base char \NC \NR
+\NC baselig   \NC table    \NC mark for attaching combining items to a ligature \NC \NR
+\NC basemark  \NC table    \NC generic mark for attaching combining items to connect to \NC \NR
+\NC centry    \NC table    \NC cursive entry point \NC \NR
+\NC cexit     \NC table    \NC cursive exit point \NC \NR
+\stoptabulate
+
+The content of these is a short array of defined anchors, with the
+entry keys being the anchor names. For all except \type {baselig}, the
+value is a single table with this definition:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key    \NC \bf type \NC \bf explanation \NC \NR
+\NC x            \NC number   \NC x location \NC \NR
+\NC y            \NC number   \NC y location \NC \NR
+\NC ttf_pt_index \NC number   \NC truetype point index, only if given \NC \NR
+\stoptabulate
+
+For \type {baselig}, the value is a small array of such anchor sets sets, one for
+each constituent item of the ligature.
+
+For clarification, an anchor table could for example look like this :
+
+\starttyping
+['anchor'] = {
+    ['basemark'] = {
+        ['Anchor-7'] = { ['x']=170, ['y']=1080 }
+    },
+    ['mark'] ={
+        ['Anchor-1'] = { ['x']=160, ['y']=810 },
+        ['Anchor-4'] = { ['x']=160, ['y']=800 }
+    },
+    ['baselig'] = {
+        [1] = { ['Anchor-2'] = { ['x']=160, ['y']=650 } },
+        [2] = { ['Anchor-2'] = { ['x']=460, ['y']=640 } }
+        }
+    }
+\stoptyping
+
+Note: The \type {baselig} table can be sparse!
+
+\subsubsubsection{map table}
+
+The top|-|level map is a list of encoding mappings. Each of those is a table
+itself.
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC enccount  \NC number   \NC \NC \NR
+\NC encmax    \NC number   \NC \NC \NR
+\NC backmax   \NC number   \NC \NC \NR
+\NC remap     \NC table    \NC \NC \NR
+\NC map       \NC array    \NC non|-|linear array of mappings\NC \NR
+\NC backmap   \NC array    \NC non|-|linear array of backward mappings\NC \NR
+\NC enc       \NC table    \NC \NC \NR
+\stoptabulate
+
+The \type {remap} table is very small:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC firstenc  \NC number   \NC \NC \NR
+\NC lastenc   \NC number   \NC \NC \NR
+\NC infont    \NC number   \NC \NC \NR
+\stoptabulate
+
+The \type {enc} table is a bit more verbose:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key        \NC \bf type \NC \bf explanation \NC \NR
+\NC enc_name         \NC string   \NC \NC \NR
+\NC char_cnt         \NC number   \NC \NC \NR
+\NC char_max         \NC number   \NC \NC \NR
+\NC unicode          \NC array    \NC of \UNICODE\ position numbers\NC \NR
+\NC psnames          \NC array    \NC of \POSTSCRIPT\ glyph names\NC \NR
+\NC builtin          \NC number   \NC \NC \NR
+\NC hidden           \NC number   \NC \NC \NR
+\NC only_1byte       \NC number   \NC \NC \NR
+\NC has_1byte        \NC number   \NC \NC \NR
+\NC has_2byte        \NC number   \NC \NC \NR
+\NC is_unicodebmp    \NC number   \NC only if nonzero\NC \NR
+\NC is_unicodefull   \NC number   \NC only if nonzero\NC \NR
+\NC is_custom        \NC number   \NC only if nonzero\NC \NR
+\NC is_original      \NC number   \NC only if nonzero\NC \NR
+\NC is_compact       \NC number   \NC only if nonzero\NC \NR
+\NC is_japanese      \NC number   \NC only if nonzero\NC \NR
+\NC is_korean        \NC number   \NC only if nonzero\NC \NR
+\NC is_tradchinese   \NC number   \NC only if nonzero [name?]\NC \NR
+\NC is_simplechinese \NC number   \NC only if nonzero\NC \NR
+\NC low_page         \NC number   \NC \NC \NR
+\NC high_page        \NC number   \NC \NC \NR
+\NC iconv_name       \NC string   \NC \NC \NR
+\NC iso_2022_escape  \NC string   \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{private table}
+
+This is the font's private \POSTSCRIPT\ dictionary, if any. Keys and values are
+both strings.
+
+\subsubsubsection{cidinfo table}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key  \NC \bf type \NC \bf explanation \NC \NR
+\NC registry   \NC string   \NC \NC \NR
+\NC ordering   \NC string   \NC \NC \NR
+\NC supplement \NC number   \NC \NC \NR
+\NC version    \NC number   \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection[fontloaderpfminfotable]{pfminfo table}
+
+The \type {pfminfo} table contains most of the OS/2 information:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key        \NC \bf type \NC \bf explanation \NC \NR
+\NC pfmset           \NC number   \NC \NC \NR
+\NC winascent_add    \NC number   \NC \NC \NR
+\NC windescent_add   \NC number   \NC \NC \NR
+\NC hheadascent_add  \NC number   \NC \NC \NR
+\NC hheaddescent_add \NC number   \NC \NC \NR
+\NC typoascent_add   \NC number   \NC \NC \NR
+\NC typodescent_add  \NC number   \NC \NC \NR
+\NC subsuper_set     \NC number   \NC \NC \NR
+\NC panose_set       \NC number   \NC \NC \NR
+\NC hheadset         \NC number   \NC \NC \NR
+\NC vheadset         \NC number   \NC \NC \NR
+\NC pfmfamily        \NC number   \NC \NC \NR
+\NC weight           \NC number   \NC \NC \NR
+\NC width            \NC number   \NC \NC \NR
+\NC avgwidth         \NC number   \NC \NC \NR
+\NC firstchar        \NC number   \NC \NC \NR
+\NC lastchar         \NC number   \NC \NC \NR
+\NC fstype           \NC number   \NC \NC \NR
+\NC linegap          \NC number   \NC \NC \NR
+\NC vlinegap         \NC number   \NC \NC \NR
+\NC hhead_ascent     \NC number   \NC \NC \NR
+\NC hhead_descent    \NC number   \NC \NC \NR
+\NC os2_typoascent   \NC number   \NC \NC \NR
+\NC os2_typodescent  \NC number   \NC \NC \NR
+\NC os2_typolinegap  \NC number   \NC \NC \NR
+\NC os2_winascent    \NC number   \NC \NC \NR
+\NC os2_windescent   \NC number   \NC \NC \NR
+\NC os2_subxsize     \NC number   \NC \NC \NR
+\NC os2_subysize     \NC number   \NC \NC \NR
+\NC os2_subxoff      \NC number   \NC \NC \NR
+\NC os2_subyoff      \NC number   \NC \NC \NR
+\NC os2_supxsize     \NC number   \NC \NC \NR
+\NC os2_supysize     \NC number   \NC \NC \NR
+\NC os2_supxoff      \NC number   \NC \NC \NR
+\NC os2_supyoff      \NC number   \NC \NC \NR
+\NC os2_strikeysize  \NC number   \NC \NC \NR
+\NC os2_strikeypos   \NC number   \NC \NC \NR
+\NC os2_family_class \NC number   \NC \NC \NR
+\NC os2_xheight      \NC number   \NC \NC \NR
+\NC os2_capheight    \NC number   \NC \NC \NR
+\NC os2_defaultchar  \NC number   \NC \NC \NR
+\NC os2_breakchar    \NC number   \NC \NC \NR
+\NC os2_vendor       \NC string   \NC \NC \NR
+\NC codepages        \NC table    \NC A two-number array of encoded code pages\NC \NR
+\NC unicoderages     \NC table    \NC A four-number array of encoded unicode ranges\NC \NR
+\NC panose           \NC table    \NC \NC \NR
+\stoptabulate
+
+The \type {panose} subtable has exactly 10 string keys:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key       \NC \bf type \NC \bf explanation \NC \NR
+\NC familytype      \NC string   \NC Values as in the \OPENTYPE\ font
+                                     specification: \type {Any}, \type {No Fit},
+                                     \type {Text and Display}, \type {Script},
+                                     \type {Decorative}, \type {Pictorial} \NC
+                                     \NR
+\NC serifstyle      \NC string   \NC See the \OPENTYPE\ font specification for
+                                     values \NC \NR
+\NC weight          \NC string   \NC id. \NC \NR
+\NC proportion      \NC string   \NC id. \NC \NR
+\NC contrast        \NC string   \NC id. \NC \NR
+\NC strokevariation \NC string   \NC id. \NC \NR
+\NC armstyle        \NC string   \NC id. \NC \NR
+\NC letterform      \NC string   \NC id. \NC \NR
+\NC midline         \NC string   \NC id. \NC \NR
+\NC xheight         \NC string   \NC id. \NC \NR
+\stoptabulate
+
+\subsubsubsection[fontloadernamestable]{names table}
+
+Each item has two top|-|level keys:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC lang      \NC string   \NC language for this entry \NC \NR
+\NC names     \NC table    \NC \NC \NR
+\stoptabulate
+
+The \type {names} keys are the actual \TRUETYPE\ name strings. The possible keys
+are:
+
+\starttabulate[|lT|p|]
+\NC \ssbf key       \NC \bf explanation \NC \NR
+\NC copyright       \NC \NC \NR
+\NC family          \NC \NC \NR
+\NC subfamily       \NC \NC \NR
+\NC uniqueid        \NC \NC \NR
+\NC fullname        \NC \NC \NR
+\NC version         \NC \NC \NR
+\NC postscriptname  \NC \NC \NR
+\NC trademark       \NC \NC \NR
+\NC manufacturer    \NC \NC \NR
+\NC designer        \NC \NC \NR
+\NC descriptor      \NC \NC \NR
+\NC venderurl       \NC \NC \NR
+\NC designerurl     \NC \NC \NR
+\NC license         \NC \NC \NR
+\NC licenseurl      \NC \NC \NR
+\NC idontknow       \NC \NC \NR
+\NC preffamilyname  \NC \NC \NR
+\NC prefmodifiers   \NC \NC \NR
+\NC compatfull      \NC \NC \NR
+\NC sampletext      \NC \NC \NR
+\NC cidfindfontname \NC \NC \NR
+\NC wwsfamily       \NC \NC \NR
+\NC wwssubfamily    \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{anchor_classes table}
+
+The anchor_classes classes:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC name      \NC string   \NC a descriptive id of this anchor class\NC \NR
+\NC lookup    \NC string   \NC \NC \NR
+\NC type      \NC string   \NC one of \type {mark}, \type {mkmk}, \type {curs}, \type {mklg} \NC \NR
+\stoptabulate
+
+% type is actually a lookup subtype, not a feature name. Officially, these
+% strings should be gpos_mark2mark etc.
+
+\subsubsubsection{gpos table}
+
+The \type {gpos} table has one array entry for each lookup. (The \type {gpos_}
+prefix is somewhat redundant.)
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC type      \NC string   \NC one of \type {gpos_single}, \type {gpos_pair},
+                               \type {gpos_cursive}, \type {gpos_mark2base},\crlf
+                               \type {gpos_mark2ligature}, \type
+                               {gpos_mark2mark}, \type {gpos_context},\crlf \type
+                               {gpos_contextchain} \NC \NR
+\NC flags     \NC table    \NC \NC \NR
+\NC name      \NC string   \NC \NC \NR
+\NC features  \NC array    \NC \NC \NR
+\NC subtables \NC array    \NC \NC \NR
+\stoptabulate
+
+The flags table has a true value for each of the lookup flags that is actually
+set:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key            \NC \bf type \NC \bf explanation \NC \NR
+\NC r2l                  \NC boolean  \NC \NC \NR
+\NC ignorebaseglyphs     \NC boolean  \NC \NC \NR
+\NC ignoreligatures      \NC boolean  \NC \NC \NR
+\NC ignorecombiningmarks \NC boolean  \NC \NC \NR
+\NC mark_class           \NC string   \NC \NC \NR
+\stoptabulate
+
+The features subtable items of gpos have:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC tag       \NC string   \NC \NC \NR
+\NC scripts   \NC table    \NC \NC \NR
+\stoptabulate
+
+The scripts table within features has:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type         \NC \bf explanation \NC \NR
+\NC script    \NC string           \NC \NC \NR
+\NC langs     \NC array of strings \NC \NC \NR
+\stoptabulate
+
+The subtables table has:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key        \NC \bf type \NC \bf explanation \NC \NR
+\NC name             \NC string   \NC \NC \NR
+\NC suffix           \NC string   \NC (only if used)\NC \NR % used by gpos_single to get a default
+\NC anchor_classes   \NC number   \NC (only if used)\NC \NR
+\NC vertical_kerning \NC number   \NC (only if used)\NC \NR
+\NC kernclass        \NC table    \NC (only if used)\NC \NR
+\stoptabulate
+
+
+The kernclass with subtables table has:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC firsts    \NC array of strings  \NC \NC \NR
+\NC seconds   \NC array of strings   \NC \NC \NR
+\NC lookup    \NC string or array \NC associated lookup(s) \NC \NR
+\NC offsets   \NC array of numbers  \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{gsub table}
+
+This has identical layout to the \type {gpos} table, except for the
+type:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC type      \NC string   \NC one of \type {gsub_single}, \type {gsub_multiple},
+                               \type {gsub_alternate}, \type
+                               {gsub_ligature},\crlf \type {gsub_context}, \type
+                               {gsub_contextchain}, \type
+                               {gsub_reversecontextchain} \NC \NR
+\stoptabulate
+
+\subsubsubsection{ttf_tables and ttf_tab_saved tables}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC tag       \NC string   \NC \NC \NR
+\NC len       \NC number   \NC \NC \NR
+\NC maxlen    \NC number   \NC \NC \NR
+\NC data      \NC number   \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{mm table}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key      \NC \bf type \NC \bf explanation \NC \NR
+\NC axes           \NC table    \NC array of axis names \NC \NR
+\NC instance_count \NC number   \NC \NC \NR
+\NC positions      \NC table    \NC array of instance positions
+                                    (\#axes * instances )\NC \NR
+\NC defweights     \NC table    \NC array of default weights for instances \NC \NR
+\NC cdv            \NC string   \NC \NC \NR
+\NC ndv            \NC string   \NC \NC \NR
+\NC axismaps       \NC table    \NC \NC \NR
+\stoptabulate
+
+The \type {axismaps}:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key            \NC \bf type \NC \bf explanation \NC \NR
+\NC blends               \NC table     \NC an array of blend points \NC \NR
+\NC designs              \NC table     \NC an array of design values \NC \NR
+\NC min                  \NC number   \NC \NC \NR
+\NC def                  \NC number   \NC \NC \NR
+\NC max                  \NC number   \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{mark_classes table}
+
+The keys in this table are mark class names, and the values are a
+space|-|separated string of glyph names in this class.
+
+\subsubsubsection{math table}
+
+\starttabulate[|lT|p|]
+\NC ScriptPercentScaleDown                   \NC \NC \NR
+\NC ScriptScriptPercentScaleDown             \NC \NC \NR
+\NC DelimitedSubFormulaMinHeight             \NC \NC \NR
+\NC DisplayOperatorMinHeight                 \NC \NC \NR
+\NC MathLeading                              \NC \NC \NR
+\NC AxisHeight                               \NC \NC \NR
+\NC AccentBaseHeight                         \NC \NC \NR
+\NC FlattenedAccentBaseHeight                \NC \NC \NR
+\NC SubscriptShiftDown                       \NC \NC \NR
+\NC SubscriptTopMax                          \NC \NC \NR
+\NC SubscriptBaselineDropMin                 \NC \NC \NR
+\NC SuperscriptShiftUp                       \NC \NC \NR
+\NC SuperscriptShiftUpCramped                \NC \NC \NR
+\NC SuperscriptBottomMin                     \NC \NC \NR
+\NC SuperscriptBaselineDropMax               \NC \NC \NR
+\NC SubSuperscriptGapMin                     \NC \NC \NR
+\NC SuperscriptBottomMaxWithSubscript        \NC \NC \NR
+\NC SpaceAfterScript                         \NC \NC \NR
+\NC UpperLimitGapMin                         \NC \NC \NR
+\NC UpperLimitBaselineRiseMin                \NC \NC \NR
+\NC LowerLimitGapMin                         \NC \NC \NR
+\NC LowerLimitBaselineDropMin                \NC \NC \NR
+\NC StackTopShiftUp                          \NC \NC \NR
+\NC StackTopDisplayStyleShiftUp              \NC \NC \NR
+\NC StackBottomShiftDown                     \NC \NC \NR
+\NC StackBottomDisplayStyleShiftDown         \NC \NC \NR
+\NC StackGapMin                              \NC \NC \NR
+\NC StackDisplayStyleGapMin                  \NC \NC \NR
+\NC StretchStackTopShiftUp                   \NC \NC \NR
+\NC StretchStackBottomShiftDown              \NC \NC \NR
+\NC StretchStackGapAboveMin                  \NC \NC \NR
+\NC StretchStackGapBelowMin                  \NC \NC \NR
+\NC FractionNumeratorShiftUp                 \NC \NC \NR
+\NC FractionNumeratorDisplayStyleShiftUp     \NC \NC \NR
+\NC FractionDenominatorShiftDown             \NC \NC \NR
+\NC FractionDenominatorDisplayStyleShiftDown \NC \NC \NR
+\NC FractionNumeratorGapMin                  \NC \NC \NR
+\NC FractionNumeratorDisplayStyleGapMin      \NC \NC \NR
+\NC FractionRuleThickness                    \NC \NC \NR
+\NC FractionDenominatorGapMin                \NC \NC \NR
+\NC FractionDenominatorDisplayStyleGapMin    \NC \NC \NR
+\NC SkewedFractionHorizontalGap              \NC \NC \NR
+\NC SkewedFractionVerticalGap                \NC \NC \NR
+\NC OverbarVerticalGap                       \NC \NC \NR
+\NC OverbarRuleThickness                     \NC \NC \NR
+\NC OverbarExtraAscender                     \NC \NC \NR
+\NC UnderbarVerticalGap                      \NC \NC \NR
+\NC UnderbarRuleThickness                    \NC \NC \NR
+\NC UnderbarExtraDescender                   \NC \NC \NR
+\NC RadicalVerticalGap                       \NC \NC \NR
+\NC RadicalDisplayStyleVerticalGap           \NC \NC \NR
+\NC RadicalRuleThickness                     \NC \NC \NR
+\NC RadicalExtraAscender                     \NC \NC \NR
+\NC RadicalKernBeforeDegree                  \NC \NC \NR
+\NC RadicalKernAfterDegree                   \NC \NC \NR
+\NC RadicalDegreeBottomRaisePercent          \NC \NC \NR
+\NC MinConnectorOverlap                      \NC \NC \NR
+\NC FractionDelimiterSize                    \NC \NC \NR
+\NC FractionDelimiterDisplayStyleSize        \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{validation_state table}
+
+\starttabulate[|lT|p|]
+\NC \ssbf key         \NC \bf explanation \NC \NR
+\NC bad_ps_fontname   \NC \NC \NR
+\NC bad_glyph_table   \NC \NC \NR
+\NC bad_cff_table     \NC \NC \NR
+\NC bad_metrics_table \NC \NC \NR
+\NC bad_cmap_table    \NC \NC \NR
+\NC bad_bitmaps_table \NC \NC \NR
+\NC bad_gx_table      \NC \NC \NR
+\NC bad_ot_table      \NC \NC \NR
+\NC bad_os2_version   \NC \NC \NR
+\NC bad_sfnt_header   \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{horiz_base and vert_base table}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC tags      \NC table    \NC an array of script list tags\NC \NR
+\NC scripts   \NC table    \NC \NC \NR
+\stoptabulate
+
+The \type {scripts} subtable:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key        \NC \bf type \NC \bf explanation \NC \NR
+\NC baseline         \NC table   \NC \NC \NR
+\NC default_baseline \NC number  \NC \NC \NR
+\NC lang             \NC table   \NC \NC \NR
+\stoptabulate
+
+
+The \type {lang} subtable:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC tag       \NC string   \NC a script tag \NC \NR
+\NC ascent    \NC number   \NC \NC \NR
+\NC descent   \NC number   \NC \NC \NR
+\NC features  \NC table    \NC \NC \NR
+\stoptabulate
+
+The \type {features} points to an array of tables with the same layout except
+that in those nested tables, the tag represents a language.
+
+\subsubsubsection{altuni table}
+
+An array of alternate \UNICODE\ values. Inside that array are hashes with:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC unicode   \NC number   \NC this glyph is also used for this unicode \NC \NR
+\NC variant   \NC number   \NC the alternative is driven by this unicode selector \NC \NR
+\stoptabulate
+
+\subsubsubsection{vert_variants and horiz_variants table}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key         \NC \bf type \NC \bf explanation \NC \NR
+\NC variants          \NC string   \NC \NC \NR
+\NC italic_correction \NC number   \NC \NC \NR
+\NC parts             \NC table    \NC \NC \NR
+\stoptabulate
+
+The \type {parts} table is an array of smaller tables:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC component \NC string   \NC \NC \NR
+\NC extender  \NC number   \NC \NC \NR
+\NC start     \NC number   \NC \NC \NR
+\NC end       \NC number   \NC \NC \NR
+\NC advance   \NC number   \NC \NC \NR
+\stoptabulate
+
+
+\subsubsubsection{mathkern table}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key    \NC \bf type \NC \bf explanation \NC \NR
+\NC top_right    \NC table    \NC \NC \NR
+\NC bottom_right \NC table    \NC \NC \NR
+\NC top_left     \NC table    \NC \NC \NR
+\NC bottom_left  \NC table    \NC \NC \NR
+\stoptabulate
+
+Each of the subtables is an array of small hashes with two keys:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC height    \NC number   \NC \NC \NR
+\NC kern      \NC number   \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{kerns table}
+
+Substructure is identical to the per|-|glyph subtable.
+
+\subsubsubsection{vkerns table}
+
+Substructure is identical to the per|-|glyph subtable.
+
+\subsubsubsection{texdata table}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC type      \NC string   \NC \type {unset}, \type {text}, \type {math}, \type {mathext} \NC \NR
+\NC params    \NC array    \NC 22 font numeric parameters \NC \NR
+\stoptabulate
+
+\subsubsubsection{lookups table}
+
+Top|-|level \type {lookups} is quite different from the ones at character level.
+The keys in this hash are strings, the values the actual lookups, represented as
+dictionary tables.
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key     \NC \bf type \NC \bf explanation \NC \NR
+\NC type          \NC string   \NC \NC \NR
+\NC format        \NC enum     \NC one of \type {glyphs}, \type {class}, \type {coverage}, \type {reversecoverage} \NC \NR
+\NC tag           \NC string   \NC \NC \NR
+\NC current_class \NC array    \NC \NC \NR
+\NC before_class  \NC array    \NC \NC \NR
+\NC after_class   \NC array    \NC \NC \NR
+\NC rules         \NC array    \NC an array of rule items\NC \NR
+\stoptabulate
+
+Rule items have one common item and one specialized item:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key       \NC \bf type \NC \bf explanation \NC \NR
+\NC lookups         \NC array    \NC a linear array of lookup names\NC \NR
+\NC glyphs          \NC array    \NC only if the parent's format is \type {glyphs}\NC \NR
+\NC class           \NC array    \NC only if the parent's format is \type {class}\NC \NR
+\NC coverage        \NC array    \NC only if the parent's format is \type {coverage}\NC \NR
+\NC reversecoverage \NC array    \NC only if the parent's format is \type {reversecoverage}\NC \NR
+\stoptabulate
+
+A glyph table is:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC names     \NC string   \NC \NC \NR
+\NC back      \NC string   \NC \NC \NR
+\NC fore      \NC string   \NC \NC \NR
+\stoptabulate
+
+A class table is:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC current   \NC array    \NC of numbers \NC \NR
+\NC before    \NC array    \NC of numbers  \NC \NR
+\NC after     \NC array    \NC of numbers  \NC \NR
+\stoptabulate
+
+coverage:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key \NC \bf type \NC \bf explanation \NC \NR
+\NC current   \NC array    \NC of strings \NC \NR
+\NC before    \NC array    \NC of strings\NC \NR
+\NC after     \NC array    \NC of strings \NC \NR
+\stoptabulate
+
+reversecoverage:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key    \NC \bf type \NC \bf explanation \NC \NR
+\NC current      \NC array    \NC of strings \NC \NR
+\NC before       \NC array    \NC of strings\NC \NR
+\NC after        \NC array    \NC of strings \NC \NR
+\NC replacements \NC string   \NC \NC \NR
+\stoptabulate
+
+%***********************************************************************
+
+\section{The \type {img} library}
+
+The \type {img} library can be used as an alternative to \type {\pdfximage} and
+\type {\pdfrefximage}, and the associated \quote {satellite} commands like \type
+{\pdfximagebbox}. Image objects can also be used within virtual fonts via the
+\type {image} command listed in~\in {section} [virtualfonts].
+
+\subsection{\type {img.new}}
+
+\startfunctioncall
+<image> var = img.new()
+<image> var = img.new(<table> image_spec)
+\stopfunctioncall
+
+This function creates a userdata object of type \quote {image}. The \type
+{image_spec} argument is optional. If it is given, it must be a table, and that
+table must contain a \type {filename} key. A number of other keys can also be
+useful, these are explained below.
+
+You can either say
+
+\starttyping
+a = img.new()
+\stoptyping
+
+followed by
+
+\starttyping
+a.filename = "foo.png"
+\stoptyping
+
+or you can put the file name (and some or all of the other keys) into a table
+directly, like so:
+
+\starttyping
+a = img.new({filename='foo.pdf', page=1})
+\stoptyping
+
+The generated \type {<image>} userdata object allows access to a set of
+user|-|specified values as well as a set of values that are normally filled in
+and updated automatically by \LUATEX\ itself. Some of those are derived from the
+actual image file, others are updated to reflect the \PDF\ output status of the
+object.
+
+There is one required user-specified field: the file name (\type {filename}). It
+can optionally be augmented by the requested image dimensions (\type {width},
+\type {depth}, \type {height}), user|-|specified image attributes (\type {attr}),
+the requested \PDF\ page identifier (\type {page}), the requested boundingbox
+(\type {pagebox}) for \PDF\ inclusion, the requested color space object (\type
+{colorspace}).
+
+The function \type {img.new} does not access the actual image file, it just
+creates the \type {<image>} userdata object and initializes some memory
+structures. The \type {<image>} object and its internal structures are
+automatically garbage collected.
+
+Once the image is scanned, all the values in the \type {<image>} except \type
+{width}, \type {height} and \type {depth}, become frozen, and you cannot change
+them any more.
+
+\subsection{\type {img.keys}}
+
+\startfunctioncall
+<table> keys = img.keys()
+\stopfunctioncall
+
+This function returns a list of all the possible \type {image_spec} keys, both
+user-supplied and automatic ones.
+
+% hahe: i need to add r/w ro column...
+\starttabulate[|l|l|p|]
+\NC \bf field name\NC \bf type \NC description \NC \NR
+\NC attr          \NC string   \NC the image attributes for \LUATEX \NC \NR
+\NC bbox          \NC table    \NC table with 4 boundingbox dimensions
+                                   \type {llx}, \type {lly}, \type {urx},
+                                   and \type {ury} overruling the \type {pagebox}
+                                   entry\NC \NR
+\NC colordepth    \NC number   \NC the number of bits used by the color space\NC \NR
+\NC colorspace    \NC number   \NC the color space object number \NC \NR
+\NC depth         \NC number   \NC the image depth for \LUATEX\
+                                   (in scaled points)\NC \NR
+\NC filename      \NC string   \NC the image file name \NC \NR
+\NC filepath      \NC string   \NC the full (expanded) file name of the image\NC \NR
+\NC height        \NC number   \NC the image height for \LUATEX\
+                                   (in scaled points)\NC \NR
+\NC imagetype     \NC string   \NC one of \type {pdf}, \type {png}, \type {jpg}, \type {jp2},
+                                   \type {jbig2}, or \type {nil} \NC \NR
+\NC index         \NC number   \NC the \PDF\ image name suffix \NC \NR
+\NC objnum        \NC number   \NC the \PDF\ image object number \NC \NR
+\NC page          \NC ??       \NC the identifier for the requested image page
+                                   (type is number or string,
+                                   default is the number 1)\NC \NR
+\NC pagebox       \NC string   \NC the requested bounding box, one of
+                                   \type {none}, \type {media}, \type {crop},
+                                   \type {bleed}, \type {trim}, \type {art} \NC \NR
+\NC pages         \NC number   \NC the total number of available pages \NC \NR
+\NC rotation      \NC number   \NC the image rotation from included \PDF\ file,
+                                   in multiples of 90~deg. \NC \NR
+\NC stream        \NC string   \NC the raw stream data for an \type {/Xobject}
+                                   \type {/Form} object\NC \NR
+\NC transform     \NC number   \NC the image transform, integer number 0..7\NC \NR
+\NC width         \NC number   \NC the image width for \LUATEX\
+                                   (in scaled points)\NC \NR
+\NC xres          \NC number   \NC the horizontal natural image resolution
+                                   (in \DPI) \NC \NR
+\NC xsize         \NC number   \NC the natural image width \NC \NR
+\NC yres          \NC number   \NC the vertical natural image resolution
+                                   (in \DPI) \NC \NR
+\NC ysize         \NC number   \NC the natural image height \NC \NR
+\stoptabulate
+
+A running (undefined) dimension in \type {width}, \type {height}, or \type
+{depth} is represented as \type {nil} in \LUA, so if you want to load an image at
+its \quote {natural} size, you do not have to specify any of those three fields.
+
+The \type {stream} parameter allows to fabricate an \type {/XObject} \type
+{/Form} object from a string giving the stream contents, e.g., for a filled
+rectangle:
+
+\startfunctioncall
+a.stream = "0 0 20 10 re f"
+\stopfunctioncall
+
+When writing the image, an \type {/Xobject} \type {/Form} object is created, like
+with embedded \PDF\ file writing. The object is written out only once. The \type
+{stream} key requires that also the \type {bbox} table is given. The \type
+{stream} key conflicts with the \type {filename} key. The \type {transform} key
+works as usual also with \type {stream}.
+
+The \type {bbox} key needs a table with four boundingbox values, e.g.:
+
+\startfunctioncall
+a.bbox = {"30bp", 0, "225bp", "200bp"}
+\stopfunctioncall
+
+This replaces and overrules any given \type {pagebox} value; with given \type
+{bbox} the box dimensions coming with an embedded \PDF\ file are ignored. The
+\type {xsize} and \type {ysize} dimensions are set accordingly, when the image is
+scaled. The \type {bbox} parameter is ignored for non-\PDF\ images.
+
+The \type {transform} allows to mirror and rotate the image in steps of 90~deg.
+The default value~$0$ gives an unmirrored, unrotated image. Values $1-3$ give
+counterclockwise rotation by $90$, $180$, or $270$~degrees, whereas with values
+$4-7$ the image is first mirrored and then rotated counterclockwise by $90$,
+$180$, or $270$~degrees. The \type {transform} operation gives the same visual
+result as if you would externally preprocess the image by a graphics tool and
+then use it by \LUATEX. If a \PDF\ file to be embedded already contains a \type
+{/Rotate} specification, the rotation result is the combination of the \type
+{/Rotate} rotation followed by the \type {transform} operation.
+
+\subsection{\type {img.scan}}
+
+\startfunctioncall
+<image> var = img.scan(<image> var)
+<image> var = img.scan(<table> image_spec)
+\stopfunctioncall
+
+When you say \type {img.scan(a)} for a new image, the file is scanned, and
+variables such as \type {xsize}, \type {ysize}, image \type {type}, number of
+\type {pages}, and the resolution are extracted. Each of the \type {width}, \type
+{height}, \type {depth} fields are set up according to the image dimensions, if
+they were not given an explicit value already. An image file will never be
+scanned more than once for a given image variable. With all subsequent \type
+{img.scan(a)} calls only the dimensions are again set up (if they have been
+changed by the user in the meantime).
+
+For ease of use, you can do right-away a
+
+\starttyping
+<image> a = img.scan ({ filename = "foo.png" })
+\stoptyping
+
+without a prior \type {img.new}.
+
+Nothing is written yet at this point, so you can do \type {a=img.scan}, retrieve
+the available info like image width and height, and then throw away \type {a}
+again by saying \type {a=nil}. In that case no image object will be reserved in
+the PDF, and the used memory will be cleaned up automatically.
+
+\subsection{\type {img.copy}}
+
+\startfunctioncall
+<image> var = img.copy(<image> var)
+<image> var = img.copy(<table> image_spec)
+\stopfunctioncall
+
+If you say \type {a = b}, then both variables point to the same \type {<image>}
+object. if you want to write out an image with different sizes, you can do a
+\type {b=img.copy(a)}.
+
+Afterwards, \type {a} and \type {b} still reference the same actual image
+dictionary, but the dimensions for \type {b} can now be changed from their
+initial values that were just copies from \type {a}.
+
+\subsection{\type {img.write}}
+
+\startfunctioncall
+<image> var = img.write(<image> var)
+<image> var = img.write(<table> image_spec)
+\stopfunctioncall
+
+By \type {img.write(a)} a \PDF\ object number is allocated, and a whatsit node of
+subtype \type {pdf_refximage} is generated and put into the output list. By this
+the image \type {a} is placed into the page stream, and the image file is written
+out into an image stream object after the shipping of the current page is
+finished.
+
+Again you can do a terse call like
+
+\starttyping
+img.write ({ filename = "foo.png" })
+\stoptyping
+
+The \type {<image>} variable is returned in case you want it for later
+processing.
+
+\subsection{\type {img.immediatewrite}}
+
+\startfunctioncall
+<image> var = img.immediatewrite(<image> var)
+<image> var = img.immediatewrite(<table> image_spec)
+\stopfunctioncall
+
+By \type {img.immediatewrite(a)} a \PDF\ object number is allocated, and the
+image file for image \type {a} is written out immediately into the \PDF\ file as
+an image stream object (like with \type {\immediate}\type {\pdfximage}). The object
+number of the image stream dictionary is then available by the \type {objnum}
+key. No \type {pdf_refximage} whatsit node is generated. You will need an
+\type {img.write(a)} or \type {img.node(a)} call to let the image appear on the
+page, or reference it by another trick; else you will have a dangling image
+object in the \PDF\ file.
+
+Also here you can do a terse call like
+
+\starttyping
+a = img.immediatewrite ({ filename = "foo.png" })
+\stoptyping
+
+The \type {<image>} variable is returned and you will most likely need it.
+
+\subsection{\type {img.node}}
+
+\startfunctioncall
+<node> n = img.node(<image> var)
+<node> n = img.node(<table> image_spec)
+\stopfunctioncall
+
+This function allocates a \PDF\ object number and returns a whatsit node of
+subtype \type {pdf_refximage}, filled with the image parameters \type {width},
+\type {height}, \type {depth}, and \type {objnum}. Also here you can do a terse
+call like:
+
+\starttyping
+n = img.node ({ filename = "foo.png" })
+\stoptyping
+
+This example outputs an image:
+
+\starttyping
+node.write(img.node{filename="foo.png"})
+\stoptyping
+
+\subsection{\type {img.types}}
+
+\startfunctioncall
+<table> types = img.types()
+\stopfunctioncall
+
+This function returns a list with the supported image file type names, currently
+these are \type {pdf}, \type {png}, \type {jpg}, \type {jp2} (JPEG~2000), and
+\type {jbig2}.
+
+\subsection{\type {img.boxes}}
+
+\startfunctioncall
+<table> boxes = img.boxes()
+\stopfunctioncall
+
+This function returns a list with the supported \PDF\ page box names, currently
+these are \type {media}, \type {crop}, \type {bleed}, \type {trim}, and \type
+{art} (all in lowercase letters).
+
+%***********************************************************************
+
+\section{The \type {kpse} library}
+
+This library provides two separate, but nearly identical interfaces to the
+\KPATHSEA\ file search functionality: there is a \quote {normal} procedural
+interface that shares its kpathsea instance with \LUATEX\ itself, and an object
+oriented interface that is completely on its own.
+
+\subsection{\type {kpse.set_program_name} and \type {kpse.new}}
+
+Before the search library can be used at all, its database has to be initialized.
+There are three possibilities, two of which belong to the procedural interface.
+
+First, when \LUATEX\ is used to typeset documents, this initialization happens
+automatically and the \KPATHSEA\ executable and program names are set to \type
+{luatex} (that is, unless explicitly prohibited by the user's startup script.
+See~\in {section} [init] for more details).
+
+Second, in \TEXLUA\ mode, the initialization has to be done explicitly via the
+\type {kpse.set_program_name} function, which sets the \KPATHSEA\ executable
+(and optionally program) name.
+
+\startfunctioncall
+kpse.set_program_name(<string> name)
+kpse.set_program_name(<string> name, <string> progname)
+\stopfunctioncall
+
+The second argument controls the use of the \quote {dotted} values in the \type
+{texmf.cnf} configuration file, and defaults to the first argument.
+
+Third, if you prefer the object oriented interface, you have to call a different
+function. It has the same arguments, but it returns a userdata variable.
+
+\startfunctioncall
+local kpathsea = kpse.new(<string> name)
+local kpathsea = kpse.new(<string> name, <string> progname)
+\stopfunctioncall
+
+Apart from these two functions, the calling conventions of the interfaces are
+identical. Depending on the chosen interface, you either call \type
+{kpse.find_file()} or \type {kpathsea:find_file()}, with identical arguments and
+return vales.
+
+\subsection{\type {find_file}}
+
+The most often used function in the library is find_file:
+
+\startfunctioncall
+<string> f = kpse.find_file(<string> filename)
+<string> f = kpse.find_file(<string> filename, <string> ftype)
+<string> f = kpse.find_file(<string> filename, <boolean> mustexist)
+<string> f = kpse.find_file(<string> filename, <string> ftype, <boolean> mustexist)
+<string> f = kpse.find_file(<string> filename, <string> ftype, <number> dpi)
+\stopfunctioncall
+
+Arguments:
+\startitemize[intro]
+
+\sym{filename}
+
+the name of the file you want to find, with or without extension.
+
+\sym{ftype}
+
+maps to the \type {-format} argument of \KPSEWHICH. The supported \type {ftype}
+values are the same as the ones supported by the standalone \type {kpsewhich}
+program:
+
+\startsimplecolumns
+\starttyping
+gf
+pk
+bitmap font
+tfm
+afm
+base
+bib
+bst
+cnf
+ls-R
+fmt
+map
+mem
+mf
+mfpool
+mft
+mp
+mppool
+MetaPost support
+ocp
+ofm
+opl
+otp
+ovf
+ovp
+graphic/figure
+tex
+TeX system documentation
+texpool
+TeX system sources
+PostScript header
+Troff fonts
+type1 fonts
+vf
+dvips config
+ist
+truetype fonts
+type42 fonts
+web2c files
+other text files
+other binary files
+misc fonts
+web
+cweb
+enc files
+cmap files
+subfont definition files
+opentype fonts
+pdftex config
+lig files
+texmfscripts
+lua
+font feature files
+cid maps
+mlbib
+mlbst
+clua
+\stoptyping
+\stopsimplecolumns
+
+The default type is \type {tex}. Note: this is different from \KPSEWHICH, which
+tries to deduce the file type itself from looking at the supplied extension.
+
+\sym{mustexist}
+
+is similar to \KPSEWHICH's \type {-must-exist}, and the default is \type {false}.
+If you specify \type {true} (or a non|-|zero integer), then the \KPSE\ library
+will search the disk as well as the \type {ls-R} databases.
+
+\sym{dpi}
+
+This is used for the size argument of the formats \type {pk}, \type {gf}, and
+\type {bitmap font}. \stopitemize
+
+
+\subsection{\type {lookup}}
+
+A more powerful (but slower) generic method for finding files is also available.
+It returns a string for each found file.
+
+\startfunctioncall
+<string> f, ... = kpse.lookup(<string> filename, <table> options)
+\stopfunctioncall
+
+The options match commandline arguments from \type {kpsewhich}:
+
+\starttabulate[|l|l|p|]
+\NC \ssbf key \NC \ssbf type \NC \ssbf description \NC \NR
+\NC debug     \NC number     \NC set debugging flags for this lookup\NC     \NR
+\NC format    \NC string     \NC use specific file type (see list above)\NC \NR
+\NC dpi       \NC number     \NC use this resolution for this lookup; default 600\NC \NR
+\NC path      \NC string     \NC search in the given path\NC \NR
+\NC all       \NC boolean    \NC output all matches, not just the first\NC \NR
+\NC mustexist \NC boolean    \NC search the disk as well as ls-R if necessary\NC \NR
+\NC mktexpk   \NC boolean    \NC disable/enable mktexpk generation for this lookup\NC \NR
+\NC mktextex  \NC boolean    \NC disable/enable mktextex generation for this lookup\NC \NR
+\NC mktexmf   \NC boolean    \NC disable/enable mktexmf generation for this lookup\NC \NR
+\NC mktextfm  \NC boolean    \NC disable/enable mktextfm generation for this lookup\NC \NR
+\NC subdir    \NC string
+                  or table   \NC only output matches whose directory part
+                                 ends with the given string(s) \NC \NR
+\stoptabulate
+
+\subsection{\type {init_prog}}
+
+Extra initialization for programs that need to generate bitmap fonts.
+
+\startfunctioncall
+kpse.init_prog(<string> prefix, <number> base_dpi, <string> mfmode)
+kpse.init_prog(<string> prefix, <number> base_dpi, <string> mfmode, <string> fallback)
+\stopfunctioncall
+
+\subsection{\type {readable_file}}
+
+Test if an (absolute) file name is a readable file.
+
+\startfunctioncall
+<string> f = kpse.readable_file(<string> name)
+\stopfunctioncall
+
+The return value is the actual absolute filename you should use, because the disk
+name is not always the same as the requested name, due to aliases and
+system|-|specific handling under e.g.\ \MSDOS.
+
+Returns \type {nil} if the file does not exist or is not readable.
+
+\subsection{\type {expand_path}}
+
+Like kpsewhich's \type {-expand-path}:
+
+\startfunctioncall
+<string> r = kpse.expand_path(<string> s)
+\stopfunctioncall
+
+\subsection{\type {expand_var}}
+
+Like kpsewhich's  \type {-expand-var}:
+
+\startfunctioncall
+<string> r = kpse.expand_var(<string> s)
+\stopfunctioncall
+
+\subsection{\type {expand_braces}}
+
+Like kpsewhich's \type {-expand-braces}:
+
+\startfunctioncall
+<string> r = kpse.expand_braces(<string> s)
+\stopfunctioncall
+
+\subsection{\type {show_path}}
+
+Like kpsewhich's \type {-show-path}:
+
+\startfunctioncall
+<string> r = kpse.show_path(<string> ftype)
+\stopfunctioncall
+
+
+\subsection{\type {var_value}}
+
+Like kpsewhich's \type {-var-value}:
+
+\startfunctioncall
+<string> r = kpse.var_value(<string> s)
+\stopfunctioncall
+
+\subsection{\type {version}}
+
+Returns the kpathsea version string.
+
+\startfunctioncall
+<string> r = kpse.version()
+\stopfunctioncall
+
+
+\section{The \type {lang} library}
+
+This library provides the interface to \LUATEX's structure
+representing a language, and the associated functions.
+
+\startfunctioncall
+<language> l = lang.new()
+<language> l = lang.new(<number> id)
+\stopfunctioncall
+
+This function creates a new userdata object. An object of type \type {<language>}
+is the first argument to most of the other functions in the \type {lang}
+library. These functions can also be used as if they were object methods, using
+the colon syntax.
+
+Without an argument, the next available internal id number will be assigned to
+this object. With argument, an object will be created that links to the internal
+language with that id number.
+
+\startfunctioncall
+<number> n = lang.id(<language> l)
+\stopfunctioncall
+
+returns the internal \type {\language} id number this object refers to.
+
+\startfunctioncall
+<string> n = lang.hyphenation(<language> l)
+lang.hyphenation(<language> l, <string> n)
+\stopfunctioncall
+
+Either returns the current hyphenation exceptions for this language, or adds new
+ones. The syntax of the string is explained in~\in {section}
+[patternsexceptions].
+
+\startfunctioncall
+lang.clear_hyphenation(<language> l)
+\stopfunctioncall
+
+Clears the exception dictionary for this language.
+
+\startfunctioncall
+<string> n = lang.clean(<string> o)
+\stopfunctioncall
+
+Creates a hyphenation key from the supplied hyphenation value. The syntax of the
+argument string is explained in~\in {section} [patternsexceptions]. This function
+is useful if you want to do something else based on the words in a dictionary
+file, like spell|-|checking.
+
+\startfunctioncall
+<string> n = lang.patterns(<language> l)
+lang.patterns(<language> l, <string> n)
+\stopfunctioncall
+
+Adds additional patterns for this language object, or returns the current set.
+The syntax of this string is explained in~\in {section} [patternsexceptions].
+
+\startfunctioncall
+lang.clear_patterns(<language> l)
+\stopfunctioncall
+
+Clears the pattern dictionary for this language.
+
+\startfunctioncall
+<number> n = lang.prehyphenchar(<language> l)
+lang.prehyphenchar(<language> l, <number> n)
+\stopfunctioncall
+
+Gets or sets the \quote {pre|-|break} hyphen character for implicit hyphenation
+in this language (initially the hyphen, decimal 45).
+
+\startfunctioncall
+<number> n = lang.posthyphenchar(<language> l)
+lang.posthyphenchar(<language> l, <number> n)
+\stopfunctioncall
+
+Gets or sets the \quote {post|-|break} hyphen character for implicit hyphenation
+in this language (initially null, decimal~0, indicating emptiness).
+
+\startfunctioncall
+<number> n = lang.preexhyphenchar(<language> l)
+lang.preexhyphenchar(<language> l, <number> n)
+\stopfunctioncall
+
+Gets or sets the \quote {pre|-|break} hyphen character for explicit hyphenation
+in this language (initially null, decimal~0, indicating emptiness).
+
+\startfunctioncall
+<number> n = lang.postexhyphenchar(<language> l)
+lang.postexhyphenchar(<language> l, <number> n)
+\stopfunctioncall
+
+Gets or sets the \quote {post|-|break} hyphen character for explicit hyphenation
+in this language (initially null, decimal~0, indicating emptiness).
+
+\startfunctioncall
+<boolean> success = lang.hyphenate(<node> head)
+<boolean> success = lang.hyphenate(<node> head, <node> tail)
+\stopfunctioncall
+
+Inserts hyphenation points (discretionary nodes) in a node list. If \type {tail}
+is given as argument, processing stops on that node. Currently, \type {success}
+is always true if \type {head} (and \type {tail}, if specified) are proper nodes,
+regardless of possible other errors.
+
+Hyphenation works only on \quote {characters}, a special subtype of all the glyph
+nodes with the node subtype having the value \type {1}. Glyph modes with
+different subtypes are not processed. See \in {section~} [charsandglyphs] for
+more details.
+
+\section{The \type {lua} library}
+
+This library contains one read|-|only  item:
+
+\starttyping
+<string> s = lua.version
+\stoptyping
+
+This returns the \LUA\ version identifier string. The value is currently
+\directlua {tex.print(lua.version)}.
+
+\subsection{\LUA\ bytecode registers}
+
+\LUA\ registers can be used to communicate \LUA\ functions across \LUA\ chunks.
+The accepted values for assignments are functions and \type {nil}. Likewise, the
+retrieved value is either a function or \type {nil}.
+
+\starttyping
+lua.bytecode[<number> n] = <function> f
+lua.bytecode[<number> n]()
+\stoptyping
+
+The contents of the \type {lua.bytecode} array is stored inside the format file
+as actual \LUA\ bytecode, so it can also be used to preload \LUA\ code.
+
+Note: The function must not contain any upvalues. Currently, functions containing
+upvalues can be stored (and their upvalues are set to \type {nil}), but this is
+an artifact of the current \LUA\ implementation and thus subject to change.
+
+The associated function calls are
+
+\startfunctioncall
+<function> f = lua.getbytecode(<number> n)
+lua.setbytecode(<number> n, <function> f)
+\stopfunctioncall
+
+Note: Since a \LUA\ file loaded using \type {loadfile(filename)} is essentially
+an anonymous function, a complete file can be stored in a bytecode register like
+this:
+
+\startfunctioncall
+lua.bytecode[n] = loadfile(filename)
+\stopfunctioncall
+
+Now all definitions (functions, variables) contained in the file can be
+created by executing this bytecode register:
+
+\startfunctioncall
+lua.bytecode[n]()
+\stopfunctioncall
+
+Note that the path of the file is stored in the \LUA\ bytecode to be used in
+stack backtraces and therefore dumped into the format file if the above code is
+used in \INITEX. If it contains private information, i.e. the user name, this
+information is then contained in the format file as well. This should be kept in
+mind when preloading files into a bytecode register in \INITEX.
+
+\subsection{\LUA\ chunk name registers}
+
+There is an array of 65536 (0--65535) potential chunk names for use with the
+\type {\directlua} and \type {\latelua} primitives.
+
+\startfunctioncall
+lua.name[<number> n] = <string> s
+<string> s = lua.name[<number> n]
+\stopfunctioncall
+
+If you want to unset a lua name, you can assign \type {nil} to it.
+
+\section{The \type {mplib} library}
+
+The \MP\ library interface registers itself in the table \type {mplib}. It is
+based on \MPLIB\ version \ctxlua {context(mplib.version())}.
+
+\subsection{\type {mplib.new}}
+
+To create a new \METAPOST\ instance, call
+
+\startfunctioncall
+<mpinstance> mp = mplib.new({...})
+\stopfunctioncall
+
+This creates the \type {mp} instance object. The argument hash can have a number
+of different fields, as follows:
+
+\starttabulate[|lT|l|p|p|]
+\NC \ssbf name  \NC \bf type \NC \bf description          \NC \bf default       \NC \NR
+\NC error_line  \NC number   \NC error line width         \NC 79                \NC \NR
+\NC print_line  \NC number   \NC line length in ps output \NC 100               \NC \NR
+\NC random_seed \NC number   \NC the initial random seed  \NC variable          \NC \NR
+\NC interaction \NC string   \NC the interaction mode,
+                                 one of
+                                 \type {batch},
+                                 \type {nonstop},
+                                 \type {scroll},
+                                 \type {errorstop}        \NC \type {errorstop} \NC \NR
+\NC job_name    \NC string   \NC \type {--jobname}        \NC \type {mpout}     \NC \NR
+\NC find_file   \NC function \NC a function to find files \NC only local files  \NC \NR
+\stoptabulate
+
+The \type {find_file} function should be of this form:
+
+\starttyping
+<string> found = finder (<string> name, <string> mode, <string> type)
+\stoptyping
+
+with:
+
+\starttabulate[|lT|l|p|]
+\NC \bf name \NC \bf the requested file \NC \NR
+\NC mode     \NC the file mode: \type {r} or \type {w} \NC \NR
+\NC type     \NC the kind of file, one of: \type {mp}, \type {tfm}, \type {map},
+                 \type {pfb}, \type {enc} \NC \NR
+\stoptabulate
+
+Return either the full pathname of the found file, or \type {nil} if the file
+cannot be found.
+
+Note that the new version of \MPLIB\ no longer uses binary mem files, so the way
+to preload a set of macros is simply to start off with an \type {input} command
+in the first \type {mp:execute()} call.
+
+\subsection{\type {mp:statistics}}
+
+You can request statistics with:
+
+\startfunctioncall
+<table> stats = mp:statistics()
+\stopfunctioncall
+
+This function returns the vital statistics for an \MPLIB\ instance. There are
+four fields, giving the maximum number of used items in each of four allocated
+object classes:
+
+\starttabulate[|lT|l|p|]
+\NC main_memory \NC number \NC memory size \NC \NR
+\NC hash_size   \NC number \NC hash size\NC \NR
+\NC param_size  \NC number \NC simultaneous macro parameters\NC \NR
+\NC max_in_open \NC number \NC input file nesting levels\NC \NR
+\stoptabulate
+
+Note that in the new version of \MPLIB, this is informational only. The objects
+are all allocated dynamically, so there is no chance of running out of space
+unless the available system memory is exhausted.
+
+\subsection{\type {mp:execute}}
+
+You can ask the \METAPOST\ interpreter to run a chunk of code by calling
+
+\startfunctioncall
+<table> rettable = mp:execute('metapost language chunk')
+\stopfunctioncall
+
+for various bits of \METAPOST\ language input. Be sure to check the \type
+{rettable.status} (see below) because when a fatal \METAPOST\ error occurs the
+\MPLIB\ instance will become unusable thereafter.
+
+Generally speaking, it is best to keep your chunks small, but beware that all
+chunks have to obey proper syntax, like each of them is a small file. For
+instance, you cannot split a single statement over multiple chunks.
+
+In contrast with the normal standalone \type {mpost} command, there is {\em no}
+implied \quote{input} at the start of the first chunk.
+
+\subsection{\type {mp:finish}}
+
+\startfunctioncall
+<table> rettable = mp:finish()
+\stopfunctioncall
+
+If for some reason you want to stop using an \MPLIB\ instance while processing is
+not yet actually done, you can call \type {mp:finish}. Eventually, used memory
+will be freed and open files will be closed by the \LUA\ garbage collector, but
+an explicit \type {mp:finish} is the only way to capture the final part of the
+output streams.
+
+\subsection{Result table}
+
+The return value of \type {mp:execute} and \type {mp:finish} is a table with a
+few possible keys (only \type {status} is always guaranteed to be present).
+
+\starttabulate[|l|l|p|]
+\NC log    \NC string \NC output to the \quote {log} stream \NC \NR
+\NC term   \NC string \NC output to the \quote {term} stream \NC \NR
+\NC error  \NC string \NC output to the \quote {error} stream
+                          (only used for \quote {out of memory}) \NC \NR
+\NC status \NC number \NC the return value:
+                          \type {0} = good,
+                          \type {1} = warning,
+                          \type {2} = errors,
+                          \type {3} = fatal error \NC \NR
+\NC fig    \NC table  \NC an array of generated figures (if any) \NC \NR
+\stoptabulate
+
+When \type {status} equals~3, you should stop using this \MPLIB\ instance
+immediately, it is no longer capable of processing input.
+
+If it is present, each of the entries in the \type {fig} array is a userdata
+representing a figure object, and each of those has a number of object methods
+you can call:
+
+\starttabulate[|l|l|p|]
+\NC boundingbox  \NC function \NC returns the bounding box, as an array of 4
+                                  values\NC \NR
+\NC postscript   \NC function \NC returns a string that is the ps output of the
+                                  \type {fig}. this function accepts two optional
+                                  integer arguments for specifying the values of
+                                  \type {prologues} (first argument) and \type
+                                  {procset} (second argument)\NC \NR
+\NC svg          \NC function \NC returns a string that is the svg output of the
+                                  \type {fig}. This function accepts an optional
+                                  integer argument for specifying the value of
+                                  \type {prologues}\NC \NR
+\NC objects      \NC function \NC returns the actual array of graphic objects in
+                                  this \type {fig} \NC \NR
+\NC copy_objects \NC function \NC returns a deep copy of the array of graphic
+                                  objects in this \type {fig} \NC \NR
+\NC filename     \NC function \NC the filename this \type {fig}'s \POSTSCRIPT\
+                                  output would have written to in standalone
+                                  mode \NC \NR
+\NC width        \NC function \NC the \type {fontcharwd} value \NC \NR
+\NC height       \NC function \NC the \type {fontcharht} value \NC \NR
+\NC depth        \NC function \NC the \type {fontchardp} value \NC \NR
+\NC italcorr     \NC function \NC the \type {fontcharit} value \NC \NR
+\NC charcode     \NC function \NC the (rounded) \type {charcode} value \NC \NR
+\stoptabulate
+
+Note: you can call \type {fig:objects()} only once for any one \type {fig}
+object!
+
+When the boundingbox represents a \quote {negated rectangle}, i.e.\ when the
+first set of coordinates is larger than the second set, the picture is empty.
+
+Graphical objects come in various types that each has a different list of
+accessible values. The types are: \type {fill}, \type {outline}, \type {text},
+\type {start_clip}, \type {stop_clip}, \type {start_bounds}, \type {stop_bounds},
+\type {special}.
+
+There is helper function (\type {mplib.fields(obj)}) to get the list of
+accessible values for a particular object, but you can just as easily use the
+tables given below.
+
+All graphical objects have a field \type {type} that gives the object type as a
+string value; it is not explicit mentioned in the following tables. In the
+following, \type {number}s are \POSTSCRIPT\ points represented as a floating
+point number, unless stated otherwise. Field values that are of type \type
+{table} are explained in the next section.
+
+\subsubsection{fill}
+
+\starttabulate[|l|l|p|]
+\NC path       \NC table  \NC the list of knots \NC \NR
+\NC htap       \NC table  \NC the list of knots for the reversed trajectory \NC \NR
+\NC pen        \NC table  \NC knots of the pen \NC \NR
+\NC color      \NC table  \NC the object's color \NC \NR
+\NC linejoin   \NC number \NC line join style (bare number)\NC \NR
+\NC miterlimit \NC number \NC miterlimit\NC \NR
+\NC prescript  \NC string \NC the prescript text \NC \NR
+\NC postscript \NC string \NC the postscript text \NC \NR
+\stoptabulate
+
+The entries \type {htap} and \type {pen} are optional.
+
+There is helper function (\type {mplib.pen_info(obj)}) that returns a table
+containing a bunch of vital characteristics of the used pen (all values are
+floats):
+
+\starttabulate[|l|l|p|]
+\NC width \NC number \NC width of the pen \NC \NR
+\NC sx    \NC number \NC $x$ scale        \NC \NR
+\NC rx    \NC number \NC $xy$ multiplier  \NC \NR
+\NC ry    \NC number \NC $yx$ multiplier  \NC \NR
+\NC sy    \NC number \NC $y$ scale        \NC \NR
+\NC tx    \NC number \NC $x$ offset       \NC \NR
+\NC ty    \NC number \NC $y$ offset       \NC \NR
+\stoptabulate
+
+\subsubsection{outline}
+
+\starttabulate[|l|l|p|]
+\NC path       \NC table  \NC the list of knots \NC \NR
+\NC pen        \NC table  \NC knots of the pen \NC \NR
+\NC color      \NC table  \NC the object's color \NC \NR
+\NC linejoin   \NC number \NC line join style (bare number) \NC \NR
+\NC miterlimit \NC number \NC miterlimit \NC \NR
+\NC linecap    \NC number \NC line cap style (bare number) \NC \NR
+\NC dash       \NC table  \NC representation of a dash list \NC \NR
+\NC prescript  \NC string \NC the prescript text \NC \NR
+\NC postscript \NC string \NC the postscript text \NC \NR
+\stoptabulate
+
+The entry \type {dash} is optional.
+
+\subsubsection{text}
+
+\starttabulate[|l|l|p|]
+\NC text       \NC string \NC the text \NC \NR
+\NC font       \NC string \NC font tfm name \NC \NR
+\NC dsize      \NC number \NC font size \NC \NR
+\NC color      \NC table  \NC the object's color \NC \NR
+\NC width      \NC number \NC \NC \NR
+\NC height     \NC number \NC \NC \NR
+\NC depth      \NC number \NC \NC \NR
+\NC transform  \NC table  \NC a text transformation \NC \NR
+\NC prescript  \NC string \NC the prescript text \NC \NR
+\NC postscript \NC string \NC the postscript text \NC \NR
+\stoptabulate
+
+\subsubsection{special}
+
+\starttabulate[|l|l|p|]
+\NC prescript \NC string \NC special text \NC \NR
+\stoptabulate
+
+\subsubsection{start_bounds, start_clip}
+
+\starttabulate[|l|l|p|]
+\NC path \NC table \NC the list of knots \NC \NR
+\stoptabulate
+
+\subsubsection{stop_bounds, stop_clip}
+
+Here are no fields available.
+
+\subsection{Subsidiary table formats}
+
+\subsubsection{Paths and pens}
+
+Paths and pens (that are really just a special type of paths as far as \MPLIB\ is
+concerned) are represented by an array where each entry is a table that
+represents a knot.
+
+\starttabulate[|lT|l|p|]
+\NC left_type   \NC string \NC when present: endpoint, but usually absent \NC \NR
+\NC right_type  \NC string \NC like \type {left_type} \NC \NR
+\NC x_coord     \NC number \NC X coordinate of this knot \NC \NR
+\NC y_coord     \NC number \NC Y coordinate of this knot \NC \NR
+\NC left_x      \NC number \NC X coordinate of the precontrol point of this knot \NC \NR
+\NC left_y      \NC number \NC Y coordinate of the precontrol point of this knot \NC \NR
+\NC right_x     \NC number \NC X coordinate of the postcontrol point of this knot \NC \NR
+\NC right_y     \NC number \NC Y coordinate of the postcontrol point of this knot \NC \NR
+\stoptabulate
+
+There is one special case: pens that are (possibly transformed) ellipses have an
+extra string-valued key \type {type} with value \type {elliptical} besides the
+array part containing the knot list.
+
+\subsubsection{Colors}
+
+A color is an integer array with 0, 1, 3 or 4 values:
+
+\starttabulate[|l|l|p|]
+\NC 0 \NC marking only \NC no values                                                     \NC \NR
+\NC 1 \NC greyscale    \NC one value in the range $(0,1)$, \quote {black} is $0$         \NC \NR
+\NC 3 \NC \RGB         \NC three values in the range $(0,1)$, \quote {black} is $0,0,0$  \NC \NR
+\NC 4 \NC \CMYK        \NC four values in the range $(0,1)$, \quote {black} is $0,0,0,1$ \NC \NR
+\stoptabulate
+
+If the color model of the internal object was \type {uninitialized}, then it was
+initialized to the values representing \quote {black} in the colorspace \type
+{defaultcolormodel} that was in effect at the time of the \type {shipout}.
+
+\subsubsection{Transforms}
+
+Each transform is a six|-|item array.
+
+\starttabulate[|l|l|p|]
+\NC 1 \NC number \NC represents x  \NC \NR
+\NC 2 \NC number \NC represents y  \NC \NR
+\NC 3 \NC number \NC represents xx \NC \NR
+\NC 4 \NC number \NC represents yx \NC \NR
+\NC 5 \NC number \NC represents xy \NC \NR
+\NC 6 \NC number \NC represents yy \NC \NR
+\stoptabulate
+
+Note that the translation (index 1 and 2) comes first. This differs from the
+ordering in \POSTSCRIPT, where the translation comes last.
+
+\subsubsection{Dashes}
+
+Each \type {dash} is two-item hash, using the same model as \POSTSCRIPT\ for the
+representation of the dashlist. \type {dashes} is an array of \quote {on} and
+\quote {off}, values, and \type {offset} is the phase of the pattern.
+
+\starttabulate[|l|l|p|]
+\NC dashes \NC hash   \NC an array of on-off numbers \NC \NR
+\NC offset \NC number \NC the starting offset value  \NC \NR
+\stoptabulate
+
+\subsection{Character size information}
+
+These functions find the size of a glyph in a defined font. The \type {fontname}
+is the same name as the argument to \type {infont}; the \type {char} is a glyph
+id in the range 0 to 255; the returned \type {w} is in AFM units.
+
+\subsubsection{\type {mp:char_width}}
+
+\startfunctioncall
+<number> w = mp:char_width(<string> fontname, <number> char)
+\stopfunctioncall
+
+\subsubsection{\type {mp:char_height}}
+
+\startfunctioncall
+<number> w = mp:char_height(<string> fontname, <number> char)
+\stopfunctioncall
+
+\subsubsection{\type {mp:char_depth}}
+
+\startfunctioncall
+<number> w = mp:char_depth(<string> fontname, <number> char)
+\stopfunctioncall
+
+\section{The \type {node} library}
+
+The \type {node} library contains functions that facilitate dealing with (lists
+of) nodes and their values. They allow you to create, alter, copy, delete, and
+insert \LUATEX\ node objects, the core objects within the typesetter.
+
+\LUATEX\ nodes are represented in \LUA\ as userdata with the metadata type
+\type {luatex.node}. The various parts within a node can be accessed using
+named fields.
+
+Each node has at least the three fields \type {next}, \type {id}, and \type
+{subtype}:
+
+\startitemize[intro]
+
+\startitem
+    The \type {next} field returns the userdata object for the next node in a
+    linked list of nodes, or \type {nil}, if there is no next node.
+\stopitem
+
+\startitem
+    The \type {id} indicates \TEX's \quote{node type}. The field \type {id} has a
+    numeric value for efficiency reasons, but some of the library functions also
+    accept a string value instead of \type {id}.
+\stopitem
+
+\startitem
+    The \type {subtype} is another number. It often gives further information
+    about a node of a particular \type {id}, but it is most important when
+    dealing with \quote {whatsits}, because they are differentiated solely based
+    on their \type {subtype}.
+\stopitem
+
+\stopitemize
+
+The other available fields depend on the \type {id} (and for \quote {whatsits},
+the \type {subtype}) of the node. Further details on the various fields and their
+meanings are given in~\in{chapter}[nodes].
+
+Support for \type {unset} (alignment) nodes is partial: they can be queried and
+modified from \LUA\ code, but not created.
+
+Nodes can be compared to each other, but: you are actually comparing indices into
+the node memory. This means that equality tests can only be trusted under very
+limited conditions. It will not work correctly in any situation where one of the
+two nodes has been freed and|/|or reallocated: in that case, there will be false
+positives.
+
+At the moment, memory management of nodes should still be done explicitly by the
+user. Nodes are not \quote {seen} by the \LUA\ garbage collector, so you have to
+call the node freeing functions yourself when you are no longer in need of a node
+(list). Nodes form linked lists without reference counting, so you have to be
+careful that when control returns back to \LUATEX\ itself, you have not deleted
+nodes that are still referenced from a \type {next} pointer elsewhere, and that
+you did not create nodes that are referenced more than once.
+
+There are statistics available with regards to the allocated node memory, which
+can be handy for tracing.
+
+\subsection{Node handling functions}
+
+\subsubsection{\type {node.is_node}}
+
+\startfunctioncall
+<boolean> t = node.is_node(<any> item)
+\stopfunctioncall
+
+This function returns true if the argument is a userdata object of
+type \type {<node>}.
+
+\subsubsection{\type {node.types}}
+
+\startfunctioncall
+<table> t = node.types()
+\stopfunctioncall
+
+This function returns an array that maps node id numbers to node type strings,
+providing an overview of the possible top|-|level \type {id} types.
+
+\subsubsection{\type {node.whatsits}}
+
+\startfunctioncall
+<table> t = node.whatsits()
+\stopfunctioncall
+
+\TEX's \quote{whatsits} all have the same \type {id}. The various subtypes are
+defined by their \type {subtype} fields. The function is much like \type
+{node.types}, except that it provides an array of \type {subtype} mappings.
+
+\subsubsection{\type {node.id}}
+
+\startfunctioncall
+<number> id = node.id(<string> type)
+\stopfunctioncall
+
+This converts a single type name to its internal numeric representation.
+
+\subsubsection{\type {node.subtype}}
+
+\startfunctioncall
+<number> subtype = node.subtype(<string> type)
+\stopfunctioncall
+
+This converts a single whatsit name to its internal numeric representation (\type
+{subtype}).
+
+\subsubsection{\type {node.type}}
+
+\startfunctioncall
+<string> type = node.type(<any> n)
+\stopfunctioncall
+
+In the argument is a number, then this function converts an internal numeric
+representation to an external string representation. Otherwise, it will return
+the string \type {node} if the object represents a node, and \type {nil}
+otherwise.
+
+\subsubsection{\type {node.fields}}
+
+\startfunctioncall
+<table> t = node.fields(<number> id)
+<table> t = node.fields(<number> id, <number> subtype)
+\stopfunctioncall
+
+This function returns an array of valid field names for a particular type of
+node. If you want to get the valid fields for a \quote {whatsit}, you have to
+supply the second argument also. In other cases, any given second argument will
+be silently ignored.
+
+This function accepts string \type {id} and \type {subtype} values as well.
+
+\subsubsection{\type {node.has_field}}
+
+\startfunctioncall
+<boolean> t = node.has_field(<node> n, <string> field)
+\stopfunctioncall
+
+This function returns a boolean that is only true if \type {n} is
+actually a node, and it has the field.
+
+\subsubsection{\type {node.new}}
+
+\startfunctioncall
+<node> n = node.new(<number> id)
+<node> n = node.new(<number> id, <number> subtype)
+\stopfunctioncall
+
+Creates a new node. All of the new node's fields are initialized to either zero
+or \type {nil} except for \type {id} and \type {subtype} (if supplied). If you
+want to create a new whatsit, then the second argument is required, otherwise it
+need not be present. As with all node functions, this function creates a node on
+the \TEX\ level.
+
+This function accepts string \type {id} and \type {subtype} values as well.
+
+\subsubsection{\type {node.free}}
+
+\startfunctioncall
+node.free(<node> n)
+\stopfunctioncall
+
+Removes the node \type {n} from \TEX's memory. Be careful: no checks are done on
+whether this node is still pointed to from a register or some \type {next} field:
+it is up to you to make sure that the internal data structures remain correct.
+
+\subsubsection{\type {node.flush_list}}
+
+\startfunctioncall
+node.flush_list(<node> n)
+\stopfunctioncall
+
+Removes the node list \type {n} and the complete node list following \type {n}
+from \TEX's memory. Be careful: no checks are done on whether any of these nodes
+is still pointed to from a register or some \type {next} field: it is up to you
+to make sure that the internal data structures remain correct.
+
+\subsubsection{\type {node.copy}}
+
+\startfunctioncall
+<node> m = node.copy(<node> n)
+\stopfunctioncall
+
+Creates a deep copy of node \type {n}, including all nested lists as in the case
+of a hlist or vlist node. Only the \type {next} field is not copied.
+
+\subsubsection{\type {node.copy_list}}
+
+\startfunctioncall
+<node> m = node.copy_list(<node> n)
+<node> m = node.copy_list(<node> n, <node> m)
+\stopfunctioncall
+
+Creates a deep copy of the node list that starts at \type {n}. If \type {m} is
+also given, the copy stops just before node \type {m}.
+
+Note that you cannot copy attribute lists this way, specialized functions for
+dealing with attribute lists will be provided later but are not there yet.
+However, there is normally no need to copy attribute lists as when you do
+assignments to the \type {attr} field or make changes to specific attributes, the
+needed copying and freeing takes place automatically.
+
+\subsubsection{\type {node.next}}
+
+\startfunctioncall
+<node> m = node.next(<node> n)
+\stopfunctioncall
+
+Returns the node following this node, or \type {nil} if there is no such node.
+
+\subsubsection{\type {node.prev}}
+
+\startfunctioncall
+<node> m = node.prev(<node> n)
+\stopfunctioncall
+
+Returns the node preceding this node, or \type {nil} if there is no such node.
+
+\subsubsection{\type {node.current_attr}}
+
+\startfunctioncall
+<node> m = node.current_attr()
+\stopfunctioncall
+
+Returns the currently active list of attributes, if there is one.
+
+The intended usage of \type {current_attr} is as follows:
+
+\starttyping
+local x1 = node.new("glyph")
+x1.attr = node.current_attr()
+local x2 = node.new("glyph")
+x2.attr = node.current_attr()
+\stoptyping
+
+or:
+
+\starttyping
+local x1 = node.new("glyph")
+local x2 = node.new("glyph")
+local ca = node.current_attr()
+x1.attr = ca
+x2.attr = ca
+\stoptyping
+
+The attribute lists are ref counted and the assignment takes care of incrementing
+the refcount. You cannot expect the value \type {ca} to be valid any more when
+you assign attributes (using \type {tex.setattribute}) or when control has been
+passed back to \TEX.
+
+Note: this function is somewhat experimental, and it returns the {\it actual}
+attribute list, not a copy thereof. Therefore, changing any of the attributes in
+the list will change these values for all nodes that have the current attribute
+list assigned to them.
+
+\subsubsection{\type {node.hpack}}
+
+\startfunctioncall
+<node> h, <number> b = node.hpack(<node> n)
+<node> h, <number> b = node.hpack(<node> n, <number> w, <string> info)
+<node> h, <number> b = node.hpack(<node> n, <number> w, <string> info, <string> dir)
+\stopfunctioncall
+
+This function creates a new hlist by packaging the list that begins at node \type
+{n} into a horizontal box. With only a single argument, this box is created using
+the natural width of its components. In the three argument form, \type {info}
+must be either \type {additional} or \type {exactly}, and \type {w} is the
+additional (\type {\hbox spread}) or exact (\type {\hbox to}) width to be used. The
+second return value is the badness of the generated box.
+
+Caveat: at this moment, there can be unexpected side|-|effects to this function,
+like updating some of the \type {\marks} and \type {\inserts}. Also note that the
+content of \type {h} is the original node list \type {n}: if you call \type
+{node.free(h)} you will also free the node list itself, unless you explicitly set
+the \type {list} field to \type {nil} beforehand. And in a similar way, calling
+\type {node.free(n)} will invalidate \type {h} as well!
+
+\subsubsection{\type {node.vpack}}
+
+\startfunctioncall
+<node> h, <number> b = node.vpack(<node> n)
+<node> h, <number> b = node.vpack(<node> n, <number> w, <string> info)
+<node> h, <number> b = node.vpack(<node> n, <number> w, <string> info, <string> dir)
+\stopfunctioncall
+
+This function creates a new vlist by packaging the list that begins at node \type
+{n} into a vertical box. With only a single argument, this box is created using
+the natural height of its components. In the three argument form, \type {info}
+must be either \type {additional} or \type {exactly}, and \type {w} is the
+additional (\type {\vbox spread}) or exact (\type {\vbox to}) height to be used.
+
+The second return value is the badness of the generated box.
+
+See the description of \type {node.hpack()} for a few memory allocation caveats.
+
+\subsubsection{\type {node.dimensions}}
+
+\startfunctioncall
+<number> w, <number> h, <number> d  = node.dimensions(<node> n)
+<number> w, <number> h, <number> d  = node.dimensions(<node> n, <string> dir)
+<number> w, <number> h, <number> d  = node.dimensions(<node> n, <node> t)
+<number> w, <number> h, <number> d  = node.dimensions(<node> n, <node> t, <string> dir)
+\stopfunctioncall
+
+This function calculates the natural in-line dimensions of the node list starting
+at node \type {n} and terminating just before node \type {t} (or the end of the
+list, if there is no second argument). The return values are scaled points. An
+alternative format that starts with glue parameters as the first three arguments
+is also possible:
+
+\startfunctioncall
+<number> w, <number> h, <number> d  =
+  node.dimensions(<number> glue_set, <number> glue_sign,
+                 <number> glue_order, <node> n)
+<number> w, <number> h, <number> d  =
+  node.dimensions(<number> glue_set, <number> glue_sign,
+                 <number> glue_order, <node> n, <string> dir)
+<number> w, <number> h, <number> d  =
+  node.dimensions(<number> glue_set, <number> glue_sign,
+                 <number> glue_order, <node> n, <node> t)
+<number> w, <number> h, <number> d  =
+  node.dimensions(<number> glue_set, <number> glue_sign,
+                 <number> glue_order, <node> n, <node> t, <string> dir)
+\stopfunctioncall
+
+This calling method takes glue settings into account and is especially useful for
+finding the actual width of a sublist of nodes that are already boxed, for
+example in code like this, which prints the width of the space inbetween the
+\type {a} and \type {b} as it would be if \type {\box0} was used as-is:
+
+\starttyping
+\setbox0 = \hbox to 20pt {a b}
+
+\directlua{print (node.dimensions(
+    tex.box[0].glue_set,
+    tex.box[0].glue_sign,
+    tex.box[0].glue_order,
+    tex.box[0].head.next,
+    node.tail(tex.box[0].head)
+)) }
+\stoptyping
+
+\subsubsection{\type {node.mlist_to_hlist}}
+
+\startfunctioncall
+<node> h = node.mlist_to_hlist(<node> n,
+             <string> display_type, <boolean> penalties)
+\stopfunctioncall
+
+This runs the internal mlist to hlist conversion, converting the math list in
+\type {n} into the horizontal list \type {h}. The interface is exactly the same
+as for the callback \type {mlist_to_hlist}.
+
+\subsubsection{\type {node.slide}}
+
+\startfunctioncall
+<node> m = node.slide(<node> n)
+\stopfunctioncall
+
+Returns the last node of the node list that starts at \type {n}. As a
+side|-|effect, it also creates a reverse chain of \type {prev} pointers between
+nodes.
+
+\subsubsection{\type {node.tail}}
+
+\startfunctioncall
+<node> m = node.tail(<node> n)
+\stopfunctioncall
+
+Returns the last node of the node list that starts at \type {n}.
+
+\subsubsection{\type {node.length}}
+
+\startfunctioncall
+<number> i = node.length(<node> n)
+<number> i = node.length(<node> n, <node> m)
+\stopfunctioncall
+
+Returns the number of nodes contained in the node list that starts at \type {n}.
+If \type {m} is also supplied it stops at \type {m} instead of at the end of the
+list. The node \type {m} is not counted.
+
+\subsubsection{\type {node.count}}
+
+\startfunctioncall
+<number> i = node.count(<number> id, <node> n)
+<number> i = node.count(<number> id, <node> n, <node> m)
+\stopfunctioncall
+
+Returns the number of nodes contained in the node list that starts at \type {n}
+that have a matching \type {id} field. If \type {m} is also supplied, counting
+stops at \type {m} instead of at the end of the list. The node \type {m} is not
+counted.
+
+This function also accept string \type {id}'s.
+
+\subsubsection{\type {node.traverse}}
+
+\startfunctioncall
+<node> t = node.traverse(<node> n)
+\stopfunctioncall
+
+This is a lua iterator that loops over the node list that starts at \type {n}.
+Typically code looks like this:
+
+\starttyping
+for n in node.traverse(head) do
+   ...
+end
+\stoptyping
+
+is functionally equivalent to:
+
+\starttyping
+do
+  local n
+  local function f (head,var)
+    local t
+    if var == nil then
+       t = head
+    else
+       t = var.next
+    end
+    return t
+  end
+  while true do
+    n = f (head, n)
+    if n == nil then break end
+    ...
+  end
+end
+\stoptyping
+
+It should be clear from the definition of the function \type {f} that even though
+it is possible to add or remove nodes from the node list while traversing, you
+have to take great care to make sure all the \type {next} (and \type {prev})
+pointers remain valid.
+
+If the above is unclear to you, see the section \quote {For Statement} in the
+\LUA\ Reference Manual.
+
+\subsubsection{\type {node.traverse_id}}
+
+\startfunctioncall
+<node> t = node.traverse_id(<number> id, <node> n)
+\stopfunctioncall
+
+This is an iterator that loops over all the nodes in the list that starts at
+\type {n} that have a matching \type {id} field.
+
+See the previous section for details. The change is in the local function \type
+{f}, which now does an extra while loop checking against the upvalue \type {id}:
+
+\starttyping
+ local function f(head,var)
+   local t
+   if var == nil then
+      t = head
+   else
+      t = var.next
+   end
+   while not t.id == id do
+      t = t.next
+   end
+   return t
+ end
+\stoptyping
+
+\subsubsection{\type {node.end_of_math}}
+
+\startfunctioncall
+<node> t = node.end_of_math(<node> start)
+\stopfunctioncall
+
+Looks for and returns the next \type {math_node} following the \type {start}. If
+the given node is a math endnode this helper return that node, else it follows
+the list and return the next math endnote. If no such node is found nil is
+returned.
+
+\subsubsection{\type {node.remove}}
+
+\startfunctioncall
+<node> head, current = node.remove(<node> head, <node> current)
+\stopfunctioncall
+
+This function removes the node \type {current} from the list following \type
+{head}. It is your responsibility to make sure it is really part of that list.
+The return values are the new \type {head} and \type {current} nodes. The
+returned \type {current} is the node following the \type {current} in the calling
+argument, and is only passed back as a convenience (or \type {nil}, if there is
+no such node). The returned \type {head} is more important, because if the
+function is called with \type {current} equal to \type {head}, it will be
+changed.
+
+\subsubsection{\type {node.insert_before}}
+
+\startfunctioncall
+<node> head, new = node.insert_before(<node> head, <node> current, <node> new)
+\stopfunctioncall
+
+This function inserts the node \type {new} before \type {current} into the list
+following \type {head}. It is your responsibility to make sure that \type
+{current} is really part of that list. The return values are the (potentially
+mutated) \type {head} and the node \type {new}, set up to be part of the list
+(with correct \type {next} field). If \type {head} is initially \type {nil}, it
+will become \type {new}.
+
+\subsubsection{\type {node.insert_after}}
+
+\startfunctioncall
+<node> head, new = node.insert_after(<node> head, <node> current, <node> new)
+\stopfunctioncall
+
+This function inserts the node \type {new} after \type {current} into the list
+following \type {head}. It is your responsibility to make sure that \type
+{current} is really part of that list. The return values are the \type {head} and
+the node \type {new}, set up to be part of the list (with correct \type {next}
+field). If \type {head} is initially \type {nil}, it will become \type {new}.
+
+\subsubsection{\type {node.first_glyph}}
+
+\startfunctioncall
+<node> n = node.first_glyph(<node> n)
+<node> n = node.first_glyph(<node> n, <node> m)
+\stopfunctioncall
+
+Returns the first node in the list starting at \type {n} that is a glyph node
+with a subtype indicating it is a glyph, or \type {nil}. If \type {m} is given,
+processing stops at (but including) that node, otherwise processing stops at the
+end of the list.
+
+\subsubsection{\type {node.ligaturing}}
+
+\startfunctioncall
+<node> h, <node> t, <boolean> success = node.ligaturing(<node> n)
+<node> h, <node> t, <boolean> success = node.ligaturing(<node> n, <node> m)
+\stopfunctioncall
+
+Apply \TEX-style ligaturing to the specified nodelist. The tail node \type {m} is
+optional. The two returned nodes \type {h} and \type {t} are the new head and
+tail (both \type {n} and \type {m} can change into a new ligature).
+
+\subsubsection{\type {node.kerning}}
+
+\startfunctioncall
+<node> h, <node> t, <boolean> success = node.kerning(<node> n)
+<node> h, <node> t, <boolean> success = node.kerning(<node> n, <node> m)
+\stopfunctioncall
+
+Apply \TEX|-|style kerning to the specified nodelist. The tail node \type {m} is
+optional. The two returned nodes \type {h} and \type {t} are the head and tail
+(either one of these can be an inserted kern node, because special kernings with
+word boundaries are possible).
+
+\subsubsection{\type {node.unprotect_glyphs}}
+
+\startfunctioncall
+node.unprotect_glyphs(<node> n)
+\stopfunctioncall
+
+Subtracts 256 from all glyph node subtypes. This and the next function are
+helpers to convert from \type {characters} to \type {glyphs} during node
+processing.
+
+\subsubsection{\type {node.protect_glyphs}}
+
+\startfunctioncall
+node.protect_glyphs(<node> n)
+\stopfunctioncall
+
+Adds 256 to all glyph node subtypes in the node list starting at \type {n},
+except that if the value is 1, it adds only 255. The special handling of 1 means
+that \type {characters} will become \type {glyphs} after subtraction of 256.
+
+\subsubsection{\type {node.last_node}}
+
+\startfunctioncall
+<node> n = node.last_node()
+\stopfunctioncall
+
+This function pops the last node from \TEX's \quote{current list}. It returns
+that node, or \type {nil} if the current list is empty.
+
+\subsubsection{\type {node.write}}
+
+\startfunctioncall
+node.write(<node> n)
+\stopfunctioncall
+
+This is an experimental function that will append a node list to \TEX's \quote
+{current list} The node list is not deep|-|copied! There is no error checking
+either!
+
+\subsubsection{\type {node.protrusion_skippable}}
+\startfunctioncall
+<boolean> skippable = node.protrusion_skippable(<node> n)
+\stopfunctioncall
+
+Returns \type {true} if, for the purpose of line boundary discovery when
+character protrusion is active, this node can be skipped.
+
+\subsection{Attribute handling}
+
+Attributes appear as linked list of userdata objects in the \type {attr} field of
+individual nodes. They can be handled individually, but it is much safer and more
+efficient to use the dedicated functions associated with them.
+
+\subsubsection{\type {node.has_attribute}}
+
+\startfunctioncall
+<number> v = node.has_attribute(<node> n, <number> id)
+<number> v = node.has_attribute(<node> n, <number> id, <number> val)
+\stopfunctioncall
+
+Tests if a node has the attribute with number \type {id} set. If \type {val} is
+also supplied, also tests if the value matches \type {val}. It returns the value,
+or, if no match is found, \type {nil}.
+
+\subsubsection{\type {node.set_attribute}}
+
+\startfunctioncall
+node.set_attribute(<node> n, <number> id, <number> val)
+\stopfunctioncall
+
+Sets the attribute with number \type {id} to the value \type {val}. Duplicate
+assignments are ignored. {\em [needs explanation]}
+
+\subsubsection{\type {node.unset_attribute}}
+
+\startfunctioncall
+<number> v = node.unset_attribute(<node> n, <number> id)
+<number> v = node.unset_attribute(<node> n, <number> id, <number> val)
+\stopfunctioncall
+
+Unsets the attribute with number \type {id}. If \type {val} is also supplied, it
+will only perform this operation if the value matches \type {val}. Missing
+attributes or attribute|-|value pairs are ignored.
+
+If the attribute was actually deleted, returns its old value. Otherwise, returns
+\type {nil}.
+
+\section{The \type {pdf} library}
+
+This contains variables and functions that are related to the \PDF\ backend.
+
+\subsection{\type {pdf.mapfile}, \type {pdf.mapline}}
+
+\startfunctioncall
+pdf.mapfile(<string> map file)
+pdf.mapline(<string> map line)
+\stopfunctioncall
+
+These two functions can be used to replace primitives \type {\pdfmapfile} and
+\type {\pdfmapline} from \PDFTEX. They expect a string as only parameter and have
+no return value.
+
+The also functions replace the former variables \type {pdf.pdfmapfile} and
+\type {pdf.pdfmapline}.
+
+\subsection{\type {pdf.catalog}, \type {pdf.info},\type {pdf.names},
+    \type {pdf.trailer}}
+
+These variables offer a read|-|write interface to the corresponding \PDFTEX\
+token lists. The value types are strings and they are written out to the \PDF\
+file directly after the \PDFTEX\ token registers.
+
+The preferred interface is now \type {pdf.setcatalog}, \type {pdf.setinfo}
+\type {pdf.setnames} and \type {pdf.settrailer} for setting these properties
+and \type {pdf.getcatalog}, \type {pdf.getinfo} \type {pdf.getnames} and
+\type {pdf.gettrailer} for querying them,
+
+The corresponding \quote {\type {pdf}} parameter names \type {pdf.pdfcatalog},
+\type {pdf.pdfinfo}, \type {pdf.pdfnames}, and \type {pdf.pdftrailer} are
+not available.
+
+\subsection{\type {pdf.<set/get>pageattributes}, \type {pdf.<set/get>pageresources},
+    \type {pdf.<set/get>pagesattributes}}
+
+These variables offer a read|-|write interface to related token lists. The value
+types are strings. The variables have no interaction with the corresponding
+\PDFTEX\ token registers \type {\pdfpageattr}, \type {\pdfpageresources}, and \type
+{\pdfpagesattr}. They are written out to the \PDF\ file directly after the
+\PDFTEX\ token registers.
+
+The preferred interface is now \type {pdf.setpageattributes}, \type
+{pdf.setpagesattributes} and \type {pdf.setpageresources} for setting these
+properties and \type {pdf.getpageattributes}, \type {pdf.getpageattributes}
+and \type {pdf.getpageresources} for querying them.
+
+\subsection{\type {pdf.h}, \type {pdf.v}}
+
+These are the \type {h} and \type {v} values that define the current location on
+the output page, measured from its lower left corner. The values can be queried
+using scaled points as units.
+
+\starttyping
+local h = pdf.h
+local v = pdf.v
+\stoptyping
+
+\subsection{\type {pdf.getpos}, \type {pdf.gethpos}, \type {pdf.getvpos}}
+
+These are the function variants of \type {pdf.h} and \type {pdf.v}. Sometimes
+using a function is preferred over a key so this saves wrapping. Also, these
+functions are faster then the key based access, as \type {h} and \type {v} keys
+are not real variables but looked up using a metatable call. The \type {getpos}
+function returns two values, the other return one.
+
+\starttyping
+local h, v = pdf.getpos()
+\stoptyping
+
+\subsection{\type {pdf.hasmatrix}, \type {pdf.getmatrix}}
+
+The current matrix transformation is available via the \type {getmatrix} command,
+which returns 6 values: \type {sx}, \type {rx}, \type {ry}, \type {sy}, \type
+{tx}, and \type {ty}. The \type {hasmatrix} function returns \type {true} when a
+matrix is applied.
+
+\starttyping
+if pdf.hasmatrix() then
+    local sx, rx, ry, sy, tx, ty = pdf.getmatrix()
+    -- do something useful or not
+end
+\stoptyping
+
+\subsection{\type {pdf.print}}
+
+A print function to write stuff to the \PDF\ document that can be used from
+within a \type {\latelua} argument. This function is not to be used inside
+\type {\directlua} unless you know {\it exactly} what you are doing.
+
+\startfunctioncall
+pdf.print(<string> s)
+pdf.print(<string> type, <string> s)
+\stopfunctioncall
+
+The optional parameter can be used to mimic the behavior of \type {\pdfliteral}:
+the \type {type} is \type {direct} or \type {page}.
+
+\subsection{\type {pdf.immediateobj}}
+
+This function creates a \PDF\ object and immediately writes it to the \PDF\ file.
+It is modelled after \PDFTEX's \type {\immediate} \type {\pdfobj} primitives. All
+function variants return the object number of the newly generated object.
+
+\startfunctioncall
+<number> n = pdf.immediateobj(<string> objtext)
+<number> n = pdf.immediateobj("file", <string> filename)
+<number> n = pdf.immediateobj("stream", <string> streamtext, <string> attrtext)
+<number> n = pdf.immediateobj("streamfile", <string> filename, <string> attrtext)
+\stopfunctioncall
+
+The first version puts the \type {objtext} raw into an object. Only the object
+wrapper is automatically generated, but any internal structure (like \type {<<
+>>} dictionary markers) needs to provided by the user. The second version with
+keyword \type {"file"} as 1st argument puts the contents of the file with name
+\type {filename} raw into the object. The third version with keyword \type
+{"stream"} creates a stream object and puts the \type {streamtext} raw into the
+stream. The stream length is automatically calculated. The optional \type
+{attrtext} goes into the dictionary of that object. The fourth version with
+keyword \type {"streamfile"} does the same as the 3rd one, it just reads the
+stream data raw from a file.
+
+An optional first argument can be given to make the function use a previously
+reserved \PDF\ object.
+
+\startfunctioncall
+<number> n = pdf.immediateobj(<integer> n, <string> objtext)
+<number> n = pdf.immediateobj(<integer> n, "file", <string> filename)
+<number> n = pdf.immediateobj(<integer> n, "stream", <string> streamtext, <string> attrtext)
+<number> n = pdf.immediateobj(<integer> n, "streamfile", <string> filename, <string> attrtext)
+\stopfunctioncall
+
+\subsection{\type {pdf.obj}}
+
+This function creates a \PDF\ object, which is written to the \PDF\ file only
+when referenced, e.g., by \type {pdf.refobj()}.
+
+All function variants return the object number of the newly generated object, and
+there are two separate calling modes.
+
+The first mode is modelled after \PDFTEX's \type {\pdfobj} primitive.
+
+\startfunctioncall
+<number> n = pdf.obj(<string> objtext)
+<number> n = pdf.obj("file", <string> filename)
+<number> n = pdf.obj("stream", <string> streamtext, <string> attrtext)
+<number> n = pdf.obj("streamfile", <string> filename, <string> attrtext)
+\stopfunctioncall
+
+An optional first argument can be given to make the function use a previously
+reserved \PDF\ object.
+
+\startfunctioncall
+<number> n = pdf.obj(<integer> n, <string> objtext)
+<number> n = pdf.obj(<integer> n, "file", <string> filename)
+<number> n = pdf.obj(<integer> n, "stream", <string> streamtext, <string> attrtext)
+<number> n = pdf.obj(<integer> n, "streamfile", <string> filename, <string> attrtext)
+\stopfunctioncall
+
+The second mode accepts a single argument table with key--value pairs.
+
+\startfunctioncall
+<number> n = pdf.obj {
+    type           = <string>,
+    immmediate     = <boolean>,
+    objnum         = <number>,
+    attr           = <string>,
+    compresslevel  = <number>,
+    objcompression = <boolean>,
+    file           = <string>,
+    string         = <string>
+}
+\stopfunctioncall
+
+The \type {type} field can have the values \type {raw} and \type {stream}, this
+field is required, the others are optional (within constraints).
+
+Note: this mode makes \type {pdf.obj} look more flexible than it actually is: the
+constraints from the separate parameter version still apply, so for example you
+can't have both \type {string} and \type {file} at the same time.
+
+\subsection{\type {pdf.refobj}}
+
+This function, the \LUA\ version of the \type {\pdfrefobj} primitive, references an
+object by its object number, so that the object will be written out.
+
+\startfunctioncall
+pdf.refobj(<integer> n)
+\stopfunctioncall
+
+This function works in both the \type {\directlua} and \type {\latelua} environment.
+Inside \type {\directlua} a new whatsit node \quote {pdf_refobj} is created, which
+will be marked for flushing during page output and the object is then written
+directly after the page, when also the resources objects are written out. Inside
+\type {\latelua} the object will be marked for flushing.
+
+This function has no return values.
+
+\subsection{\type {pdf.reserveobj}}
+
+This function creates an empty \PDF\ object and returns its number.
+
+\startfunctioncall
+<number> n = pdf.reserveobj()
+<number> n = pdf.reserveobj("annot")
+\stopfunctioncall
+
+\subsection{\type {pdf.registerannot}}
+
+This function adds an object number to the \type {/Annots} array for the current
+page without doing anything else. This function can only be used from within
+\type {\latelua}.
+
+\startfunctioncall
+pdf.registerannot (<number> objnum)
+\stopfunctioncall
+
+\section{The \type {pdfscanner} library}
+
+The \type {pdfscanner} library allows interpretation of PDF content streams and
+\type {/ToUnicode} (cmap) streams. You can get those streams from the \type
+{epdf} library, as explained in an earlier section. There is only a single
+top|-|level function in this library:
+
+\startfunctioncall
+pdfscanner.scan (<Object> stream, <table> operatortable, <table> info)
+\stopfunctioncall
+
+The first argument, \type {stream}, should be either a PDF stream object, or a
+PDF array of PDF stream objects (those options comprise the possible return
+values of \type {<Page>:getContents()} and \type {<Object>:getStream()} in the
+\type {epdf} library).
+
+The second argument, \type {operatortable}, should be a Lua table where the keys
+are PDF operator name strings and the values are Lua functions (defined by you)
+that are used to process those operators. The functions are called whenever the
+scanner finds one of these PDF operators in the content stream(s). The functions
+are called with two arguments: the \type {scanner} object itself, and the \type
+{info} table that was passed are the third argument to \type {pdfscanner.scan}.
+
+Internally, \type {pdfscanner.scan} loops over the PDF operators in the
+stream(s), collecting operands on an internal stack until it finds a PDF
+operator. If that PDF operator's name exists in \type {operatortable}, then the
+associated function is executed. After the function has run (or when there is no
+function to execute) the internal operand stack is cleared in preparation for the
+next operator, and processing continues.
+
+The \type {scanner} argument to the processing functions is needed because it
+offers various methods to get the actual operands from the internal operand
+stack.
+
+A simple example of processing a PDF's document stream could look like this:
+
+\starttyping
+function Do (scanner, info)
+   local val       = scanner:pop()
+   local name      = val[2] -- val[1] == 'name'
+   local resources = info.resources
+   local xobject   = resources:lookup("XObject"):getDict():lookup(name)
+   print (info.space ..'Use XObject '.. name)
+   if xobject and xobject:isStream() then
+      local dict = xobject:getStream():getDict()
+      if dict then
+        local name = dict:lookup("Subtype")
+        if name:getName() == "Form" then
+          local newinfo =  {
+            space = info.space .. "  " ,
+            resources = dict:lookup("Resources"):getDict()
+          }
+          pdfscanner.scan(xobject, operatortable, newinfo)
+        end
+      end
+   end
+end
+
+operatortable = { Do = Do }
+
+doc      = epdf.open(arg[1])
+pagenum  = 1
+
+while pagenum <= doc:getNumPages() do
+   local page = doc:getCatalog():getPage(pagenum)
+   local info = {
+     space     = "  " ,
+     resources = page:getResourceDict()
+   }
+   print('Page ' .. pagenum)
+   pdfscanner.scan(page:getContents(), operatortable, info)
+   pagenum = pagenum + 1
+end
+\stoptyping
+
+This example iterates over all the actual content in the PDF, and prints out the
+found XObject names. While the code demonstrates quite some of the \type {epdf}
+functions, let's focus on the type \type {pdfscanner} specific code instead.
+
+From the bottom up, the line
+
+\starttyping
+   pdfscanner.scan(page:getContents(), operatortable, info)
+\stoptyping
+
+runs the scanner with the PDF page's top-level content.
+
+The third argument, \type {info}, contains two entries: \type {space} is used to
+indent the printed output, and \type {resources} is needed so that embedded \type
+{XForms} can find their own content.
+
+The second argument, \type {operatortable} defines a processing function for a
+single PDF operator, \type {Do}.
+
+The function \type {Do} prints the name of the current XObject, and then starts a
+new scanner for that object's content stream, under the condition that the
+XObject is in fact a \type {/Form}. That nested scanner is called with new \type
+{info} argument with an updated \type {space} value so that the indentation of
+the output nicely nests, and with an new \type {resources} field to help the next
+iteration down to properly process any other, embedded XObjects.
+
+Of course, this is not a very useful example in practise, but for the purpose of
+demonstrating \type {pdfscanner}, it is just long enough. It makes use of only
+one \type {scanner} method: \type {scanner:pop()}. That function pops the top
+operand of the internal stack, and returns a lua table where the object at index
+one is a string representing the type of the operand, and object two is its
+value.
+
+The list of possible operand types and associated lua value types is:
+
+\starttabulate[|lT|p|]
+\NC integer  \NC <number>  \NC \NR
+\NC real     \NC <number>  \NC \NR
+\NC boolean  \NC <boolean> \NC \NR
+\NC name     \NC <string>  \NC \NR
+\NC operator \NC <string>  \NC \NR
+\NC string   \NC <string>  \NC \NR
+\NC array    \NC <table>   \NC \NR
+\NC dict     \NC <table>   \NC \NR
+\stoptabulate
+
+In case of \type {integer} or \type {real}, the value is always a \LUA\ (floating
+point) number.
+
+In case of \type {name}, the leading slash is always stripped.
+
+In case of \type {string}, please bear in mind that PDF actually supports
+different types of strings (with different encodings) in different parts of the
+PDF document, so may need to reencode some of the results; \type {pdfscanner}
+always outputs the byte stream without reencoding anything. \type {pdfscanner}
+does not differentiate between literal strings and hexidecimal strings (the
+hexadecimal values are decoded), and it treats the stream data for inline images
+as a string that is the single operand for \type {EI}.
+
+In case of \type {array}, the table content is a list of \type {pop} return
+values.
+
+In case of \type {dict}, the table keys are PDF name strings and the values are
+\type {pop} return values.
+
+\blank
+
+There are few more methods defined that you can ask \type {scanner}:
+
+\starttabulate[|lT|p|]
+\NC pop       \NC as explained above \NC \NR
+\NC popNumber \NC return only the value of a \type {real} or \type {integer} \NC \NR
+\NC popName   \NC return only the value of a \type {name} \NC \NR
+\NC popString \NC return only the value of a \type {string} \NC \NR
+\NC popArray  \NC return only the value of a \type {array} \NC \NR
+\NC popDict   \NC return only the value of a \type {dict} \NC \NR
+\NC popBool   \NC return only the value of a \type {boolean} \NC \NR
+\NC done      \NC abort further processing of this \type {scan()} call \NC \NR
+\stoptabulate
+
+The \type {popXXX} are convenience functions, and come in handy when you know the
+type of the operands beforehand (which you usually do, in PDF). For example, the
+\type {Do} function could have used \type {local name = scanner:popName()}
+instead, because the single operand to the \type {Do} operator is always a PDF
+name object.
+
+The \type {done} function allows you to abort processing of a stream once you
+have learned everything you want to learn. This comes in handy while parsing
+\type {/ToUnicode}, because there usually is trailing garbage that you are not
+interested in. Without \type {done}, processing only end at the end of the
+stream, possibly wasting CPU cycles.
+
+\section{The \type {status} library}
+
+This contains a number of run|-|time configuration items that you may find useful
+in message reporting, as well as an iterator function that gets all of the names
+and values as a table.
+
+\startfunctioncall
+<table> info = status.list()
+\stopfunctioncall
+
+The keys in the table are the known items, the value is the current value. Almost
+all of the values in \type {status} are fetched through a metatable at run|-|time
+whenever they are accessed, so you cannot use \type {pairs} on \type {status},
+but you {\it can\/} use \type {pairs} on \type {info}, of course. If you do not
+need the full list, you can also ask for a single item by using its name as an
+index into \type {status}.
+
+The current list is:
+
+\starttabulate[|lT|p|]
+\NC \ssbf key          \NC \bf explanation \NC \NR
+\NC pdf_gone           \NC written \PDF\ bytes \NC \NR
+\NC pdf_ptr            \NC not yet written \PDF\ bytes \NC \NR
+\NC dvi_gone           \NC written \DVI\ bytes \NC \NR
+\NC dvi_ptr            \NC not yet written \DVI\ bytes \NC \NR
+\NC total_pages        \NC number of written pages \NC \NR
+\NC output_file_name   \NC name of the \PDF\ or \DVI\ file \NC \NR
+\NC log_name           \NC name of the log file \NC \NR
+\NC banner             \NC terminal display banner \NC \NR
+\NC var_used           \NC variable (one|-|word) memory in use \NC \NR
+\NC dyn_used           \NC token (multi|-|word) memory in use  \NC \NR
+\NC str_ptr            \NC number of strings \NC \NR
+\NC init_str_ptr       \NC number of \INITEX\ strings \NC \NR
+\NC max_strings        \NC maximum allowed strings \NC \NR
+\NC pool_ptr           \NC string pool index \NC \NR
+\NC init_pool_ptr      \NC \INITEX\ string pool index \NC \NR
+\NC pool_size          \NC current size allocated for string characters \NC \NR
+\NC node_mem_usage     \NC a string giving insight into currently used nodes \NC \NR
+\NC var_mem_max        \NC number of allocated words for nodes \NC \NR
+\NC fix_mem_max        \NC number of allocated words for tokens \NC \NR
+\NC fix_mem_end        \NC maximum number of used tokens \NC \NR
+\NC cs_count           \NC number of control sequences \NC \NR
+\NC hash_size          \NC size of hash \NC \NR
+\NC hash_extra         \NC extra allowed hash \NC \NR
+\NC font_ptr           \NC number of active fonts \NC \NR
+\NC max_in_stack       \NC max used input stack entries \NC \NR
+\NC max_nest_stack     \NC max used nesting stack entries \NC \NR
+\NC max_param_stack    \NC max used parameter stack entries \NC \NR
+\NC max_buf_stack      \NC max used buffer position \NC \NR
+\NC max_save_stack     \NC max used save stack entries \NC \NR
+\NC stack_size         \NC input stack size \NC \NR
+\NC nest_size          \NC nesting stack size \NC \NR
+\NC param_size         \NC parameter stack size \NC \NR
+\NC buf_size           \NC current allocated size of the line buffer \NC \NR
+\NC save_size          \NC save stack size \NC \NR
+\NC obj_ptr            \NC max \PDF\ object pointer \NC \NR
+\NC obj_tab_size       \NC \PDF\ object table size \NC \NR
+\NC pdf_os_cntr        \NC max \PDF\ object stream pointer \NC \NR
+\NC pdf_os_objidx      \NC \PDF\ object stream index \NC \NR
+\NC pdf_dest_names_ptr \NC max \PDF\ destination pointer \NC \NR
+\NC dest_names_size    \NC \PDF\ destination table size \NC \NR
+\NC pdf_mem_ptr        \NC max \PDF\ memory used \NC \NR
+\NC pdf_mem_size       \NC \PDF\ memory size \NC \NR
+\NC largest_used_mark  \NC max referenced marks class \NC \NR
+\NC filename           \NC name of the current input file \NC \NR
+\NC inputid            \NC numeric id of the current input \NC \NR
+\NC linenumber         \NC location in the current input file \NC \NR
+\NC lasterrorstring    \NC last error string\NC \NR
+\NC luabytecodes       \NC number of active \LUA\ bytecode registers \NC \NR
+\NC luabytecode_bytes  \NC number of bytes in \LUA\ bytecode registers \NC \NR
+\NC luastate_bytes     \NC number of bytes in use by \LUA\ interpreters \NC \NR
+\NC output_active      \NC \type {true} if the \type {\output} routine is active \NC \NR
+\NC callbacks          \NC total number of executed callbacks so far \NC \NR
+\NC indirect_callbacks \NC number of those that were themselves
+                           a result of other callbacks (e.g. file readers) \NC \NR
+\NC luatex_svn         \NC the luatex repository id  \NC \NR
+\NC luatex_version     \NC the luatex version number \NC \NR
+\NC luatex_revision    \NC the luatex revision string \NC \NR
+\NC ini_version        \NC \type {true} if this is an \INITEX\ run \NC \NR
+\stoptabulate
+
+\section{The \type {tex} library}
+
+The \type {tex} table contains a large list of virtual internal \TEX\
+parameters that are partially writable.
+
+The designation \quote {virtual} means that these items are not properly defined
+in \LUA, but are only front\-ends that are handled by a metatable that operates
+on the actual \TEX\ values. As a result, most of the \LUA\ table operators (like
+\type {pairs} and \type {#}) do not work on such items.
+
+At the moment, it is possible to access almost every parameter that has these
+characteristics:
+
+\startitemize[packed]
+\item You can use it after \type {\the}
+\item It is a single token.
+\item Some special others, see the list below
+\stopitemize
+
+This excludes parameters that need extra arguments, like \type {\the\scriptfont}.
+
+The subset comprising simple integer and dimension registers are
+writable as well as readable (stuff like \type {\tracingcommands} and
+\type {\parindent}).
+
+\subsection{Internal parameter values}
+
+For all the parameters in this section, it is possible to access them directly
+using their names as index in the \type {tex} table, or by using one of the
+functions \type {tex.get()} and \type {tex.set()}.
+
+The exact parameters and return values differ depending on the actual parameter,
+and so does whether \type {tex.set} has any effect. For the parameters that {\it
+can\/} be set, it is possible to use \type {global} as the first argument to
+\type {tex.set}; this makes the assignment global instead of local.
+
+\startfunctioncall
+tex.set (<string> n, ...)
+tex.set ('global', <string> n, ...)
+... = tex.get (<string> n)
+\stopfunctioncall
+
+\subsubsection{Integer parameters}
+
+The integer parameters accept and return \LUA\ numbers.
+
+Read|-|write:
+
+\starttwocolumns
+\starttyping
+tex.adjdemerits
+tex.binoppenalty
+tex.brokenpenalty
+tex.catcodetable
+tex.clubpenalty
+tex.day
+tex.defaulthyphenchar
+tex.defaultskewchar
+tex.delimiterfactor
+tex.displaywidowpenalty
+tex.doublehyphendemerits
+tex.endlinechar
+tex.errorcontextlines
+tex.escapechar
+tex.exhyphenpenalty
+tex.fam
+tex.finalhyphendemerits
+tex.floatingpenalty
+tex.globaldefs
+tex.hangafter
+tex.hbadness
+tex.holdinginserts
+tex.hyphenpenalty
+tex.interlinepenalty
+tex.language
+tex.lastlinefit
+tex.lefthyphenmin
+tex.linepenalty
+tex.localbrokenpenalty
+tex.localinterlinepenalty
+tex.looseness
+tex.mag
+tex.maxdeadcycles
+tex.month
+tex.newlinechar
+tex.outputpenalty
+tex.pausing
+tex.pdfadjustspacing
+tex.pdfcompresslevel
+tex.pdfdecimaldigits
+tex.pdfgamma
+tex.pdfgentounicode
+tex.pdfimageapplygamma
+tex.pdfimagegamma
+tex.pdfimagehicolor
+tex.pdfimageresolution
+tex.pdfinclusionerrorlevel
+tex.pdfminorversion
+tex.pdfobjcompresslevel
+tex.pdfoutput
+tex.pdfpagebox
+tex.pdfpkresolution
+tex.pdfprotrudechars
+tex.pdftracingfonts
+tex.pdfuniqueresname
+tex.postdisplaypenalty
+tex.predisplaydirection
+tex.predisplaypenalty
+tex.pretolerance
+tex.relpenalty
+tex.righthyphenmin
+tex.savinghyphcodes
+tex.savingvdiscards
+tex.showboxbreadth
+tex.showboxdepth
+tex.time
+tex.tolerance
+tex.tracingassigns
+tex.tracingcommands
+tex.tracinggroups
+tex.tracingifs
+tex.tracinglostchars
+tex.tracingmacros
+tex.tracingnesting
+tex.tracingonline
+tex.tracingoutput
+tex.tracingpages
+tex.tracingparagraphs
+tex.tracingrestores
+tex.tracingscantokens
+tex.tracingstats
+tex.uchyph
+tex.vbadness
+tex.widowpenalty
+tex.year
+\stoptyping
+\stoptwocolumns
+
+Read|-|only:
+
+\startthreecolumns
+\starttyping
+tex.deadcycles
+tex.insertpenalties
+tex.parshape
+tex.prevgraf
+tex.spacefactor
+\stoptyping
+\stopthreecolumns
+
+\subsubsection{Dimension parameters}
+
+The dimension parameters accept \LUA\ numbers (signifying scaled points) or
+strings (with included dimension). The result is always a number in scaled
+points.
+
+Read|-|write:
+
+\startthreecolumns
+\starttyping
+tex.boxmaxdepth
+tex.delimitershortfall
+tex.displayindent
+tex.displaywidth
+tex.emergencystretch
+tex.hangindent
+tex.hfuzz
+tex.hoffset
+tex.hsize
+tex.lineskiplimit
+tex.mathsurround
+tex.maxdepth
+tex.nulldelimiterspace
+tex.overfullrule
+tex.pagebottomoffset
+tex.pageheight
+tex.pageleftoffset
+tex.pagerightoffset
+tex.pagetopoffset
+tex.pagewidth
+tex.parindent
+tex.pdfdestmargin
+tex.pdfhorigin
+tex.pdflinkmargin
+tex.pdfpageheight
+tex.pdfpagewidth
+tex.pdfpxdimen
+tex.pdfthreadmargin
+tex.pdfvorigin
+tex.predisplaysize
+tex.scriptspace
+tex.splitmaxdepth
+tex.vfuzz
+tex.voffset
+tex.vsize
+\stoptyping
+\stopthreecolumns
+
+Read|-|only:
+
+\startthreecolumns
+\starttyping
+tex.pagedepth
+tex.pagefilllstretch
+tex.pagefillstretch
+tex.pagefilstretch
+tex.pagegoal
+tex.pageshrink
+tex.pagestretch
+tex.pagetotal
+tex.prevdepth
+\stoptyping
+\stopthreecolumns
+
+\subsubsection{Direction parameters}
+
+The direction parameters are read|-|only and return a \LUA\ string.
+
+\startthreecolumns
+\starttyping
+tex.bodydir
+tex.mathdir
+tex.pagedir
+tex.pardir
+tex.textdir
+\stoptyping
+\stopthreecolumns
+
+\subsubsection{Glue parameters}
+
+The glue parameters accept and return a userdata object that represents a \type
+{glue_spec} node.
+
+\startthreecolumns
+\starttyping
+tex.abovedisplayshortskip
+tex.abovedisplayskip
+tex.baselineskip
+tex.belowdisplayshortskip
+tex.belowdisplayskip
+tex.leftskip
+tex.lineskip
+tex.parfillskip
+tex.parskip
+tex.rightskip
+tex.spaceskip
+tex.splittopskip
+tex.tabskip
+tex.topskip
+tex.xspaceskip
+\stoptyping
+\stopthreecolumns
+
+\subsubsection{Muglue parameters}
+
+All muglue parameters are to be used read|-|only and return a \LUA\ string.
+
+\startthreecolumns
+\starttyping
+tex.medmuskip
+tex.thickmuskip
+tex.thinmuskip
+\stoptyping
+\stopthreecolumns
+
+\subsubsection{Tokenlist parameters}
+
+The tokenlist parameters accept and return \LUA\ strings. \LUA\ strings are
+converted to and from token lists using \type {\the} \type {\toks} style expansion:
+all category codes are either space (10) or other (12). It follows that assigning
+to some of these, like \quote {tex.output}, is actually useless, but it feels bad
+to make exceptions in view of a coming extension that will accept full|-|blown
+token strings.
+
+\startthreecolumns
+\starttyping
+tex.errhelp
+tex.everycr
+tex.everydisplay
+tex.everyeof
+tex.everyhbox
+tex.everyjob
+tex.everymath
+tex.everypar
+tex.everyvbox
+tex.output
+tex.pdfpageattr
+tex.pdfpageresources
+tex.pdfpagesattr
+tex.pdfpkmode
+\stoptyping
+\stopthreecolumns
+
+\subsection{Convert commands}
+
+All \quote {convert} commands are read|-|only and return a \LUA\ string. The
+supported commands at this moment are:
+
+\starttwocolumns
+\starttyping
+tex.eTeXVersion
+tex.eTeXrevision
+tex.formatname
+tex.jobname
+tex.luatexbanner
+tex.luatexrevision
+tex.pdfnormaldeviate
+tex.fontname(number)
+tex.pdffontname(number)
+tex.pdffontobjnum(number)
+tex.pdffontsize(number)
+tex.uniformdeviate(number)
+tex.number(number)
+tex.romannumeral(number)
+tex.pdfpageref(number)
+tex.pdfxformname(number)
+tex.fontidentifier(number)
+\stoptyping
+\stoptwocolumns
+
+If you are wondering why this list looks haphazard; these are all the cases of
+the \quote {convert} internal command that do not require an argument, as well as
+the ones that require only a simple numeric value.
+
+The special (lua-only) case of \type {tex.fontidentifier} returns the \type
+{csname} string that matches a font id number (if there is one).
+
+if these are really needed in a macro package.
+
+\subsection{Last item commands}
+
+All \quote {last item} commands are read|-|only and return a number.
+
+The supported commands at this moment are:
+
+\startthreecolumns
+\starttyping
+tex.lastpenalty
+tex.lastkern
+tex.lastskip
+tex.lastnodetype
+tex.inputlineno
+tex.pdflastobj
+tex.pdflastxform
+tex.pdflastximage
+tex.pdflastximagepages
+tex.pdflastannot
+tex.pdflastxpos
+tex.pdflastypos
+tex.pdfrandomseed
+tex.pdflastlink
+tex.luatexversion
+tex.eTeXminorversion
+tex.eTeXversion
+tex.currentgrouplevel
+tex.currentgrouptype
+tex.currentiflevel
+tex.currentiftype
+tex.currentifbranch
+tex.pdflastximagecolordepth
+\stoptyping
+\stopthreecolumns
+
+\subsection{Attribute, count, dimension, skip and token registers}
+
+\TEX's attributes (\type {\attribute}), counters (\type {\count}), dimensions (\type
+{\dimen}), skips (\type {\skip}) and token (\type {\toks}) registers can be accessed
+and written to using two times five virtual sub|-|tables of the \type {tex}
+table:
+
+\startthreecolumns
+\starttyping
+tex.attribute
+tex.count
+tex.dimen
+tex.skip
+tex.toks
+\stoptyping
+\stopthreecolumns
+
+It is possible to use the names of relevant \type {\attributedef}, \type {\countdef},
+\type {\dimendef}, \type {\skipdef}, or \type {\toksdef} control sequences as indices
+to these tables:
+
+\starttyping
+tex.count.scratchcounter = 0
+enormous = tex.dimen['maxdimen']
+\stoptyping
+
+In this case, \LUATEX\ looks up the value for you on the fly. You have to use a
+valid \type {\countdef} (or \type {\attributedef}, or \type {\dimendef}, or \type
+{\skipdef}, or \type {\toksdef}), anything else will generate an error (the intent
+is to eventually also allow \type {<chardef tokens>} and even macros that expand
+into a number).
+
+The attribute and count registers accept and return \LUA\ numbers.
+
+The dimension registers accept \LUA\ numbers (in scaled points) or strings (with
+an included absolute dimension; \type {em} and \type {ex} and \type {px} are
+forbidden). The result is always a number in scaled points.
+
+The token registers accept and return \LUA\ strings. \LUA\ strings are converted
+to and from token lists using \type {\the} \type {\toks} style expansion: all
+category codes are either space (10) or other (12).
+
+The skip registers accept and return \type {glue_spec} userdata node objects (see
+the description of the node interface elsewhere in this manual).
+
+As an alternative to array addressing, there are also accessor functions defined
+for all cases, for example, here is the set of possibilities for \type {\skip}
+registers:
+
+\startfunctioncall
+tex.setskip (<number> n, <node> s)
+tex.setskip (<string> s, <node> s)
+tex.setskip ('global',<number> n, <node> s)
+tex.setskip ('global',<string> s, <node> s)
+<node> s = tex.getskip (<number> n)
+<node> s = tex.getskip (<string> s)
+\stopfunctioncall
+
+In the function-based interface, it is possible to define values globally by
+using the string \type {global} as the first function argument.
+
+\subsection{Character code registers}
+
+\TEX's character code tables (\type {\lccode}, \type {\uccode}, \type {\sfcode}, \type
+{\catcode}, \type {\mathcode}, \type {\delcode}) can be accessed and written to using
+six virtual subtables of the \type {tex} table
+
+\startthreecolumns
+\starttyping
+tex.lccode
+tex.uccode
+tex.sfcode
+tex.catcode
+tex.mathcode
+tex.delcode
+\stoptyping
+\stopthreecolumns
+
+The function call interfaces are roughly as above, but there are a few twists.
+\type {sfcode}s are the simple ones:
+
+\startfunctioncall
+tex.setsfcode (<number> n, <number> s)
+tex.setsfcode ('global', <number> n, <number> s)
+<number> s = tex.getsfcode (<number> n)
+\stopfunctioncall
+
+The function call interface for \type {lccode} and \type {uccode} additionally
+allows you to set the associated sibling at the same time:
+
+\startfunctioncall
+tex.setlccode (['global'], <number> n, <number> lc)
+tex.setlccode (['global'], <number> n, <number> lc, <number> uc)
+<number> lc = tex.getlccode (<number> n)
+tex.setuccode (['global'], <number> n, <number> uc)
+tex.setuccode (['global'], <number> n, <number> uc, <number> lc)
+<number> uc = tex.getuccode (<number> n)
+\stopfunctioncall
+
+The function call interface for \type {catcode} also allows you to specify a
+category table to use on assignment or on query (default in both cases is the
+current one):
+
+\startfunctioncall
+tex.setcatcode (['global'], <number> n, <number> c)
+tex.setcatcode (['global'], <number> cattable, <number> n, <number> c)
+<number> lc = tex.getcatcode (<number> n)
+<number> lc = tex.getcatcode (<number> cattable, <number> n)
+\stopfunctioncall
+
+The interfaces for \type {delcode} and \type {mathcode} use small array tables to
+set and retrieve values:
+
+\startfunctioncall
+tex.setmathcode (['global'], <number> n, <table> mval )
+<table> mval = tex.getmathcode (<number> n)
+tex.setdelcode (['global'], <number> n, <table> dval )
+<table> dval = tex.getdelcode (<number> n)
+\stopfunctioncall
+
+Where the table for \type {mathcode} is an array of 3 numbers, like this:
+
+\starttyping
+{<number> mathclass, <number> family, <number> character}
+\stoptyping
+
+And the table for \type {delcode} is an array with 4 numbers, like this:
+
+\starttyping
+{<number> small_fam, <number> small_char, <number> large_fam, <number> large_char}
+\stoptyping
+
+Normally, the third and fourth values in a delimiter code assignment will be zero
+according to \type {\Udelcode} usage, but the returned table can have values there
+(if the delimiter code was set using \type {\delcode}, for example). Unset \type
+{delcode}'s can be recognized because \type {dval[1]} is $-1$.
+
+\subsection{Box registers}
+
+It is possible to set and query actual boxes, using the node interface as defined
+in the \type {node} library:
+
+\starttyping
+tex.box
+\stoptyping
+
+for array access, or
+
+\starttyping
+tex.setbox(<number> n, <node> s)
+tex.setbox(<string> cs, <node> s)
+tex.setbox('global', <number> n, <node> s)
+tex.setbox('global', <string> cs, <node> s)
+<node> n = tex.getbox(<number> n)
+<node> n = tex.getbox(<string> cs)
+\stoptyping
+
+for function|-|based access. In the function-based interface, it is possible to
+define values globally by using the string \type {global} as the first function
+argument.
+
+Be warned that an assignment like
+
+\starttyping
+tex.box[0] = tex.box[2]
+\stoptyping
+
+does not copy the node list, it just duplicates a node pointer. If \type {\box2}
+will be cleared by \TEX\ commands later on, the contents of \type {\box0} becomes
+invalid as well. To prevent this from happening, always use \type
+{node.copy_list()} unless you are assigning to a temporary variable:
+
+\starttyping
+tex.box[0] = node.copy_list(tex.box[2])
+\stoptyping
+
+\subsection{Math parameters}
+
+It is possible to set and query the internal math parameters using:
+
+\startfunctioncall
+tex.setmath(<string> n, <string> t, <number> n)
+tex.setmath('global', <string> n, <string> t, <number> n)
+<number> n = tex.getmath(<string> n, <string> t)
+\stopfunctioncall
+
+As before an optional first parameter \type {global} indicates a global
+assignment.
+
+The first string is the parameter name minus the leading \quote {Umath}, and the
+second string is the style name minus the trailing \quote {style}.
+
+Just to be complete, the values for the math parameter name are:
+
+\starttyping
+quad                axis                operatorsize
+overbarkern         overbarrule         overbarvgap
+underbarkern        underbarrule        underbarvgap
+radicalkern         radicalrule         radicalvgap
+radicaldegreebefore radicaldegreeafter  radicaldegreeraise
+stackvgap           stacknumup          stackdenomdown
+fractionrule        fractionnumvgap     fractionnumup
+fractiondenomvgap   fractiondenomdown   fractiondelsize
+limitabovevgap      limitabovebgap      limitabovekern
+limitbelowvgap      limitbelowbgap      limitbelowkern
+underdelimitervgap  underdelimiterbgap
+overdelimitervgap   overdelimiterbgap
+subshiftdrop        supshiftdrop        subshiftdown
+subsupshiftdown     subtopmax           supshiftup
+supbottommin        supsubbottommax     subsupvgap
+spaceafterscript    connectoroverlapmin
+ordordspacing       ordopspacing        ordbinspacing     ordrelspacing
+ordopenspacing      ordclosespacing     ordpunctspacing   ordinnerspacing
+opordspacing        opopspacing         opbinspacing      oprelspacing
+opopenspacing       opclosespacing      oppunctspacing    opinnerspacing
+binordspacing       binopspacing        binbinspacing     binrelspacing
+binopenspacing      binclosespacing     binpunctspacing   bininnerspacing
+relordspacing       relopspacing        relbinspacing     relrelspacing
+relopenspacing      relclosespacing     relpunctspacing   relinnerspacing
+openordspacing      openopspacing       openbinspacing    openrelspacing
+openopenspacing     openclosespacing    openpunctspacing  openinnerspacing
+closeordspacing     closeopspacing      closebinspacing   closerelspacing
+closeopenspacing    closeclosespacing   closepunctspacing closeinnerspacing
+punctordspacing     punctopspacing      punctbinspacing   punctrelspacing
+punctopenspacing    punctclosespacing   punctpunctspacing punctinnerspacing
+innerordspacing     inneropspacing      innerbinspacing   innerrelspacing
+inneropenspacing    innerclosespacing   innerpunctspacing innerinnerspacing
+\stoptyping
+
+The values for the style parameter name are:
+
+\starttyping
+display       crampeddisplay
+text          crampedtext
+script        crampedscript
+scriptscript  crampedscriptscript
+\stoptyping
+
+\subsection{Special list heads}
+
+The virtual table \type {tex.lists} contains the set of internal registers that
+keep track of building page lists.
+
+\starttabulate[|lT|p|]
+\NC \bf field       \NC \bf description \NC \NR
+\NC page_ins_head   \NC circular list of pending insertions \NC \NR
+\NC contrib_head    \NC the recent contributions \NC \NR
+\NC page_head       \NC the current page content \NC \NR
+%NC temp_head       \NC \NC \NR
+\NC hold_head       \NC used for held-over items for next page \NC \NR
+\NC adjust_head     \NC head of the current \type {\vadjust} list \NC \NR
+\NC pre_adjust_head \NC head of the current \type {\vadjust pre} list \NC \NR
+%NC align_head      \NC \NC \NR
+\stoptabulate
+
+\subsection{Semantic nest levels}
+
+The virtual table \type {tex.nest} contains the currently active
+semantic nesting state. It has two main parts: a zero-based array of userdata for
+the semantic nest itself, and the numerical value \type {tex.nest.ptr}, which
+gives the highest available index. Neither the array items in \type {tex.nest[]}
+nor \type {tex.nest.ptr} can be assigned to (as this would confuse the
+typesetting engine beyond repair), but you can assign to the individual values
+inside the array items, e.g.\ \type {tex.nest[tex.nest.ptr].prevdepth}.
+
+\type {tex.nest[tex.nest.ptr]} is the current nest state, \type {tex.nest[0]} the
+outermost (main vertical list) level.
+
+The known fields are:
+
+\starttabulate[|lT|l|l|p|]
+\NC \ssbf key   \NC \bf type \NC \bf modes \NC \bf explanation \NC \NR
+\NC mode        \NC number   \NC all       \NC The current mode. This is a number representing the
+                                               main mode at this level:\crlf
+                                               \type {0} == no mode (this happens during \type {\write})\crlf
+                                               \type {1} == vertical,\crlf
+                                               \type {127} = horizontal,\crlf
+                                               \type {253} = display math.\crlf
+                                               \type {-1} == internal vertical,\crlf
+                                               \type {-127} = restricted horizontal,\crlf
+                                               \type {-253} = inline math. \NC \NR
+\NC modeline    \NC number   \NC all       \NC source input line where this mode was entered in,
+                                               negative inside the output routine \NC \NR
+\NC head        \NC node     \NC all       \NC the head of the current list \NC \NR
+\NC tail        \NC node     \NC all       \NC the tail of the current list \NC \NR
+\NC prevgraf    \NC number   \NC vmode     \NC number of lines in the previous paragraph \NC \NR
+\NC prevdepth   \NC number   \NC vmode     \NC depth of the previous paragraph (equal to \type {\pdfignoreddimen}
+                                               when it is to be ignored) \NC \NR
+\NC spacefactor \NC number   \NC hmode     \NC the current space factor \NC \NR
+\NC dirs        \NC node     \NC hmode     \NC used for temporary storage by the line break algorithm\NC \NR
+\NC noad        \NC node     \NC mmode     \NC used for temporary storage of a pending fraction numerator,
+                                               for \type {\over} etc. \NC \NR
+\NC delimptr    \NC node     \NC mmode     \NC used for temporary storage of the previous math delimiter,
+                                               for \type {\middle} \NC \NR
+\NC mathdir     \NC boolean  \NC mmode     \NC true when during math processing the \type {\mathdir} is not
+                                               the same as the surrounding \type {\textdir} \NC \NR
+\NC mathstyle   \NC number   \NC mmode     \NC the current \type {\mathstyle} \NC \NR
+\stoptabulate
+
+\subsection[sec:luaprint]{Print functions}
+
+The \type {tex} table also contains the three print functions that are the
+major interface from \LUA\ scripting to \TEX.
+
+The arguments to these three functions are all stored in an in|-|memory virtual
+file that is fed to the \TEX\ scanner as the result of the expansion of
+\type {\directlua}.
+
+The total amount of returnable text from a \type {\directlua} command is only
+limited by available system \RAM. However, each separate printed string has to
+fit completely in \TEX's input buffer.
+
+The result of using these functions from inside callbacks is undefined
+at the moment.
+
+\subsubsection{\type {tex.print}}
+
+\startfunctioncall
+tex.print(<string> s, ...)
+tex.print(<number> n, <string> s, ...)
+tex.print(<table> t)
+tex.print(<number> n, <table> t)
+\stopfunctioncall
+
+Each string argument is treated by \TEX\ as a separate input line. If there is a
+table argument instead of a list of strings, this has to be a consecutive array
+of strings to print (the first non-string value will stop the printing process).
+
+The optional parameter can be used to print the strings using the catcode regime
+defined by \type {\catcodetable}~\type {n}. If \type {n} is $-1$, the currently
+active catcode regime is used. If \type {n} is $-2$, the resulting catcodes are
+the result of \type {\the} \type {\toks}: all category codes are 12 (other) except for
+the space character, that has category code 10 (space). Otherwise, if \type {n}
+is not a valid catcode table, then it is ignored, and the currently active
+catcode regime is used instead.
+
+The very last string of the very last \type {tex.print()} command in a \type
+{\directlua} will not have the \type {\endlinechar} appended, all others do.
+
+\subsubsection{\type {tex.sprint}}
+
+\startfunctioncall
+tex.sprint(<string> s, ...)
+tex.sprint(<number> n, <string> s, ...)
+tex.sprint(<table> t)
+tex.sprint(<number> n, <table> t)
+\stopfunctioncall
+
+Each string argument is treated by \TEX\ as a special kind of input line that
+makes it suitable for use as a partial line input mechanism:
+
+\startitemize[packed]
+\startitem
+    \TEX\ does not switch to the \quote {new line} state, so that leading spaces
+    are not ignored.
+\stopitem
+\startitem
+    No \type {\endlinechar} is inserted.
+\stopitem
+\startitem
+    Trailing spaces are not removed.
+
+    Note that this does not prevent \TEX\ itself from eating spaces as result of
+    interpreting the line. For example, in
+
+\starttyping
+before\directlua{tex.sprint("\\relax")tex.sprint(" inbetween")}after
+\stoptyping
+    the space before \type {inbetween} will be gobbled as a result of the \quote
+    {normal} scanning of \type {\relax}.
+\stopitem
+\stopitemize
+
+If there is a table argument instead of a list of strings, this has to
+be a consecutive array of strings to print (the first non-string value
+will stop the printing process).
+
+The optional argument sets the catcode regime, as with \type {tex.print()}.
+
+\subsubsection{\type {tex.tprint}}
+
+\startfunctioncall
+tex.tprint({<number> n, <string> s, ...}, {...})
+\stopfunctioncall
+
+This function is basically a shortcut for repeated calls to \type
+{tex.sprint(<number> n, <string> s, ...)}, once for each of the supplied argument
+tables.
+
+\subsubsection{\type {tex.write}}
+
+\startfunctioncall
+tex.write(<string> s, ...)
+tex.write(<table> t)
+\stopfunctioncall
+
+Each string argument is treated by \TEX\ as a special kind of input line that
+makes it suitable for use as a quick way to dump information:
+
+\startitemize
+\item All catcodes on that line are either \quote{space} (for '~') or
+     \quote{character} (for all others).
+\item There is no \type {\endlinechar} appended.
+\stopitemize
+
+If there is a table argument instead of a list of strings, this has to be a
+consecutive array of strings to print (the first non-string value will stop the
+printing process).
+
+\subsection{Helper functions}
+
+\subsubsection{\type {tex.round}}
+
+\startfunctioncall
+<number> n = tex.round(<number> o)
+\stopfunctioncall
+
+Rounds \LUA\ number \type {o}, and returns a number that is in the range of a
+valid \TEX\ register value. If the number starts out of range, it generates a
+\quote {number to big} error as well.
+
+\subsubsection{\type {tex.scale}}
+
+\startfunctioncall
+<number> n = tex.scale(<number> o, <number> delta)
+<table> n = tex.scale(table o, <number> delta)
+\stopfunctioncall
+
+Multiplies the \LUA\ numbers \type {o} and \type {delta}, and returns a rounded
+number that is in the range of a valid \TEX\ register value. In the table
+version, it creates a copy of the table with all numeric top||level values scaled
+in that manner. If the multiplied number(s) are of range, it generates
+\quote{number to big} error(s) as well.
+
+Note: the precision of the output of this function will depend on your computer's
+architecture and operating system, so use with care! An interface to \LUATEX's
+internal, 100\% portable scale function will be added at a later date.
+
+\subsubsection{\type {tex.sp}}
+
+\startfunctioncall
+<number> n = tex.sp(<number> o)
+<number> n = tex.sp(<string> s)
+\stopfunctioncall
+
+Converts the number \type {o} or a string \type {s} that represents an explicit
+dimension into an integer number of scaled points.
+
+For parsing the string, the same scanning and conversion rules are used that
+\LUATEX\ would use if it was scanning a dimension specifier in its \TEX|-|like
+input language (this includes generating errors for bad values), expect for the
+following:
+
+\startitemize[n]
+\startitem
+    only explicit values are allowed, control sequences are not handled
+\stopitem
+\startitem
+    infinite dimension units (\type {fil...}) are forbidden
+\stopitem
+\startitem
+    \type {mu} units do not generate an error (but may not be useful either)
+\stopitem
+\stopitemize
+
+\subsubsection{\type {tex.definefont}}
+
+\startfunctioncall
+tex.definefont(<string> csname, <number> fontid)
+tex.definefont(<boolean> global, <string> csname, <number> fontid)
+\stopfunctioncall
+
+Associates \type {csname} with the internal font number \type {fontid}. The
+definition is global if (and only if) \type {global} is specified and true (the
+setting of \type {globaldefs} is not taken into account).
+
+\subsubsection{\type {tex.error}}
+
+\startfunctioncall
+tex.error(<string> s)
+tex.error(<string> s, <table> help)
+\stopfunctioncall
+
+This creates an error somewhat like the combination of \type {\errhelp} and \type
+{\errmessage} would. During this error, deletions are disabled.
+
+The array part of the \type {help} table has to contain strings, one for each
+line of error help.
+
+\subsubsection{\type {tex.hashtokens}}
+
+\startfunctioncall
+for i,v in pairs (tex.hashtokens()) do ... end
+\stopfunctioncall
+
+Returns a name and token table pair (see~\in {section} [luatokens] about token
+tables) iterator for every non-zero entry in the hash table. This can be useful
+for debugging, but note that this also reports control sequences that may be
+unreachable at this moment due to local redefinitions: it is strictly a dump of
+the hash table.
+
+\subsection[luaprimitives]{Functions for dealing with primitives }
+
+\subsubsection{\type {tex.enableprimitives}}
+
+\startfunctioncall
+tex.enableprimitives(<string> prefix, <table> primitive names)
+\stopfunctioncall
+
+This function accepts a prefix string and an array of primitive names.
+
+For each combination of \quote {prefix} and \quote {name}, the \type
+{tex.enableprimitives} first verifies that \quote {name} is an actual primitive
+(it must be returned by one of the \type {tex.extraprimitives()} calls explained
+below, or part of \TEX82, or \type {\directlua}). If it is not, \type
+{tex.enableprimitives} does nothing and skips to the next pair.
+
+But if it is, then it will construct a csname variable by concatenating the
+\quote {prefix} and \quote {name}, unless the \quote {prefix} is already the
+actual prefix of \quote {name}. In the latter case, it will discard the \quote
+{prefix}, and just use \quote {name}.
+
+Then it will check for the existence of the constructed csname. If the csname is
+currently undefined (note: that is not the same as \type {\relax}), it will
+globally define the csname to have the meaning: run code belonging to the
+primitive \quote {name}. If for some reason the csname is already defined, it
+does nothing and tries the next pair.
+
+An example:
+
+\starttyping
+  tex.enableprimitives('LuaTeX', {'formatname'})
+\stoptyping
+
+will define \type {\LuaTeXformatname} with the same intrinsic meaning as the
+documented primitive \type {\formatname}, provided that the control sequences \type
+{\LuaTeXformatname} is currently undefined.
+
+Second example:
+
+\starttyping
+  tex.enableprimitives('Omega',tex.extraprimitives ('omega'))
+\stoptyping
+
+will define a whole series of csnames like \type {\Omegatextdir}, \type
+{\Omegapardir}, etc., but it will stick with \type {\OmegaVersion} instead of
+creating the doubly-prefixed \type {\OmegaOmegaVersion}.
+
+When \LUATEX\ is run with \type {--ini} only the \TEX82 primitives and \type
+{\directlua} are available, so no extra primitives {\bf at all}.
+
+If you want to have all the new functionality available using their default
+names, as it is now, you will have to add
+
+\starttyping
+  \ifx\directlua\undefined \else
+     \directlua {tex.enableprimitives('',tex.extraprimitives ())}
+  \fi
+\stoptyping
+
+near the beginning of your format generation file. Or you can choose different
+prefixes for different subsets, as you see fit.
+
+Calling some form of \type {tex.enableprimitives()} is highly important though,
+because if you do not, you will end up with a \TEX82-lookalike that can run \LUA\
+code but not do much else. The defined csnames are (of course) saved in the
+format and will be available at runtime.
+
+\subsubsection{\type {tex.extraprimitives}}
+
+\startfunctioncall
+<table> t = tex.extraprimitives(<string> s, ...)
+\stopfunctioncall
+
+This function returns a list of the primitives that originate from the engine(s)
+given by the requested string value(s). The possible values and their (current)
+return values are:
+
+\startluacode
+function document.showprimitives(tag)
+    for k, v in table.sortedpairs(tex.extraprimitives(tag)) do
+        if v == ' ' then
+            v = '\\normalcontrolspace'
+        end
+        context.type(v)
+        context.space()
+    end
+end
+\stopluacode
+
+\starttabulate[|l|pl|]
+\NC \bf name\NC \bf values \NC \NR
+\NC tex     \NC \ctxlua{document.showprimitives('tex')    } \NC \NR
+\NC core    \NC \ctxlua{document.showprimitives('core')   } \NC \NR
+\NC etex    \NC \ctxlua{document.showprimitives('etex')   } \NC \NR
+\NC pdftex  \NC \ctxlua{document.showprimitives('pdftex') } \NC \NR
+\NC luatex  \NC \ctxlua{document.showprimitives('luatex') } \NC \NR
+\NC umath   \NC \ctxlua{document.showprimitives('umath') }  \NC \NR
+\stoptabulate
+
+Note that \type {'luatex'} does not contain \type {directlua}, as that
+isconsidered to be a core primitive, along with all the \TEX82 primitives, so it
+is part of the list that is returned from \type {'core'}.
+
+\type {'umath'} is a subset of \type {'luatex'} that covers the Unicode math
+primitives as it might be desired to handle the prefixing of that subset
+differently.
+
+Running \type {tex.extraprimitives()} will give you the complete list of
+primitives \type {-ini} startup. It is exactly equivalent to \type
+{tex.extraprimitives('etex', 'pdftex' and 'luatex')}.
+
+\subsubsection{\type {tex.primitives}}
+
+\startfunctioncall
+<table> t = tex.primitives()
+\stopfunctioncall
+
+This function returns a hash table listing all primitives that \LUATEX\ knows
+about. The keys in the hash are primitives names, the values are tables
+representing tokens (see~\in{section }[luatokens]). The third value is always
+zero.
+
+\subsection{Core functionality interfaces}
+
+\subsubsection{\type {tex.badness}}
+
+\startfunctioncall
+<number> b = tex.badness(<number> t, <number> s)
+\stopfunctioncall
+
+This helper function is useful during linebreak calculations. \type {t} and \type
+{s} are scaled values; the function returns the badness for when total \type {t}
+is supposed to be made from amounts that sum to \type {s}. The returned number is
+a reasonable approximation of $100(t/s)^3$;
+
+\subsubsection{\type {tex.linebreak}}
+
+\startfunctioncall
+local <node> nodelist, <table> info =
+       tex.linebreak(<node> listhead, <table> parameters)
+\stopfunctioncall
+
+The understood parameters are as follows:
+
+\starttabulate[|l|l|p|]
+\NC \bf name                 \NC \bf type        \NC \bf description \NC \NR
+\NC pardir                   \NC string          \NC \NC \NR
+\NC pretolerance             \NC number          \NC \NC \NR
+\NC tracingparagraphs        \NC number          \NC \NC \NR
+\NC tolerance                \NC number          \NC \NC \NR
+\NC looseness                \NC number          \NC \NC \NR
+\NC hyphenpenalty            \NC number          \NC \NC \NR
+\NC exhyphenpenalty          \NC number          \NC \NC \NR
+\NC pdfadjustspacing         \NC number          \NC \NC \NR
+\NC adjdemerits              \NC number          \NC \NC \NR
+\NC pdfprotrudechars         \NC number          \NC \NC \NR
+\NC linepenalty              \NC number          \NC \NC \NR
+\NC lastlinefit              \NC number          \NC \NC \NR
+\NC doublehyphendemerits     \NC number          \NC \NC \NR
+\NC finalhyphendemerits      \NC number          \NC \NC \NR
+\NC hangafter                \NC number          \NC \NC \NR
+\NC interlinepenalty         \NC number or table \NC if a table, then it is an array like \type {\interlinepenalties} \NC \NR
+\NC clubpenalty              \NC number or table \NC if a table, then it is an array like \type {\clubpenalties} \NC \NR
+\NC widowpenalty             \NC number or table \NC if a table, then it is an array like \type {\widowpenalties} \NC \NR
+\NC brokenpenalty            \NC number          \NC \NC \NR
+\NC emergencystretch         \NC number          \NC in scaled points \NC \NR
+\NC hangindent               \NC number          \NC in scaled points \NC \NR
+\NC hsize                    \NC number          \NC in scaled points \NC \NR
+\NC leftskip                 \NC glue_spec node  \NC \NC \NR
+\NC rightskip                \NC glue_spec node  \NC \NC \NR
+\NC pdfignoreddimen          \NC number          \NC in scaled points \NC \NR
+\NC parshape                 \NC table           \NC \NC \NR
+\stoptabulate
+
+Note that there is no interface for \type {\displaywidowpenalties}, you have to
+pass the right choice for \type {widowpenalties} yourself.
+
+The meaning of the various keys should be fairly obvious from the table (the
+names match the \TEX\ and \PDFTEX\ primitives) except for the last 5 entries. The
+four \type {pdf...line...} keys are ignored if their value equals \type
+{pdfignoreddimen}.
+
+It is your own job to make sure that \type {listhead} is a proper paragraph list:
+this function does not add any nodes to it. To be exact, if you want to replace
+the core line breaking, you may have to do the following (when you are not
+actually working in the \type {pre_linebreak_filter} or \type {linebreak_filter}
+callbacks, or when the original list starting at listhead was generated in
+horizontal mode):
+
+\startitemize
+\startitem
+    add an \quote {indent box} and perhaps a \type {local_par} node at the start
+    (only if you need them)
+\stopitem
+\startitem
+    replace any found final glue by an infinite penalty (or add such a penalty,
+    if the last node is not a glue)
+\stopitem
+\startitem
+    add a glue node for the \type {\parfillskip} after that penalty node
+\stopitem
+\startitem
+    make sure all the \type {prev} pointers are OK
+\stopitem
+\stopitemize
+
+The result is a node list, it still needs to be vpacked if you want to assign it
+to a \type {\vbox}.
+
+The returned \type {info} table contains four values that are all numbers:
+
+\starttabulate[|l|p|]
+\NC prevdepth \NC depth of the last line in the broken paragraph \NC \NR
+\NC prevgraf  \NC number of lines in the broken paragraph \NC \NR
+\NC looseness \NC the actual looseness value in the broken paragraph \NC \NR
+\NC demerits  \NC the total demerits of the chosen solution  \NC \NR
+\stoptabulate
+
+Note there are a few things you cannot interface using this function: You cannot
+influence font expansion other than via \type {pdfadjustspacing}, because the
+settings for that take place elsewhere. The same is true for hbadness and hfuzz
+etc. All these are in the \type {hpack()} routine, and that fetches its own
+variables via globals.
+
+\subsubsection{\type {tex.shipout}}
+
+\startfunctioncall
+tex.shipout(<number> n)
+\stopfunctioncall
+
+Ships out box number \type {n} to the output file, and clears the box register.
+
+\section[texconfig]{The \type {texconfig} table}
+
+This is a table that is created empty. A startup \LUA\ script could
+fill this table with a number of settings that are read out by
+the executable after loading and executing the startup file.
+
+\starttabulate[|lT|l|l|p|]
+\NC \ssbf key             \NC \bf type \NC \bf default \NC \bf explanation \NC \NR
+\NC kpse_init             \NC boolean  \NC true
+\NC
+    \type {false} totally disables \KPATHSEA\ initialisation, and enables
+    interpretation of the following numeric key--value pairs. (only ever unset
+    this if you implement {\it all\/} file find callbacks!)
+\NC \NR
+\NC
+    shell_escape          \NC string   \NC \type {'f'} \NC
+    Use \type {'y'} or \type {'t'} or \type {'1'} to enable \type {\write18}
+    unconditionally, \type {'p'} to enable the commands that are listed in \type
+    {shell_escape_commands}
+\NC \NR
+\NC
+    shell_escape_commands \NC string \NC \NC Comma-separated list of command
+    names that may be executed by \type {\write18} even if \type {shell_escape}
+    is set to \type {'p'}. Do {\it not\/} use spaces around commas, separate any
+    required command arguments by using a space, and use the ASCII double quote
+    (\type {"}) for any needed argument or path quoting
+\NC \NR
+
+\NC string_vacancies      \NC number   \NC  75000  \NC cf.\ web2c docs \NC \NR
+\NC pool_free             \NC number   \NC   5000  \NC cf.\ web2c docs \NC \NR
+\NC max_strings           \NC number   \NC  15000  \NC cf.\ web2c docs \NC \NR
+\NC strings_free          \NC number   \NC    100  \NC cf.\ web2c docs \NC \NR
+\NC nest_size             \NC number   \NC     50  \NC cf.\ web2c docs \NC \NR
+\NC max_in_open           \NC number   \NC     15  \NC cf.\ web2c docs \NC \NR
+\NC param_size            \NC number   \NC     60  \NC cf.\ web2c docs \NC \NR
+\NC save_size             \NC number   \NC   4000  \NC cf.\ web2c docs \NC \NR
+\NC stack_size            \NC number   \NC    300  \NC cf.\ web2c docs \NC \NR
+\NC dvi_buf_size          \NC number   \NC  16384  \NC cf.\ web2c docs \NC \NR
+\NC error_line            \NC number   \NC     79  \NC cf.\ web2c docs \NC \NR
+\NC half_error_line       \NC number   \NC     50  \NC cf.\ web2c docs \NC \NR
+\NC max_print_line        \NC number   \NC     79  \NC cf.\ web2c docs \NC \NR
+\NC hash_extra            \NC number   \NC      0  \NC cf.\ web2c docs \NC \NR
+\NC pk_dpi                \NC number   \NC     72  \NC cf.\ web2c docs \NC \NR
+\NC trace_file_names      \NC boolean  \NC true
+\NC
+    \type {false} disables \TEX's normal file open|-|close feedback (the
+    assumption is that callbacks will take care of that)
+\NC \NR
+\NC file_line_error       \NC boolean  \NC false
+\NC
+    do \type {file:line} style error messages
+\NC \NR
+\NC halt_on_error         \NC boolean  \NC false
+\NC
+    abort run on the first encountered error
+\NC \NR
+\NC formatname            \NC string   \NC
+\NC
+    if no format name was given on the commandline, this key will be tested first
+    instead of simply quitting
+\NC \NR
+\NC jobname               \NC string   \NC
+\NC
+    if no input file name was given on the commandline, this key will be tested
+    first instead of simply giving up
+\NC \NR
+\stoptabulate
+
+Note: the numeric values that match web2c parameters are only used if \type
+{kpse_init} is explicitly set to \type {false}. In all other cases, the normal
+values from \type {texmf.cnf} are used.
+
+\section{The \type {texio} library}
+
+This library takes care of the low|-|level I/O interface.
+
+\subsection{Printing functions}
+
+\subsubsection{\type {texio.write}}
+
+\startfunctioncall
+texio.write(<string> target, <string> s, ...)
+texio.write(<string> s, ...)
+\stopfunctioncall
+
+Without the \type {target} argument, writes all given strings to the same
+location(s) \TEX\ writes messages to at this moment. If \type {\batchmode} is in
+effect, it writes only to the log, otherwise it writes to the log and the
+terminal. The optional \type {target} can be one of three possibilities: \type
+{term}, \type {log} or \type {term and log}.
+
+Note: If several strings are given, and if the first of these strings is or might
+be one of the targets above, the \type {target} must be specified explicitly to
+prevent \LUA\ from interpreting the first string as the target.
+
+\subsubsection{\type {texio.write_nl}}
+
+\startfunctioncall
+texio.write_nl(<string> target, <string> s, ...)
+texio.write_nl(<string> s, ...)
+\stopfunctioncall
+
+This function behaves like \type {texio.write}, but make sure that the given
+strings will appear at the beginning of a new line. You can pass a single empty
+string if you only want to move to the next line.
+
+\section[luatokens]{The \type {token} library}
+
+The \type {token} table contains interface functions to \TEX's handling of
+tokens. These functions are most useful when combined with the \type
+{token_filter} callback, but they could be used standalone as well.
+
+A token is represented in \LUA\ as a small table. For the moment, this table
+consists of three numeric entries:
+
+\starttabulate[|l|l|p|]
+\NC \bf index \NC \bf meaning         \NC \bf description \NC \NR
+\NC 1         \NC command code        \NC this is a value between~$0$ and~$130$ (approximately)\NC \NR
+\NC 2         \NC command modifier    \NC this is a value between~$0$ and~$2^{21}$ \NC \NR
+\NC 3         \NC control sequence id \NC for commands that are not the result of control
+                                          sequences, like letters and characters, it is zero,
+                                          otherwise, it is a number pointing into the \quote
+                                          {equivalence table} \NC \NR
+\stoptabulate
+
+\subsection{\type {token.get_next}}
+
+\startfunctioncall
+token t = token.get_next()
+\stopfunctioncall
+
+This fetches the next input token from the current input source, without
+expansion.
+
+\subsection{\type {token.is_expandable}}
+
+\startfunctioncall
+<boolean> b = token.is_expandable(<token> t)
+\stopfunctioncall
+
+This tests if the token \type {t} could be expanded.
+
+\subsection{\type {token.expand}}
+
+\startfunctioncall
+token.expand(<token> t)
+\stopfunctioncall
+
+If a token is expandable, this will expand one level of it, so that the first
+token of the expansion will now be the next token to be read by \type
+{token.get_next()}.
+
+\subsection{\type {token.is_activechar}}
+
+\startfunctioncall
+<boolean> b = token.is_activechar(<token> t)
+\stopfunctioncall
+
+This is a special test that is sometimes handy. Discovering whether some control
+sequence is the result of an active character turned out to be very hard
+otherwise.
+
+\subsection{\type {token.create}}
+
+\startfunctioncall
+token t = token.create(<string> csname)
+token t = token.create(<number> charcode)
+token t = token.create(<number> charcode, <number> catcode)
+\stopfunctioncall
+
+This is the token factory. If you feed it a string, then it is the name of a
+control sequence (without leading backslash), and it will be looked up in the
+equivalence table.
+
+If you feed it number, then this is assumed to be an input character, and an
+optional second number gives its category code. This means it is possible to
+overrule a character's category code, with a few exceptions: the category codes~0
+(escape), 9~(ignored), 13~(active), 14~(comment), and 15 (invalid) cannot occur
+inside a token. The values~0, 9, 14 and~15 are therefore illegal as input to
+\type {token.create()}, and active characters will be resolved immediately.
+
+Note: unknown string sequences and never defined active characters will result in
+a token representing an \quote {undefined control sequence} with a near|-|random
+name. It is {\em not} possible to define brand new control sequences using
+\type {token.create}!
+
+\subsection{\type {token.command_name}}
+
+\startfunctioncall
+<string> commandname = token.command_name(<token> t)
+\stopfunctioncall
+
+This returns the name associated with the \quote {command} value of the token in
+\LUATEX. There is not always a direct connection between these names and
+primitives. For instance, all \type {\ifxxx} tests are grouped under \type
+{if_test}, and the \quote {command modifier} defines which test is to be run.
+
+\subsection{\type {token.command_id}}
+
+\startfunctioncall
+<number> i = token.command_id(<string> commandname)
+\stopfunctioncall
+
+This returns a number that is the inverse operation of the previous command, to
+be used as the first item in a token table.
+
+\subsection{\type {token.csname_name}}
+
+\startfunctioncall
+<string> csname = token.csname_name(<token> t)
+\stopfunctioncall
+
+This returns the name associated with the \quote {equivalence table} value of the
+token in \LUATEX. It returns the string value of the command used to create the
+current token, or an empty string if there is no associated control sequence.
+
+Keep in mind that there are potentially two control sequences that return the
+same csname string: single character control sequences and active characters have
+the same \quote {name}.
+
+\subsection{\type {token.csname_id}}
+
+\startfunctioncall
+<number> i = token.csname_id(<string> csname)
+\stopfunctioncall
+
+This returns a number that is the inverse operation of the previous command, to
+be used as the third item in a token table.
+
+\subsection{The \type {newtoken} libray}
+
+The current \type {token} library will be replaced by a new one that is more
+flexible and powerful. The transition takes place in steps. In version 0.80 we
+have \type {newtoken} and in version 0.85 the old lib will be replaced
+completely. So if you use this new mechanism in production code you need to be
+aware of incompatible updates between 0.80 and 0.90. Because the related in- and
+output code will also be cleaned up and rewritten you should be aware of
+incompatible logging and error reporting too.
+
+The old library presents tokens as triplets or numbers, the new library presents
+a userdata object. The old library used a callback to intercept tokens in the
+input but the new library provides a basic scanner infrastructure that can be
+used to write macros that accept a wide range of arguments. This interface is on
+purpose kept general and as performance is quite ok one can build additional
+parsers without too much overhead. It's up to macro package writers to see how
+they can benefit from this as the main principle behind \LUATEX\ is to provide a
+minimal set of tools and no solutions.
+
+The current functions in the \type {newtoken} namespace are given in the next
+table:
+
+\starttabulate[|lT|lT|p|]
+\NC \bf function \NC \bf argument       \NC \bf result \NC \NR
+\HL
+\NC is_token     \NC token              \NC checks if the given argument is a token userdatum \NC \NR
+\NC get_next     \NC                    \NC returns the next token in the input \NC \NR
+\NC scan_keyword \NC string             \NC returns true if the given keyword is gobbled \NC \NR
+\NC scan_int     \NC                    \NC returns a number \NC \NR
+\NC scan_dimen   \NC infinity, mu-units \NC returns a number representing a dimension and or two numbers being the filler and order \NC \NR
+\NC scan_glue    \NC mu-units           \NC returns a glue spec node \NC \NR
+\NC scan_toks    \NC definer, expand    \NC returns a table of tokens token list (this can become a linked list in later releases) \NC \NR
+\NC scan_code    \NC bitset             \NC returns a character if its category is in the given bitset (representing catcodes) \NC \NR
+\NC scan_string  \NC                    \NC returns a string given between \type {{}}, as \type {\macro} or as sequence of characters with catcode 11 or 12 \NC \NR
+\NC scan_word    \NC                    \NC returns a sequence of characters with catcode 11 or 12 as string \NC \NR
+\NC create       \NC                    \NC returns a userdata token object of the given control sequence name (or character); this interface can change  \NC \NR
+\stoptabulate
+
+The scanners can be considered stable apart from the one scanning for a token.
+This is because futures releases can return a linked list instead of a table (as
+with nodes). The \type {scan_code} function takes an optional number, the \type
+{keyword} function a normal \LUA\ string. The \type {infinity} boolean signals
+that we also permit \type {fill} as dimension and the \type {mu-units} flags the
+scanner that we expect math units. When scanning tokens we can indicate that we
+are defining a macro, in which case the result will also provide information
+about what arguments are expected and in the result this is separated from the
+meaning by a separator token. The \type {expand} flag determines if the list will
+be expanded.
+
+The string scanner scans for something between curly braces and expands on the
+way, or when it sees a control sequence it will return its meaning. Otherwise it
+will scan characters with catcode \type {letter} or \type {other}. So, given the
+following definition:
+
+\startbuffer
+\def\bar{bar}
+\def\foo{foo-\bar}
+\stopbuffer
+
+\typebuffer \getbuffer
+
+we get:
+
+\starttabulate[|l|Tl|l|]
+\NC \type {\directlua{newtoken.scan_string()}{foo}} \NC \directlua{context("{\\red\\type {"..newtoken.scan_string().."}}")} {foo} \NC full expansion \NR
+\NC \type {\directlua{newtoken.scan_string()}foo}   \NC \directlua{context("{\\red\\type {"..newtoken.scan_string().."}}")} foo   \NC letters and others \NR
+\NC \type {\directlua{newtoken.scan_string()}\foo}  \NC \directlua{context("{\\red\\type {"..newtoken.scan_string().."}}")}\foo   \NC meaning \NR
+\stoptabulate
+
+The \type {\foo} case only gives the meaning, but one can pass an already
+expanded definition (\type {\edef}'d). In the case of the braced variant one can of
+course use the \type {\detokenize} and \type {\unexpanded} primitives as there we
+do expand.
+
+The \type {scan_word} scanner can be used to implement for instance a number scanner:
+
+\starttyping
+function newtokens.scan_number(base)
+    return tonumber(newtoken.scan_word(),base)
+end
+\stoptyping
+
+This scanner accepts any valid \LUA\ number so it is a way to pick up floats
+in the input.
+
+The creator function can be used as follows:
+
+\starttyping
+local t = newtoken("relax")
+\stoptyping
+
+This gives back a token object that has the properties of the \type {\relax}
+primitive. The possible properties of tokens are:
+
+\starttabulate[|lT|p|]
+\NC command    \NC a number representing the internal command number \NC \NR
+\NC cmdname    \NC the type of the command (for instance the catcode in case of a
+                   character or the classifier that determines the internal
+                   treatment \NC \NR
+\NC csname     \NC the associated control sequence (if applicable) \NC \NR
+\NC id         \NC the unique id of the token \NC \NR
+%NC tok        \NC \NC \NR % might change
+\NC active     \NC a boolean indicating the active state of the token \NC \NR
+\NC expandable \NC a boolean indicating if the token (macro) is expandable \NC \NR
+\NC protected  \NC a boolean indicating if the token (macro) is protected \NC \NR
+\stoptabulate
+
+The numbers that represent a catcode are the same as in \TEX\ itself, so using
+this information assumes that you know a bit about \TEX's internals. The other
+numbers and names are used consistently but are not frozen. So, when you use them
+for comparing you can best query a known primitive or character first to see the
+values.
+
+More interesting are the scanners. You can use the \LUA\ interface as follows:
+
+\starttyping
+\directlua {
+    function mymacro(n)
+        ...
+    end
+}
+
+\def\mymacro#1{%
+    \directlua {
+        mymacro(\number\dimexpr#1)
+    }%
+}
+
+\mymacro{12pt}
+\mymacro{\dimen0}
+\stoptyping
+
+You can also do this:
+
+\starttyping
+\directlua {
+    function mymacro()
+        local d = newtoken.scan_dimen()
+        ...
+    end
+}
+
+\def\mymacro{%
+    \directlua {
+        mymacro()
+    }%
+}
+
+\mymacro 12pt
+\mymacro \dimen0
+\stoptyping
+
+It is quite clear from looking at the code what the first method needs as
+argument(s). For the second method you need to look at the \LUA\ code to see what
+gets picked up. Instead of passing from \TEX\ to \LUA\ we let \LUA\ fetch from
+the input stream.
+
+In the first case the input is tokenized and then turned into a string when it's
+passed to \LUA\ where it gets interpreted. In the second case only a function
+call gets interpreted but then the input is picked up by explicitly calling the
+scanner functions. These return proper \LUA\ variables so no further conversion
+has to be done. This is more efficient but in practice (given what \TEX\ has to
+do) this effect should not be overestimated. For numbers and dimensions it saves a
+bit but for passing strings conversion to and from tokens has to be done anyway
+(although we can probably speed up the process in later versions if needed).
+
+When the interface is stable and has replaced the old one completely we will add
+some more information here. By that time the internals have been cleaned up a bit
+more so we know then what will stay and go. A positive side effect of this
+transition is that we can simplify the input part because we no longer need to
+intercept using callbacks.
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-logos.tex b/doc/context/sources/general/manuals/luatex/luatex-logos.tex
new file mode 100644
index 000000000..7406dd602
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-logos.tex
@@ -0,0 +1,19 @@
+\startenvironment luatex-logos
+
+\logo[DFONT]     {dfont}
+\logo[CFF]       {cff}
+\logo[CMAP]      {CMap}
+\logo[PATGEN]    {patgen}
+\logo[MP]        {MetaPost}
+\logo[METAPOST]  {MetaPost}
+\logo[MPLIB]     {MPlib}
+\logo[COCO]      {coco}
+\logo[SUNOS]     {SunOS}
+\logo[BSD]       {bsd}
+\logo[SYSV]      {sysv}
+\logo[DPI]       {dpi}
+\logo[DLL]       {dll}
+\logo[OPENOFFICE]{OpenOffice}
+\logo[OCP]       {OCP}
+
+\stopenvironment
diff --git a/doc/context/sources/general/manuals/luatex/luatex-lua.tex b/doc/context/sources/general/manuals/luatex/luatex-lua.tex
new file mode 100644
index 000000000..3fe2ec9ad
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-lua.tex
@@ -0,0 +1,542 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-lua
+
+\startchapter[reference=lua,title={\LUA\ general}]
+
+\section[init]{Initialization}
+
+\subsection{\LUATEX\ as a \LUA\ interpreter}
+
+There are some situations that make \LUATEX\ behave like a standalone \LUA\
+interpreter:
+
+\startitemize[packed]
+\startitem
+    if a \type {--luaonly} option is given on the commandline, or
+\stopitem
+\startitem
+    if the executable is named \type {texlua} or \type {luatexlua}, or
+\stopitem
+\startitem
+    if the only non|-|option argument (file) on the commandline has the extension
+    \type {lua} or \type {luc}.
+\stopitem
+\stopitemize
+
+In this mode, it will set \LUA's \type {arg[0]} to the found script name, pushing
+preceding options in negative values and the rest of the commandline in the
+positive values, just like the \LUA\ interpreter.
+
+\LUATEX\ will exit immediately after executing the specified \LUA\ script and is,
+in effect, a somewhat bulky standalone \LUA\ interpreter with a bunch of extra
+preloaded libraries.
+
+\subsection{\LUATEX\ as a \LUA\ byte compiler}
+
+There are two situations that make \LUATEX\ behave like the \LUA\ byte compiler:
+
+\startitemize[packed]
+\startitem if a \type {--luaconly} option is given on the commandline, or \stopitem
+\startitem if the executable is named \type {texluac} \stopitem
+\stopitemize
+
+In this mode, \LUATEX\ is exactly like \type {luac} from the standalone \LUA\
+distribution, except that it does not have the \type {-l} switch, and that it
+accepts (but ignores) the \type {--luaconly} switch.
+
+\subsection{Other commandline processing}
+
+When the \LUATEX\ executable starts, it looks for the \type {--lua} commandline
+option. If there is no \type {--lua} option, the commandline is interpreted in a
+similar fashion as in traditional \PDFTEX\ and \ALEPH. Some options are accepted
+but have no consequence. The following command|-|line options are understood:
+
+\starttabulate[|lT|p|]
+\NC --fmt=FORMAT                 \NC load the format file \type {FORMAT} \NC\NR
+\NC --lua=FILE                   \NC load and execute a \LUA\ initialization script\NC\NR
+\NC --safer                      \NC disable easily exploitable \LUA\ commands \NC\NR
+\NC --nosocket                   \NC disable the \LUA\ socket library \NC\NR
+\NC --help                       \NC display help and exit \NC\NR
+\NC --ini                        \NC be iniluatex, for dumping formats \NC\NR
+\NC --interaction=STRING         \NC set interaction mode: \type {batchmode}, \type {nonstopmode}
+                                     \type {scrollmode} or \type {errorstopmode} \NC \NR
+\NC --halt-on-error              \NC stop processing at the first error\NC \NR
+\NC --kpathsea-debug=NUMBER      \NC set path searching debugging flags according to
+                                     the bits of \type {NUMBER} \NC \NR
+\NC --progname=STRING            \NC set the program name to \type {STRING} \NC \NR
+\NC --version                    \NC display version and exit \NC \NR
+\NC --credits                    \NC display credits and exit \NC \NR
+\NC --recorder                   \NC enable filename recorder \NC \NR
+\NC --etex                       \NC ignored \NC \NR
+\NC --output-comment=STRING      \NC use \type {STRING} for \DVI\ file comment instead of
+                                     date (no effect for \PDF) \NC \NR
+\NC --output-directory=DIR       \NC use \type {DIR} as the directory to write files to \NC \NR
+\NC --draftmode                  \NC switch on draft mode i.e.\ generate no output in \PDF\ mode \NC \NR
+\NC --output-format=FORMAT       \NC use \type {FORMAT} for job output; \type {FORMAT} is \type {dvi} or
+                                     \type {pdf} \NC \NR
+\NC --[no-]shell-escape          \NC disable/enable \type {\write18{SHELL COMMAND}} \NC \NR
+\NC --enable-write18             \NC enable \type {\write18{SHELL COMMAND}} \NC \NR
+\NC --disable-write18            \NC disable \type {\write18{SHELL COMMAND}} \NC \NR
+\NC --shell-restricted           \NC restrict \type {\write18} to a list of commands
+                                     given in \type {texmf.cnf} \NC \NR
+\NC --debug-format               \NC enable format debugging \NC \NR
+\NC --[no-]file-line-error       \NC disable/enable \type {file:line:error} style messages  \NC \NR
+\NC --[no-]file-line-error-style \NC aliases of \type {--[no-]file-line-error} \NC \NR
+\NC --jobname=STRING             \NC set the job name to \type {STRING} \NC \NR
+\NC --[no-]parse-first-line      \NC ignored \NC \NR
+\NC --translate-file=            \NC ignored \NC \NR
+\NC --default-translate-file=    \NC ignored \NC \NR
+\NC --8bit                       \NC ignored \NC \NR
+\NC --[no-]mktex=FMT             \NC disable/enable \type {mktexFMT} generation with \type {FMT}
+                                     is \type {tex} or \type {tfm} \NC \NR
+\NC --synctex=NUMBER             \NC enable \type {synctex} \NC \NR
+\stoptabulate
+
+A note on the creation of the various temporary files and the \type {\jobname}.
+The value to use for \type {\jobname} is decided as follows:
+
+\startitemize
+\startitem
+  If \type {--jobname} is given on the command line, its argument will be the
+  value for \type {\jobname}, without any changes. The argument will not be used
+  for actual input so it need not exist. The \type {--jobname} switch only
+  controls the \type {\jobname} setting.
+\stopitem
+\startitem
+    Otherwise, \type {\jobname} will be the name of the first file that is read
+    from the file system, with any path components and the last extension (the
+    part following the last \type {.}) stripped off.
+\stopitem
+\startitem
+    An exception to the previous point: if the command line goes into interactive
+    mode (by starting with a command) and there are no files input via \type
+    {\everyjob} either, then the \type {\jobname} is set to \type {texput} as a
+    last resort.
+\stopitem
+\stopitemize
+
+The file names for output files that are generated automatically are created by
+attaching the proper extension (\type {.log}, \type {.pdf}, etc.) to the found
+\type {\jobname}. These files are created in the directory pointed to by \type
+{--output-directory}, or in the current directory, if that switch is not present.
+
+\blank
+
+Without the \type {--lua} option, command line processing works like it does in
+any other web2c-based typesetting engine, except that \LUATEX\ has a few extra
+switches.
+
+If the \type {--lua} option is present, \LUATEX\ will enter an alternative mode
+of commandline processing in comparison to the standard web2c programs.
+
+In this mode, a small series of actions is taken in order. First, it will parse
+the commandline as usual, but it will only interpret a small subset of the
+options immediately: \type {--safer}, \type {--nosocket}, \type
+{--[no-]shell-escape}, \type {--enable-write18}, \type {--disable-write18}, \type
+{--shell-restricted}, \type {--help}, \type {--version}, and \type {--credits}.
+
+Now it searches for the requested \LUA\ initialization script. If it cannot be
+found using the actual name given on the commandline, a second attempt is made by
+prepending the value of the environment variable \type {LUATEXDIR}, if that
+variable is defined in the environment.
+
+Then it checks the various safety switches. You can use those to disable some
+\LUA\ commands that can easily be abused by a malicious document. At the moment,
+\type {--safer} \type {nil}s the following functions:
+
+\starttabulate[|l|l|]
+\NC \bf library \NC \bf functions \NC \NR
+\NC \type {os}   \NC \type {execute} \type {exec} \type {setenv} \type {rename} \type {remove} \type {tmpdir} \NC \NR
+\NC \type {io}   \NC \type {popen} \type {output} \type {tmpfile} \NC \NR
+\NC \type {lfs}  \NC \type {rmdir} \type {mkdir} \type {chdir} \type {lock} \type {touch} \NC \NR
+\stoptabulate
+
+Furthermore, it disables loading of compiled \LUA\ libraries and it makes \type
+{io.open()} fail on files that are opened for anything besides reading.
+
+\type {--nosocket} makes the socket library unavailable, so that \LUA\ cannot use
+networking.
+
+The switches \type {--[no-]shell-escape}, \type {--[enable|disable]-write18}, and
+\type {--shell-restricted} have the same effects as in \PDFTEX, and additionally
+make \type {io.popen()}, \type {os.execute}, \type {os.exec} and \type {os.spawn}
+adhere to the requested option.
+
+Next the initialization script is loaded and executed. From within the script,
+the entire commandline is available in the \LUA\ table \type {arg}, beginning with
+\type {arg[0]}, containing the name of the executable. As consequence, the warning
+about unrecognized option is suppressed.
+
+Commandline processing happens very early on. So early, in fact, that none of
+\TEX's initializations have taken place yet. For that reason, the tables that
+deal with typesetting, like \type {tex}, \type {token}, \type {node} and
+\type {pdf}, are off|-|limits during the execution of the startup file (they
+are nilled). Special care is taken that \type {texio.write} and \type
+{texio.write_nl} function properly, so that you can at least report your actions
+to the log file when (and if) it eventually becomes opened (note that \TEX\ does
+not even know its \type {\jobname} yet at this point). See \in {chapter} [libraries]
+for more information about the \LUATEX-specific \LUA\ extension tables.
+
+Everything you do in the \LUA\ initialization script will remain visible during
+the rest of the run, with the exception of the aforementioned \type {tex},
+\type {token}, \type {node} and \type {pdf} tables: those will be
+initialized to their documented state after the execution of the script. You
+should not store anything in variables or within tables with these four global
+names, as they will be overwritten completely.
+
+We recommend you use the startup file only for your own \TEX|-|independent
+initializations (if you need any), to parse the commandline, set values in the
+\type {texconfig} table, and register the callbacks you need.
+
+\LUATEX\ allows some of the commandline options to be overridden by reading
+values from the \type {texconfig} table at the end of script execution (see the
+description of the \type {texconfig} table later on in this document for more
+details on which ones exactly).
+
+Unless the \type {texconfig} table tells \LUATEX\ not to initialize \KPATHSEA\
+at all (set \type {texconfig.kpse_init} to \type {false} for that), \LUATEX\
+acts on some more commandline options after the initialization script is
+finished: in order to initialize the built|-|in \KPATHSEA\ library properly,
+\LUATEX\ needs to know the correct program name to use, and for that it needs to
+check \type {--progname}, or \type {--ini} and \type {--fmt}, if \type
+{--progname} is missing.
+
+\section{\LUA\ behaviour}
+
+\LUA s \type {tonumber} function may return values in scientific notation,
+thereby confusing the \TEX\ end of things when it is used as the right|-|hand
+side of an assignment to a \type {\dimen} or \type {\count}.
+
+Loading dynamic \LUA\ libraries will fail if there are two \LUA\ libraries loaded
+at the same time (which will typically happen on \type {win32}, because there is
+one \LUA\ 5.2 inside \LUATEX, and another will likely be linked to the \DLL\ file
+of the module itself). We plan to fix that later by switching \LUATEX\ itself to
+using de \DLL\ version of \LUA\ 5.2 inside \LUATEX\ instead of including a static
+version in the binary.
+
+\LUATEX\ is able to use the kpathsea library to find \type {require()}d modules.
+For this purpose, \type {package.searchers[2]} is replaced by a different loader
+function, that decides at runtime whether to use kpathsea or the built|-|in core
+\LUA\ function. It uses \KPATHSEA\ when that is already initialized at that point
+in time, otherwise it reverts to using the normal \type {package.path} loader.
+
+Initialization of \KPATHSEA\ can happen either implicitly (when \LUATEX\ starts
+up and the startup script has not set \type {texconfig.kpse_init} to false), or
+explicitly by calling the \LUA\ function \type {kpse.set_program_name()}.
+
+\LUATEX\ is able to use dynamically loadable \LUA\ libraries, unless
+\type {--safer} was given as an option on the command line. For this purpose,
+\type {package.searchers[3]} is replaced by a different loader function, that
+decides at runtime whether to use \KPATHSEA\ or the built|-|in core \LUA\
+function. It uses \KPATHSEA\ when that is already initialized at that point in
+time, otherwise it reverts to using the normal \type {package.cpath} loader.
+
+This functionality required an extension to kpathsea:
+
+\startnarrower
+There is a new kpathsea file format: \type {kpse_clua_format} that searches for
+files with extension \type {.dll} and \type {.so}. The \type {texmf.cnf} setting
+for this variable is \type {CLUAINPUTS}, and by default it has this value:
+
+\starttyping
+CLUAINPUTS=.:$SELFAUTOLOC/lib/{$progname,$engine,}/lua//
+\stoptyping % $
+
+This path is imperfect (it requires a \TDS\ subtree below the binaries
+directory), but the architecture has to be in the path somewhere, and the
+currently simplest way to do that is to search below the binaries directory only.
+Of course it no big deal to write an alternative loader and use that in a macro
+package.
+
+One level up (a \type {lib} directory parallel to \type {bin}) would have been
+nicer, but that is not doable because \TEXLIVE\ uses a \type {bin/<arch>}
+structure.
+\stopnarrower
+
+In keeping with the other \TEX|-|like programs in \TEXLIVE, the two \LUA\ functions
+\type {os.execute} and \type {io.popen}, as well as the two new functions \type
+{os.exec} and \type {os.spawn} that are explained below, take the value of \type
+{shell_escape} and|/|or \type {shell_escape_commands} in account. Whenever
+\LUATEX\ is run with the assumed intention to typeset a document (and by that we
+mean that it is called as \type {luatex}, as opposed to \type {texlua}, and that
+the commandline option \type {--luaonly} was not given), it will only run the
+four functions above if the matching \type {texmf.cnf} variable(s) or their \type
+{texconfig} (see \in {section} [texconfig]) counterparts allow execution of the
+requested system command. In \quote {script interpreter} runs of \LUATEX, these
+settings have no effect, and all four functions function as normal.
+
+The \type {f:read("*line")} and \type {f:lines()} functions from the io library
+have been adjusted so that they are line|-|ending neutral: any of \type {LF},
+\type {CR} or \type {CR+LF} are acceptable line endings.
+
+\type {luafilesystem} has been extended: there are two extra boolean functions
+(\type {lfs.isdir(filename)} and \type {lfs.isfile(filename)}) and one extra
+string field in its attributes table (\type {permissions}). There is an
+additional function \type {lfs.shortname()} which takes a file name and returns
+its short name on \type {win32} platforms. On other platforms, it just returns
+the given argument. The file name is not tested for existence. Finally, for
+non|-|\type {win32} platforms only, there is the new function \type
+{lfs.readlink()} hat takes an existing symbolic link as argument and returns its
+content. It returns an error on \type {win32}.
+
+The \type {string} library has an extra function: \type {string.explode(s[,m])}.
+This function returns an array containing the string argument \type {s} split
+into sub-strings based on the value of the string argument \type {m}. The second
+argument is a string that is either empty (this splits the string into
+characters), a single character (this splits on each occurrence of that
+character, possibly introducing empty strings), or a single character followed by
+the plus sign \type {+} (this special version does not create empty sub-strings).
+The default value for \type {m} is \quote {\type { +}} (multiple spaces). Note:
+\type {m} is not hidden by surrounding braces as it would be if this function was
+written in \TEX\ macros.
+
+The \type {string} library also has six extra iterators that return strings
+piecemeal:
+
+\startitemize
+\startitem
+    \type {string.utfvalues(s)}: an integer value in the \UNICODE\ range
+\stopitem
+\startitem
+    \type {string.utfcharacters(s)}: a string with a single \UTF-8 token in it
+\stopitem
+\startitem
+    \type {string.characters(s)} \NC a string containing one byte
+\stopitem
+\startitem
+    \type {string.characterpairs(s)} two strings each containing one byte or an
+    empty second string if the string length was odd
+\stopitem
+\startitem
+    \type {string.bytes(s)} a single byte value
+\stopitem
+\startitem
+    \type {string.bytepairs(s)} two byte values or nil instead of a number as
+    its second return value if the string length was odd
+\stopitem
+\stopitemize
+
+The \type {string.characterpairs()} and \type {string.bytepairs()} iterators
+are useful especially in the conversion of \UTF-16 encoded data into \UTF-8.
+
+There is also a two|-|argument form of \type {string.dump()}. The second argument
+is a boolean which, if true, strips the symbols from the dumped data. This
+matches an extension made in \type {luajit}.
+
+The \type {string} library functions \type {len}, \type {lower}, \type {sub}
+etc.\ are not \UNICODE|-|aware. For strings in the \UTF8 encoding, i.e., strings
+containing characters above code point 127, the corresponding functions from the
+\type {slnunicode} library can be used, e.g., \type {unicode.utf8.len}, \type
+{unicode.utf8.lower} etc. The exceptions are \type {unicode.utf8.find}, that
+always returns byte positions in a string, and \type {unicode.utf8.match} and
+\type {unicode.utf8.gmatch}. While the latter two functions in general {\it
+are} \UNICODE|-|aware, they fall|-|back to non|-|\UNICODE|-|aware behavior when
+using the empty capture \type {()} but other captures work as expected. For the
+interpretation of character classes in \type {unicode.utf8} functions refer to
+the library sources at \hyphenatedurl {http://luaforge.net/projects/sln}. Version
+5.3 of \LUA\ will provide some native \UTF8 support.
+
+\blank
+
+The \type {os} library has a few extra functions and variables:
+
+\startitemize
+
+\startitem
+    \type {os.selfdir} is a variable that holds the directory path of the
+    actual executable. For example: \type {\directlua {tex.sprint(os.selfdir)}}.
+\stopitem
+
+\startitem
+    \type {os.exec(commandline)} is a variation on \type {os.execute}. Here
+    \type {commandline} can be either a single string or a single table.
+
+    If the argument is a table: \LUATEX\ first checks if there is a value at
+    integer index zero. If there is, this is the command to be executed.
+    Otherwise, it will use the value at integer index one. (if neither are
+    present, nothing at all happens).
+
+    The set of consecutive values starting at integer~1 in the table are the
+    arguments that are passed on to the command (the value at index~1 becomes
+    \type {arg[0]}). The command is searched for in the execution path, so there
+    is normally no need to pass on a fully qualified pathname.
+
+    If the argument is a string, then it is automatically converted into a table
+    by splitting on whitespace. In this case, it is impossible for the command
+    and first argument to differ from each other.
+
+    In the string argument format, whitespace can be protected by putting (part
+    of) an argument inside single or double quotes. One layer of quotes is
+    interpreted by \LUATEX, and all occurrences of \type {\"}, \type {\'} or \type
+    {\\} within the quoted text are unescaped. In the table format, there is no
+    string handling taking place.
+
+    This function normally does not return control back to the \LUA\ script: the
+    command will replace the current process. However, it will return the two
+    values \type {nil} and \type {'error'} if there was a problem while
+    attempting to execute the command.
+
+    On \MSWINDOWS, the current process is actually kept in memory until after the
+    execution of the command has finished. This prevents crashes in situations
+    where \TEXLUA\ scripts are run inside integrated \TEX\ environments.
+
+    The original reason for this command is that it cleans out the current
+    process before starting the new one, making it especially useful for use in
+    \TEXLUA.
+\stopitem
+
+\startitem
+    \type {os.spawn(commandline)} is a returning version of \type {os.exec},
+    with otherwise identical calling conventions.
+
+    If the command ran ok, then the return value is the exit status of the
+    command. Otherwise, it will return the two values \type {nil} and \type
+    {'error'}.
+\stopitem
+
+\startitem
+    \type {os.setenv('key','value')} sets a variable in the environment.
+    Passing \type {nil} instead of a value string will remove the variable.
+\stopitem
+
+\startitem
+    \type {os.env} is a hash table containing a dump of the variables and
+    values in the process environment at the start of the run. It is writeable,
+    but the actual environment is {\em not\/} updated automatically.
+\stopitem
+
+\startitem
+    \type {os.gettimeofday()} returns the current \quote {\UNIX\ time}, but as a
+    float. This function is not available on the \SUNOS\ platforms, so do not use
+    this function for portable documents.
+\stopitem
+
+\startitem
+    \type {os.times()}returns the current process times according to \ the
+    \UNIX\ C library function \quote {times}. This function is not available on
+    the \MSWINDOWS\ and \SUNOS\ platforms, so do not use this function for
+    portable documents.
+\stopitem
+
+\startitem
+    \type {os.tmpdir()} creates a directory in the \quote {current directory}
+    with the name \type {luatex.XXXXXX} where the \type {X}-es are replaced by a
+    unique string. The function also returns this string, so you can \type
+    {lfs.chdir()} into it, or \type {nil} if it failed to create the directory.
+    The user is responsible for cleaning up at the end of the run, it does not
+    happen automatically.
+\stopitem
+
+\startitem
+    \type {os.type} is a string that gives a global indication of the class of
+    operating system. The possible values are currently \type {windows}, \type
+    {unix}, and \type {msdos} (you are unlikely to find this value \quote {in the
+    wild}).
+\stopitem
+
+\startitem
+    \type {os.name} is a string that gives a more precise indication of the
+    operating system. These possible values are not yet fixed, and for \type
+    {os.type} values \type {windows} and \type {msdos}, the \type {os.name}
+    values are simply \type {windows} and \type {msdos}
+
+    The list for the type \type {unix} is more precise: \type {linux}, \type
+    {freebsd}, \type {kfreebsd}, \type {cygwin}, \type {openbsd}, \type
+    {solaris}, \type {sunos} (pre-solaris), \type {hpux}, \type {irix}, \type
+    {macosx}, \type {gnu} (hurd), \type {bsd} (unknown, but \BSD|-|like), \type
+    {sysv} (unknown, but \SYSV|-|like), \type {generic} (unknown).
+\stopitem
+
+\startitem
+    \type {os.version} is planned as a future extension.
+\stopitem
+
+\startitem
+    \type {os.uname()} returns a table with specific operating system
+    information acquired at runtime. The keys in the returned table are all
+    string valued, and their names are: \type {sysname}, \type {machine}, \type
+    {release}, \type {version}, and \type {nodename}.
+\stopitem
+
+\stopitemize
+
+In stock \LUA, many things depend on the current locale. In \LUATEX, we can't do
+that, because it makes documents unportable.  While \LUATEX\ is running if
+forces the following locale settings:
+
+\starttyping
+LC_CTYPE=C
+LC_COLLATE=C
+LC_NUMERIC=C
+\stoptyping
+
+\section {\LUA\ modules}
+
+The implied use of the built|-|in Lua modules in this section is deprecated. If
+you want to use one of these libraries, please start your source file with a
+proper \type {require} line. At some point \LUATEX\ will switch to loading these
+modules on demand.
+
+Some modules that are normally external to \LUA\ are statically linked in with
+\LUATEX, because they offer useful functionality:
+
+\startitemize
+
+\startitem
+    \type {slnunicode}, from the \type {Selene} libraries, \hyphenatedurl
+    {http://luaforge.net/projects/sln}. (version 1.1) This library has been
+    slightly extended so that the \type {unicode.utf8.*} functions also accept the
+    first 256 values of plane~18. This is the range \LUATEX\ uses for raw binary
+    output, as explained above.
+\stopitem
+
+\startitem
+    \type {luazip}, from the kepler project,
+    \hyphenatedurl{http://www.keplerproject.org/luazip/}. (version 1.2.1, but
+    patched for compilation with \LUA\ 5.2)
+\stopitem
+
+\startitem
+    \type {luafilesystem}, also from the kepler project, \hyphenatedurl
+    {http://www.keplerproject.org/luafilesystem/}. (version 1.5.0)
+\stopitem
+
+\startitem
+    \type {lpeg}, by Roberto Ierusalimschy, \hyphenatedurl
+    {http://www.inf.puc-rio.br/~roberto/lpeg/lpeg.html}. (version 0.10.2) This
+    library is not \UNICODE|-|aware, but interprets strings on a
+    byte|-|per|-|byte basis. This mainly means that \type {lpeg.S} cannot be
+    used with \UTF\ characters encoded in more than two bytes, and thus \type
+    {lpeg.S} will look for one of those two bytes when matching, not the
+    combination of the two. The same is true for \type {lpeg.R}, although the
+    latter will display an error message if used with multibyte characters.
+    Therefore \type {lpeg.R('aä')} results in the message \type {bad argument
+    #1 to 'R' (range must have two characters)}, since to \type {lpeg}, \type {ä}
+    is two 'characters' (bytes), so \type {aä} totals three. In practice this is
+    no real issue.
+\stopitem
+
+\startitem
+    \type {lzlib}, by Tiago Dionizio, \hyphenatedurl
+    {http://luaforge.net/projects/lzlib/}. (version 0.2)
+\stopitem
+
+\startitem
+    \type {md5}, by Roberto Ierusalimschy \hyphenatedurl
+    {http://www.inf.puc-rio.br/~roberto/md5/md5-5/md5.html}.
+\stopitem
+
+\startitem
+    \type {luasocket}, by Diego Nehab \hyphenatedurl
+    {http://w3.impa.br/~diego/software/luasocket/} (version 2.0.2). The \type
+    {.lua} support modules from \type {luasocket} are also preloaded inside the
+    executable, there are no external file dependencies.
+\stopitem
+
+\stopitemize
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-math.tex b/doc/context/sources/general/manuals/luatex/luatex-math.tex
new file mode 100644
index 000000000..88809d9d9
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-math.tex
@@ -0,0 +1,671 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-math
+
+\startchapter[reference=math,title={Math}]
+
+The handling of mathematics in \LUATEX\ differs quite a bit from how \TEX82 (and
+therefore \PDFTEX) handles math. First, \LUATEX\ adds primitives and extends some
+others so that \UNICODE\ input can be used easily. Second, all of \TEX82's
+internal special values (for example for operator spacing) have been made
+accessible and changeable via control sequences. Third, there are extensions that
+make it easier to use \OPENTYPE\ math fonts. And finally, there are some
+extensions that have been proposed in the past that are now added to the engine.
+
+\section{The current math style}
+
+It is possible to discover the math style that will be used for a formula in an
+expandable fashion (while the math list is still being read). To make this
+possible, \LUATEX\ adds the new primitive: \type {\mathstyle}. This is a \quote
+{convert command} like e.g. \type {\romannumeral}: its value can only be read,
+not set.
+
+\subsection{\type {\mathstyle}}
+
+The returned value is between 0 and 7 (in math mode), or $-1$ (all other modes).
+For easy testing, the eight math style commands have been altered so that the can
+be used as numeric values, so you can write code like this:
+
+\starttyping
+\ifnum\mathstyle=\textstyle
+    \message{normal text style}
+\else \ifnum\mathstyle=\crampedtextstyle
+    \message{cramped text style}
+\fi \fi
+\stoptyping
+
+\subsection{\type {\Ustack}}
+
+There are a few math commands in \TEX\ where the style that will be used is not
+known straight from the start. These commands (\type {\over}, \type {\atop},
+\type {\overwithdelims}, \type {\atopwithdelims}) would therefore normally return
+wrong values for \type {\mathstyle}. To fix this, \LUATEX\ introduces a special
+prefix command: \type {\Ustack}:
+
+\starttyping
+$\Ustack {a \over b}$
+\stoptyping
+
+The \type {\Ustack} command will scan the next brace and start a new math group
+with the correct (numerator) math style.
+
+\section{Unicode math characters}
+
+Character handling is now extended up to the full \UNICODE\ range (the \type {\U}
+prefix), which is compatible with \XETEX.
+
+The math primitives from \TEX\ are kept as they are, except for the ones that
+convert from input to math commands: \type {mathcode}, and \type {delcode}. These
+two now allow for a 21-bit character argument on the left hand side of the equals
+sign.
+
+Some of the new \LUATEX\ primitives read more than one separate value. This is
+shown in the tables below by a plus sign in the second column.
+
+The input for such primitives would look like this:
+
+\starttyping
+\def\overbrace{\Umathaccent 0 1 "23DE }
+\stoptyping
+
+Altered \TEX82 primitives:
+
+\starttabulate[|l|l|l|]
+\NC \bf primitive  \NC \bf value range (in hex) \NC \NR
+\NC \type {\mathcode} \NC 0--10FFFF = 0--8000      \NC \NR
+\NC \type {\delcode}  \NC 0--10FFFF = 0--FFFFFF    \NC \NR
+\stoptabulate
+
+Unaltered:
+
+\starttabulate[|l|l|l|]
+\NC \bf primitive     \NC \bf value range (in hex) \NC \NR
+\NC \type {\mathchardef} \NC 0--8000                  \NC \NR
+\NC \type {\mathchar}    \NC 0--7FFF                  \NC \NR
+\NC \type {\mathaccent}  \NC 0--7FFF                  \NC \NR
+\NC \type {\delimiter}   \NC 0--7FFFFFF               \NC \NR
+\NC \type {\radical}     \NC 0--7FFFFFF               \NC \NR
+\stoptabulate
+
+New primitives that are compatible with \XETEX:
+
+\starttabulate[|l|l|l|l|]
+\NC \bf primitive             \NC \bf value range (in hex)             \NC \NR
+\NC \type {\Umathchardef}        \NC 0+0+0--7+FF+10FFFF$^1$               \NC \NR
+\NC \type {\Umathcharnumdef}$^5$ \NC -80000000--7FFFFFFF$^3$              \NC \NR
+\NC \type {\Umathcode}           \NC 0--10FFFF = 0+0+0--7+FF+10FFFF$^1$   \NC \NR
+\NC \type {\Udelcode}            \NC 0--10FFFF = 0+0--FF+10FFFF$^2$       \NC \NR
+\NC \type {\Umathchar}           \NC 0+0+0--7+FF+10FFFF                   \NC \NR
+\NC \type {\Umathaccent}         \NC 0+0+0--7+FF+10FFFF$^{2,4}$           \NC \NR
+\NC \type {\Udelimiter}          \NC 0+0+0--7+FF+10FFFF$^2$               \NC \NR
+\NC \type {\Uradical}            \NC 0+0--FF+10FFFF$^2$                   \NC \NR
+\NC \type {\Umathcharnum}        \NC -80000000--7FFFFFFF$^3$              \NC \NR
+\NC \type {\Umathcodenum}        \NC 0--10FFFF = -80000000--7FFFFFFF$^3$  \NC \NR
+\NC \type {\Udelcodenum}         \NC 0--10FFFF = -80000000--7FFFFFFF$^3$  \NC \NR
+\stoptabulate
+
+Note 1: \type {\Umathchardef<csname>="8"0"0} and \type
+{\Umathchardef<number>="8"0"0} are also accepted.
+
+Note 2: The new primitives that deal with delimiter-style objects do not set up a
+\quote {large family}. Selecting a suitable size for display purposes is expected
+to be dealt with by the font via the \type {\Umathoperatorsize} parameter (more
+information can be found in a following section).
+
+Note 3: For these three primitives, all information is packed into a single
+signed integer. For the first two (\type {\Umathcharnum} and \type {\Umathcodenum}),
+the lowest 21 bits are the character code, the 3 bits above that represent the
+math class, and the family data is kept in the topmost bits (This means that the
+values for math families 128--255 are actually negative). For \type {\Udelcodenum}
+there is no math class; the math family information is stored in the bits
+directly on top of the character code. Using these three commands is not as
+natural as using the two- and three-value commands, so unless you know exactly
+what you are doing and absolutely require the speedup resulting from the faster
+input scanning, it is better to use the verbose commands instead.
+
+Note 4: The \type {\Umathaccent} command accepts optional keywords to control
+various details regarding math accents. See \in {section} [mathacc] below for
+details.
+
+New primitives that exist in \LUATEX\ only (all of these will be explained
+in following sections):
+
+\starttabulate[|l|l|l|l|]
+\NC \bf primitive         \NC \bf value range (in hex) \NC \NR
+\NC \type {\Uroot}           \NC 0+0--FF+10FFFF$^2$       \NC \NR
+\NC \type {\Uoverdelimiter}  \NC 0+0--FF+10FFFF$^2$       \NC \NR
+\NC \type {\Uunderdelimiter} \NC 0+0--FF+10FFFF$^2$       \NC \NR
+\NC \type {\Udelimiterover}  \NC 0+0--FF+10FFFF$^2$       \NC \NR
+\NC \type {\Udelimiterunder} \NC 0+0--FF+10FFFF$^2$       \NC \NR
+\stoptabulate
+
+\section{Cramped math styles}
+
+\LUATEX\ has four new primitives to set the cramped math styles directly:
+
+\starttyping
+\crampeddisplaystyle
+\crampedtextstyle
+\crampedscriptstyle
+\crampedscriptscriptstyle
+\stoptyping
+
+These additional commands are not all that valuable on their own, but they come
+in handy as arguments to the math parameter settings that will be added shortly.
+
+\section{Math parameter settings}
+
+In \LUATEX, the font dimension parameters that \TEX\ used in math typesetting are
+now accessible via primitive commands. In fact, refactoring of the math engine
+has resulted in many more parameters than were accessible before.
+
+\starttabulate
+\NC \bf primitive name              \NC \bf description \NC \NR
+\NC \type {\Umathquad}               \NC the width of 18mu's \NC \NR
+\NC \type {\Umathaxis}               \NC height of the vertical center axis of
+                                        the math formula above the baseline \NC \NR
+\NC \type {\Umathoperatorsize}       \NC minimum size of large operators in display mode \NC \NR
+\NC \type {\Umathoverbarkern}        \NC vertical clearance above the rule \NC \NR
+\NC \type {\Umathoverbarrule}        \NC the width of the rule \NC \NR
+\NC \type {\Umathoverbarvgap}        \NC vertical clearance below the rule \NC \NR
+\NC \type {\Umathunderbarkern}       \NC vertical clearance below the rule \NC \NR
+\NC \type {\Umathunderbarrule}       \NC the width of the rule \NC \NR
+\NC \type {\Umathunderbarvgap}       \NC vertical clearance above the rule \NC \NR
+\NC \type {\Umathradicalkern}        \NC vertical clearance above the rule \NC \NR
+\NC \type {\Umathradicalrule}        \NC the width of the rule \NC \NR
+\NC \type {\Umathradicalvgap}        \NC vertical clearance below the rule \NC \NR
+\NC \type {\Umathradicaldegreebefore}\NC the forward kern that takes place before placement of
+                                        the radical degree \NC \NR
+\NC \type {\Umathradicaldegreeafter} \NC the backward kern that takes place after placement of
+                                        the radical degree \NC \NR
+\NC \type {\Umathradicaldegreeraise} \NC this is the percentage of the total height and depth of
+                                        the radical sign that the degree is raised by. It is
+                                        expressed in \type {percents}, so 60\% is expressed as the
+                                        integer $60$. \NC \NR
+\NC \type {\Umathstackvgap}          \NC vertical clearance between the two
+                                        elements in a \type {\atop} stack \NC \NR
+\NC \type {\Umathstacknumup}         \NC numerator shift upward in \type {\atop} stack \NC \NR
+\NC \type {\Umathstackdenomdown}     \NC denominator shift downward in \type {\atop} stack \NC \NR
+\NC \type {\Umathfractionrule}       \NC the width of the rule in a \type {\over} \NC \NR
+\NC \type {\Umathfractionnumvgap}    \NC vertical clearance between the numerator and the rule \NC \NR
+\NC \type {\Umathfractionnumup}      \NC numerator shift upward in \type {\over} \NC \NR
+\NC \type {\Umathfractiondenomvgap}  \NC vertical clearance between the denominator and the rule \NC \NR
+\NC \type {\Umathfractiondenomdown}  \NC denominator shift downward in \type {\over} \NC \NR
+\NC \type {\Umathfractiondelsize}    \NC minimum delimiter size for \type {\...withdelims} \NC \NR
+\NC \type {\Umathlimitabovevgap}     \NC vertical clearance for limits above operators \NC \NR
+\NC \type {\Umathlimitabovebgap}     \NC vertical baseline clearance for limits above operators \NC \NR
+\NC \type {\Umathlimitabovekern}     \NC space reserved at the top of the limit \NC \NR
+\NC \type {\Umathlimitbelowvgap}     \NC vertical clearance for limits below operators \NC \NR
+\NC \type {\Umathlimitbelowbgap}     \NC vertical baseline clearance for limits below operators \NC \NR
+\NC \type {\Umathlimitbelowkern}     \NC space reserved at the bottom of the limit \NC \NR
+\NC \type {\Umathoverdelimitervgap}  \NC vertical clearance for limits above delimiters \NC \NR
+\NC \type {\Umathoverdelimiterbgap}  \NC vertical baseline clearance for limits above delimiters \NC \NR
+\NC \type {\Umathunderdelimitervgap} \NC vertical clearance for limits below delimiters \NC \NR
+\NC \type {\Umathunderdelimiterbgap} \NC vertical baseline clearance for limits below delimiters \NC \NR
+\NC \type {\Umathsubshiftdrop}       \NC subscript drop for boxes and subformulas \NC \NR
+\NC \type {\Umathsubshiftdown}       \NC subscript drop for characters \NC \NR
+\NC \type {\Umathsupshiftdrop}       \NC superscript drop (raise, actually) for boxes and subformulas \NC \NR
+\NC \type {\Umathsupshiftup}         \NC superscript raise for characters \NC \NR
+\NC \type {\Umathsubsupshiftdown}    \NC subscript drop in the presence of a superscript \NC \NR
+\NC \type {\Umathsubtopmax}          \NC the top of standalone subscripts cannot be higher than this
+                                        above the baseline \NC \NR
+\NC \type {\Umathsupbottommin}       \NC the bottom of standalone superscripts cannot be less than
+                                        this above the baseline \NC \NR
+\NC \type {\Umathsupsubbottommax}    \NC the bottom of the superscript of a combined super- and subscript
+                                        be at least as high as this above the baseline \NC \NR
+\NC \type {\Umathsubsupvgap}         \NC vertical clearance between super- and subscript \NC \NR
+\NC \type {\Umathspaceafterscript}   \NC additional space added after a super- or subscript \NC \NR
+\NC \type {\Umathconnectoroverlapmin}\NC minimum overlap between parts in an extensible recipe \NC \NR
+\stoptabulate
+
+Each of the parameters in this section can be set by a command like this:
+
+\starttyping
+\Umathquad\displaystyle=1em
+\stoptyping
+
+they obey grouping, and you can use \type {\the\Umathquad\displaystyle} if
+needed.
+
+\section{Font-based Math Parameters}
+
+While it is nice to have these math parameters available for tweaking, it would
+be tedious to have to set each of them by hand. For this reason, \LUATEX\
+initializes a bunch of these parameters whenever you assign a font identifier to
+a math family based on either the traditional math font dimensions in the font
+(for assignments to math family~2 and~3 using \TFM|-|based fonts like \type
+{cmsy} and \type {cmex}), or based on the named values in a potential \type
+{MathConstants} table when the font is loaded via Lua. If there is a \type
+{MathConstants} table, this takes precedence over font dimensions, and in that
+case no attention is paid to which family is being assigned to: the \type
+{MathConstants} tables in the last assigned family sets all parameters.
+
+In the table below, the one|-|letter style abbreviations and symbolic tfm font
+dimension names match those using in the \TeX book. Assignments to \type
+{\textfont} set the values for the cramped and uncramped display and text styles.
+Use \type {\scriptfont} for the script styles, and \type {\scriptscriptfont} for the
+scriptscript styles (totalling eight parameters for three font sizes). In the
+\TFM\ case, assignments only happen in family~2 and family~3 (and of course only
+for the parameters for which there are font dimensions).
+
+Besides the parameters below, \LUATEX\ also looks at the \quote {space} font
+dimension parameter. For math fonts, this should be set to zero.
+
+\start
+
+\switchtobodyfont[8pt]
+
+\starttabulate[|l|l|l|p|]
+\NC \bf variable                   \NC \bf style             \NC \bf default value opentype               \NC \bf default value tfm \NC \NR
+\NC \type {\Umathaxis}                \NC --                    \NC AxisHeight                               \NC axis_height \NC \NR
+\NC \type {\Umathoperatorsize}        \NC D, D'                 \NC DisplayOperatorMinHeight                 \NC $^6$ \NC \NR
+\NC \type {\Umathfractiondelsize}     \NC D, D'                 \NC FractionDelimiterDisplayStyleSize$^9$    \NC delim1 \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC FractionDelimiterSize$^9$                \NC delim2 \NC \NR
+\NC \type {\Umathfractiondenomdown}   \NC D, D'                 \NC FractionDenominatorDisplayStyleShiftDown \NC denom1 \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC FractionDenominatorShiftDown             \NC denom2 \NC \NR
+\NC \type {\Umathfractiondenomvgap}   \NC D, D'                 \NC FractionDenominatorDisplayStyleGapMin    \NC 3*default_rule_thickness \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC FractionDenominatorGapMin                \NC default_rule_thickness \NC \NR
+\NC \type {\Umathfractionnumup}       \NC D, D'                 \NC FractionNumeratorDisplayStyleShiftUp     \NC num1 \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC FractionNumeratorShiftUp                 \NC num2 \NC \NR
+\NC \type {\Umathfractionnumvgap}     \NC D, D'                 \NC FractionNumeratorDisplayStyleGapMin      \NC 3*default_rule_thickness \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC FractionNumeratorGapMin                  \NC default_rule_thickness \NC \NR
+\NC \type {\Umathfractionrule}        \NC --                    \NC FractionRuleThickness                    \NC default_rule_thickness \NC \NR
+\NC \type {\Umathlimitabovebgap}      \NC --                    \NC UpperLimitBaselineRiseMin                \NC big_op_spacing3 \NC \NR
+\NC \type {\Umathlimitabovekern}      \NC --                    \NC 0$^1$                                    \NC big_op_spacing5 \NC \NR
+\NC \type {\Umathlimitabovevgap}      \NC --                    \NC UpperLimitGapMin                         \NC big_op_spacing1 \NC \NR
+\NC \type {\Umathlimitbelowbgap}      \NC --                    \NC LowerLimitBaselineDropMin                \NC big_op_spacing4 \NC \NR
+\NC \type {\Umathlimitbelowkern}      \NC --                    \NC 0$^1$                                    \NC big_op_spacing5 \NC \NR
+\NC \type {\Umathlimitbelowvgap}      \NC --                    \NC LowerLimitGapMin                         \NC big_op_spacing2 \NC \NR
+\NC \type {\Umathoverdelimitervgap}   \NC --                    \NC StretchStackGapBelowMin                  \NC big_op_spacing1 \NC \NR
+\NC \type {\Umathoverdelimiterbgap}   \NC --                    \NC StretchStackTopShiftUp                   \NC big_op_spacing3 \NC \NR
+\NC \type {\Umathunderdelimitervgap}  \NC--                     \NC StretchStackGapAboveMin                  \NC big_op_spacing2 \NC \NR
+\NC \type {\Umathunderdelimiterbgap}  \NC--                     \NC StretchStackBottomShiftDown              \NC big_op_spacing4 \NC \NR
+\NC \type {\Umathoverbarkern}         \NC --                    \NC OverbarExtraAscender                     \NC default_rule_thickness \NC \NR
+\NC \type {\Umathoverbarrule}         \NC --                    \NC OverbarRuleThickness                     \NC default_rule_thickness \NC \NR
+\NC \type {\Umathoverbarvgap}         \NC --                    \NC OverbarVerticalGap                       \NC 3*default_rule_thickness \NC \NR
+\NC \type {\Umathquad}                \NC --                    \NC <font_size(f)>$^1$                       \NC math_quad \NC \NR
+\NC \type {\Umathradicalkern}         \NC --                    \NC RadicalExtraAscender                     \NC default_rule_thickness \NC \NR
+\NC \type {\Umathradicalrule}         \NC --                    \NC RadicalRuleThickness                     \NC <not set>$^2$ \NC \NR
+\NC \type {\Umathradicalvgap}         \NC D, D'                 \NC RadicalDisplayStyleVerticalGap           \NC (default_rule_thickness+\crlf
+                                                                                                              (abs(math_x_height)/4))$^3$ \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC RadicalVerticalGap                       \NC (default_rule_thickness+\crlf
+                                                                                                              (abs(default_rule_thickness)/4))$^3$ \NC \NR
+\NC \type {\Umathradicaldegreebefore} \NC --                    \NC RadicalKernBeforeDegree                  \NC <not set>$^2$ \NC \NR
+\NC \type {\Umathradicaldegreeafter}  \NC --                    \NC RadicalKernAfterDegree                   \NC <not set>$^2$ \NC \NR
+\NC \type {\Umathradicaldegreeraise}  \NC --                    \NC RadicalDegreeBottomRaisePercent          \NC <not set>$^{2,7}$ \NC \NR
+\NC \type {\Umathspaceafterscript}    \NC --                    \NC SpaceAfterScript                         \NC script_space$^4$ \NC \NR
+\NC \type {\Umathstackdenomdown}      \NC D, D'                 \NC StackBottomDisplayStyleShiftDown         \NC denom1 \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC StackBottomShiftDown                     \NC denom2 \NC \NR
+\NC \type {\Umathstacknumup}          \NC D, D'                 \NC StackTopDisplayStyleShiftUp              \NC num1 \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC StackTopShiftUp                          \NC num3 \NC \NR
+\NC \type {\Umathstackvgap}           \NC D, D'                 \NC StackDisplayStyleGapMin                  \NC 7*default_rule_thickness \NC \NR
+\NC "                              \NC T, T', S, S', SS, SS' \NC StackGapMin                              \NC 3*default_rule_thickness \NC \NR
+\NC \type {\Umathsubshiftdown}        \NC --                    \NC SubscriptShiftDown                       \NC sub1 \NC \NR
+\NC \type {\Umathsubshiftdrop}        \NC --                    \NC SubscriptBaselineDropMin                 \NC sub_drop \NC \NR
+\NC \type {\Umathsubsupshiftdown}     \NC --                    \NC SubscriptShiftDownWithSuperscript$^8$    \NC \NC \NR
+\NC                                \NC                       \NC \quad\ or SubscriptShiftDown             \NC sub2 \NC \NR
+\NC \type {\Umathsubtopmax}           \NC --                    \NC SubscriptTopMax                          \NC (abs(math_x_height * 4) / 5) \NC \NR
+\NC \type {\Umathsubsupvgap}          \NC --                    \NC SubSuperscriptGapMin                     \NC 4*default_rule_thickness \NC \NR
+\NC \type {\Umathsupbottommin}        \NC --                    \NC SuperscriptBottomMin                     \NC (abs(math_x_height) / 4) \NC \NR
+\NC \type {\Umathsupshiftdrop}        \NC --                    \NC SuperscriptBaselineDropMax               \NC sup_drop \NC \NR
+\NC \type {\Umathsupshiftup}          \NC D                     \NC SuperscriptShiftUp                       \NC sup1 \NC \NR
+\NC "                              \NC T, S, SS,             \NC SuperscriptShiftUp                       \NC sup2 \NC \NR
+\NC "                              \NC D', T', S', SS'       \NC SuperscriptShiftUpCramped                \NC sup3 \NC \NR
+\NC \type {\Umathsupsubbottommax}     \NC --                    \NC SuperscriptBottomMaxWithSubscript        \NC (abs(math_x_height * 4) / 5) \NC \NR
+\NC \type {\Umathunderbarkern}        \NC --                    \NC UnderbarExtraDescender                   \NC default_rule_thickness \NC \NR
+\NC \type {\Umathunderbarrule}        \NC --                    \NC UnderbarRuleThickness                    \NC default_rule_thickness \NC \NR
+\NC \type {\Umathunderbarvgap}        \NC --                    \NC UnderbarVerticalGap                      \NC 3*default_rule_thickness \NC \NR
+\NC \type {\Umathconnectoroverlapmin} \NC --                    \NC MinConnectorOverlap                      \NC 0$^5$ \NC \NR
+\stoptabulate
+
+\stop
+
+Note 1: \OPENTYPE\ fonts set \type {\Umathlimitabovekern} and \type
+{\Umathlimitbelowkern} to zero and set \type {\Umathquad} to the font size of the
+used font, because these are not supported in the \type {MATH} table,
+
+Note 2: \TFM\ fonts do not set \type {\Umathradicalrule} because \TEX82\ uses the
+height of the radical instead. When this parameter is indeed not set when
+\LUATEX\ has to typeset a radical, a backward compatibility mode will kick in
+that assumes that an oldstyle \TEX\ font is used. Also, they do not set \type
+{\Umathradicaldegreebefore}, \type {\Umathradicaldegreeafter}, and \type
+{\Umathradicaldegreeraise}. These are then automatically initialized to
+$5/18$quad, $-10/18$quad, and 60.
+
+Note 3: If tfm fonts are used, then the \type {\Umathradicalvgap} is not set until
+the first time \LUATEX\ has to typeset a formula because this needs parameters
+from both family2 and family3. This provides a partial backward compatibility
+with \TEX82, but that compatibility is only partial: once the \type
+{\Umathradicalvgap} is set, it will not be recalculated any more.
+
+Note 4: (also if tfm fonts are used) A similar situation arises wrt. \type
+{\Umathspaceafterscript}: it is not set until the first time \LUATEX\ has to
+typeset a formula. This provides some backward compatibility with \TEX82. But
+once the \type {\Umathspaceafterscript} is set, \type {\scriptspace} will never be
+looked at again.
+
+Note 5: Tfm fonts set \type {\Umathconnectoroverlapmin} to zero because \TEX82\
+always stacks extensibles without any overlap.
+
+Note 6: The \type {\Umathoperatorsize} is only used in \type {\displaystyle}, and is
+only set in \OPENTYPE\ fonts. In \TFM\ font mode, it is artificially set to one
+scaled point more than the initial attempt's size, so that always the \quote
+{first next} will be tried, just like in \TEX82.
+
+Note 7: The \type {\Umathradicaldegreeraise} is a special case because it is the
+only parameter that is expressed in a percentage instead of as a number of scaled
+points.
+
+Note 8: \type {SubscriptShiftDownWithSuperscript} does not actually exist in the
+\quote {standard} Opentype Math font Cambria, but it is useful enough to be
+added.
+
+Note 9: \type {FractionDelimiterDisplayStyleSize} and \type
+{FractionDelimiterSize} do not actually exist in the \quote {standard} Opentype
+Math font Cambria, but were useful enough to be added.
+
+\section{Math spacing setting}
+
+Besides the parameters mentioned in the previous sections, there are also 64 new
+primitives to control the math spacing table (as explained in Chapter~18 of the
+\TEX book). The primitive names are a simple matter of combining two math atom
+types, but for completeness' sake, here is the whole list:
+
+\starttwocolumns
+\starttyping
+\Umathordordspacing
+\Umathordopspacing
+\Umathordbinspacing
+\Umathordrelspacing
+\Umathordopenspacing
+\Umathordclosespacing
+\Umathordpunctspacing
+\Umathordinnerspacing
+\Umathopordspacing
+\Umathopopspacing
+\Umathopbinspacing
+\Umathoprelspacing
+\Umathopopenspacing
+\Umathopclosespacing
+\Umathoppunctspacing
+\Umathopinnerspacing
+\Umathbinordspacing
+\Umathbinopspacing
+\Umathbinbinspacing
+\Umathbinrelspacing
+\Umathbinopenspacing
+\Umathbinclosespacing
+\Umathbinpunctspacing
+\Umathbininnerspacing
+\Umathrelordspacing
+\Umathrelopspacing
+\Umathrelbinspacing
+\Umathrelrelspacing
+\Umathrelopenspacing
+\Umathrelclosespacing
+\Umathrelpunctspacing
+\Umathrelinnerspacing
+\Umathopenordspacing
+\Umathopenopspacing
+\Umathopenbinspacing
+\Umathopenrelspacing
+\Umathopenopenspacing
+\Umathopenclosespacing
+\Umathopenpunctspacing
+\Umathopeninnerspacing
+\Umathcloseordspacing
+\Umathcloseopspacing
+\Umathclosebinspacing
+\Umathcloserelspacing
+\Umathcloseopenspacing
+\Umathcloseclosespacing
+\Umathclosepunctspacing
+\Umathcloseinnerspacing
+\Umathpunctordspacing
+\Umathpunctopspacing
+\Umathpunctbinspacing
+\Umathpunctrelspacing
+\Umathpunctopenspacing
+\Umathpunctclosespacing
+\Umathpunctpunctspacing
+\Umathpunctinnerspacing
+\Umathinnerordspacing
+\Umathinneropspacing
+\Umathinnerbinspacing
+\Umathinnerrelspacing
+\Umathinneropenspacing
+\Umathinnerclosespacing
+\Umathinnerpunctspacing
+\Umathinnerinnerspacing
+\stoptyping
+\stoptwocolumns
+
+These parameters are of type \type {\muskip}, so setting a parameter can be done
+like this:
+
+\starttyping
+\Umathopordspacing\displaystyle=4mu plus 2mu
+\stoptyping
+
+They are all initialized by initex to the values mentioned in the table in
+Chapter~18 of the \TEX book.
+
+Note 1: for ease of use as well as for backward compatibility, \type
+{\thinmuskip}, \type {\medmuskip} and \type {\thickmuskip} are treated
+especially. In their case a pointer to the corresponding internal parameter is
+saved, not the actual \type {\muskip} value. This means that any later changes to
+one of these three parameters will be taken into account.
+
+Note 2: Careful readers will realise that there are also primitives for the items
+marked \type {*} in the \TEX book. These will not actually be used as those
+combinations of atoms cannot actually happen, but it seemed better not to break
+orthogonality. They are initialized to zero.
+
+\section[mathacc]{Math accent handling}
+
+\LUATEX\ supports both top accents and bottom accents in math mode, and math
+accents stretch automatically (if this is supported by the font the accent comes
+from, of course). Bottom and combined accents as well as fixed-width math accents
+are controlled by optional keywords following \type {\Umathaccent}.
+
+The keyword \type {bottom} after \type {\Umathaccent} signals that a bottom accent
+is needed, and the keyword \type {both} signals that both a top and a bottom
+accent are needed (in this case two accents need to be specified, of course).
+
+Then the set of three integers defining the accent is read. This set of integers
+can be prefixed by the \type {fixed} keyword to indicate that a non-stretching
+variant is requested (in case of both accents, this step is repeated).
+
+A simple example:
+
+\starttyping
+\Umathaccent both fixed 0 0 "20D7 fixed 0 0 "20D7 {example}
+\stoptyping
+
+If a math top accent has to be placed and the accentee is a character and has a
+non-zero \type {top_accent} value, then this value will be used to place the
+accent instead of the \type {\skewchar} kern used by \TEX82.
+
+The \type {top_accent} value represents a vertical line somewhere in the
+accentee. The accent will be shifted horizontally such that its own \type
+{top_accent} line coincides with the one from the accentee. If the \type
+{top_accent} value of the accent is zero, then half the width of the accent
+followed by its italic correction is used instead.
+
+The vertical placement of a top accent depends on the \type {x_height} of the
+font of the accentee (as explained in the \TEX book), but if value that turns out
+to be zero and the font had a MathConstants table, then \type {AccentBaseHeight}
+is used instead.
+
+If a math bottom accent has to be placed, the \type {bot_accent} value is checked
+instead of \type {top_accent}. Because bottom accents do not exist in \TEX82, the
+\type {\skewchar} kern is ignored.
+
+The vertical placement of a bottom accent is straight below the accentee, no
+correction takes place.
+
+\section{Math root extension}
+
+The new primitive \type {\Uroot} allows the construction of a radical noad
+including a degree field. Its syntax is an extension of \type {\Uradical}:
+
+\starttyping
+\Uradical <fam integer> <char integer> <radicand>
+\Uroot    <fam integer> <char integer> <degree> <radicand>
+\stoptyping
+
+The placement of the degree is controlled by the math parameters \type
+{\Umathradicaldegreebefore}, \type {\Umathradicaldegreeafter}, and \type
+{\Umathradicaldegreeraise}. The degree will be typeset in \type
+{\scriptscriptstyle}.
+
+\section{Math kerning in super- and subscripts}
+
+The character fields in a lua-loaded OpenType math font can have a \quote
+{mathkern} table. The format of this table is the same as the \quote {mathkern}
+table that is returned by the \type {fontloader} library, except that all height
+and kern values have to be specified in actual scaled points.
+
+When a super- or subscript has to be placed next to a math item, \LUATEX\ checks
+whether the super- or subscript and the nucleus are both simple character items.
+If they are, and if the fonts of both character imtes are OpenType fonts (as
+opposed to legacy \TEX\ fonts), then \LUATEX\ will use the OpenType MATH
+algorithm for deciding on the horizontal placement of the super- or subscript.
+
+This works as follows:
+
+\startitemize
+    \startitem
+        The vertical position of the script is calculated.
+    \stopitem
+    \startitem
+        The default horizontal position is flat next to the base character.
+    \stopitem
+    \startitem
+        For superscripts, the italic correction of the base character is added.
+    \stopitem
+    \startitem
+        For a superscript, two vertical values are calculated: the bottom of the
+        script (after shifting up), and the top of the base. For a subscript, the two
+        values are the top of the (shifted down) script, and the bottom of the base.
+    \stopitem
+    \startitem
+        For each of these two locations:
+        \startitemize
+            \startitem
+                find the mathkern value at this height for the base (for a subscript
+                placement, this is the bottom_right corner, for a superscript
+                placement the top_right corner)
+            \stopitem
+            \startitem
+                find the mathkern value at this height for the script (for a
+                subscript placement, this is the top_left corner, for a superscript
+                placement the bottom_left corner)
+            \stopitem
+            \startitem
+                add the found values together to get a preliminary result.
+            \stopitem
+        \stopitemize
+    \stopitem
+    \startitem
+        The horizontal kern to be applied is the smallest of the two results from
+        previous step.
+    \stopitem
+\stopitemize
+
+The mathkern value at a specific height is the kern value that is specified by the
+next higher height and kern pair, or the highest one in the character (if there is no
+value high enough in the character), or simply zero (if the character has no mathkern
+pairs at all).
+
+\section{Scripts on horizontally extensible items like arrows}
+
+The primitives \type {\Uunderdelimiter} and \type {\Uoverdelimiter} allow the
+placement of a subscript or superscript on an automatically extensible item and
+\type {\Udelimiterunder} and \type {\Udelimiterover} allow the placement of an
+automatically extensible item as a subscript or superscript on a nucleus. The
+input:
+
+% these produce radical noads .. in fact the code base has the numbers wrong for
+% quite a while, so no one seems to use this
+
+\startbuffer
+$\Uoverdelimiter  0 "2194 {\hbox{\strut  overdelimiter}}$
+$\Uunderdelimiter 0 "2194 {\hbox{\strut underdelimiter}}$
+$\Udelimiterover  0 "2194 {\hbox{\strut  delimiterover}}$
+$\Udelimiterunder 0 "2194 {\hbox{\strut delimiterunder}}$
+\stopbuffer
+
+\typebuffer will render this:
+
+\blank \startnarrower \getbuffer \stopnarrower \blank
+
+The vertical placements are controlled by \type {\Umathunderdelimiterbgap}, \type
+{\Umathunderdelimitervgap}, \type {\Umathoverdelimiterbgap}, and \type
+{\Umathoverdelimitervgap} in a similar way as limit placements on large operators.
+The superscript in \type {\Uoverdelimiter} is typeset in a suitable scripted style,
+the subscript in \type {\Uunderdelimiter} is cramped as well.
+
+\section {Extensible delimiters}
+
+\LUATEX\ internally uses a structure that supports \OPENTYPE\ \quote
+{MathVariants} as well as \TFM\ \quote {extensible recipes}.
+
+\section{Other Math changes}
+
+\subsection {Verbose versions of single-character math commands}
+
+\LUATEX\ defines six new primitives that have the same function as
+\type {^}, \type {_}, \type {$}, and \type {$$}. %$
+
+\starttabulate[|l|l|l|l|]
+\NC \bf primitive           \NC \bf explanation \NC \NR
+\NC \type {\Usuperscript}      \NC Duplicates the functionality of \type {^} \NC \NR
+\NC \type {\Usubscript}        \NC Duplicates the functionality of \type {_} \NC \NR
+\NC \type {\Ustartmath}        \NC Duplicates the functionality of \type {$}, % $
+                                   when used in non-math mode. \NC \NR
+\NC \type {\Ustopmath}         \NC Duplicates the functionality of \type {$}, % $
+                                   when used in inline math mode. \NC \NR
+\NC \type {\Ustartdisplaymath} \NC Duplicates the functionality of \type {$$}, % $$
+                                   when used in non-math mode. \NC \NR
+\NC \type {\Ustopdisplaymath}  \NC Duplicates the functionality of \type {$$}, % $$
+                                   when used in display math mode. \NC \NR
+\stoptabulate
+
+The \type {\Ustopmath} and \type {\Ustopdisplaymath} primitives check if the current
+math mode is the correct one (inline vs.\ displayed), but you can freely intermix
+the four mathon|/|mathoff commands with explicit dollar sign(s).
+
+\subsection{Allowed math commands in non-math modes}
+
+The commands \type {\mathchar}, and \type {\Umathchar} and control sequences that
+are the result of \type {\mathchardef} or \type {\Umathchardef} are also
+acceptable in the horizontal and vertical modes. In those cases, the \type
+{\textfont} from the requested math family is used.
+
+\section{Math todo}
+
+The following items are still todo.
+
+\startitemize
+\startitem
+    Pre-scripts.
+\stopitem
+\startitem
+    Multi-story stacks.
+\stopitem
+\startitem
+    Flattened accents for high characters (maybe).
+\stopitem
+\startitem
+    Better control over the spacing around displays and handling of equation numbers.
+\stopitem
+\startitem
+    Support for multi|-|line displays using \MATHML\ style alignment points.
+\stopitem
+\stopitemize
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-modifications.tex b/doc/context/sources/general/manuals/luatex/luatex-modifications.tex
new file mode 100644
index 000000000..630528bec
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-modifications.tex
@@ -0,0 +1,499 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-modifications
+
+\startchapter[reference=modifications,title={Modifications}]
+
+\startsection[title=The merged engines]
+
+\startsubsection[title=The need for change]
+
+The first version of \LUATEX\ only had a few extra primitives and it was largely
+the same as \PDFTEX. Then we merged substantial parts of \ALEPH\ into the code
+and got more primitives. When we got more stable teh decision was made to clean
+up the rather hybrid nature of the program. This means that some primnitives have
+been promoted to core primitives, often with a different name, and that others
+were removed. This made it possible to start cleaning up the code base. We will
+describe most in following paragraphs.
+
+Besides the expected changes caused by new functionality, there are a number of
+not|-|so|-|expected changes. These are sometimes a side|-|effect of a new
+(conflicting) feature, or, more often than not, a change neccessary to clean up
+the internal interfaces. These will also be mentioned.
+
+\stopsubsection
+
+\startsubsection[title=Changes from \TEX\ 3.1415926]
+
+Of course it all starts with traditional \TEX. Even if we started with \PDFTEX,
+most still comes from the original. But we divert a bit.
+
+\startitemize
+
+\startitem
+    The current code base is written in \CCODE, not \PASCAL. We use \CWEB\
+    when possible.
+\stopitem
+
+\startitem
+    See \in {chapter} [languages] for many small changes related to paragraph
+    building, language handling and hyphenation. The most important change is
+    that adding a brace group in the middle of a word (like in \type {of{}fice})
+    does not prevent ligature creation.
+\stopitem
+
+\startitem
+    There is no pool file, all strings are embedded during compilation.
+\stopitem
+
+\startitem
+    The specifier \type {plus 1 fillll} does not generate an error. The extra
+    \quote{l} is simply typeset.
+\stopitem
+
+\startitem
+    The upper limit to \type {\endlinechar} and \type {\newlinechar} is 127.
+\stopitem
+
+\startitem
+    The hz optimization code has been partially redone so that we no longer need
+    to create extra font instances. The front- and backend have been decoupled and
+    more efficient (\PDF) code is generated.
+\stopitem
+
+\stopitemize
+
+\stopsubsection
+
+\startsubsection[title=Changes from \ETEX\ 2.2]
+
+Being the de factor standard extension of course we provide the \ETEX\
+functionality, but with a few small adaptions.
+
+\startitemize
+
+\startitem
+    The \ETEX\ functionality is always present and enabled so the prepended
+    asterisk or \type {-etex} switch for \INITEX\ is not needed.
+\stopitem
+
+\startitem
+    The \TEXXET\ extension is not present, so the primitives \type
+    {\TeXXeTstate}, \type {\beginR}, \type {\beginL}, \type {\endR} and \type
+    {\endL} are missing.
+\stopitem
+
+\startitem
+    Some of the tracing information that is output by \ETEX's \type
+    {\tracingassigns} and \type {\tracingrestores} is not there.
+\stopitem
+
+\startitem
+    Register management in \LUATEX\ uses the \ALEPH\ model, so the maximum value
+    is 65535 and the implementation uses a flat array instead of the mixed
+    flat|\&|sparse model from \ETEX.
+\stopitem
+
+\startitem
+    The \type {\savinghyphcodes} command is a no|-|op. \in {Chapter} [languages]
+    explains why.
+\stopitem
+
+\startitem
+    When kpathsea is used to find files, \LUATEX\ uses the \type {ofm} file
+    format to search for font metrics. In turn, this means that \LUATEX\ looks at
+    the \type {OFMFONTS} configuration variable (like \OMEGA\ and \ALEPH) instead
+    of \type {TFMFONTS} (like \TEX\ and \PDFTEX). Likewise for virtual fonts
+    (\LUATEX\ uses the variable \type {OVFFONTS} instead of \type {VFFONTS}).
+\stopitem
+
+\stopitemize
+
+\stopsubsection
+
+\startsubsection[title=Changes from \PDFTEX\ 1.40]
+
+Because we want to produce \PDF\ the most natural starting point was the popular
+\PDFTEX\ program. We inherit the stable features, dropped most of the
+experimental code and promoted some functionality to core \LUATEX\ functionality
+which in turn triggered renaming primitives.
+
+\startitemize
+
+\startitem
+    The (experimental) support for snap nodes has been removed, because it is
+    much more natural to build this functionality on top of node processing and
+    attributes. The associated primitives that are now gone are: \type
+    {\pdfsnaprefpoint}, \type {\pdfsnapy}, and \type {\pdfsnapycomp}.
+\stopitem
+
+\startitem
+    The (experimental) support for specialized spacing around nodes has also been
+    removed. The associated primitives that are now gone are: \type
+    {\pdfadjustinterwordglue}, \type {\pdfprependkern}, and \type {\pdfappendkern}, as
+    well as the five supporting primitives \type {\knbscode}, \type {\stbscode}, \type
+    {\shbscode}, \type {\knbccode}, and \type {\knaccode}.
+\stopitem
+
+\startitem
+    A number of \quote {pdftex primitives} have been removed as they can be
+    implemented using \LUA:
+
+    \start \raggedright
+    \type {\pdfelapsedtime}, \type {\pdfescapehex}, \type {\pdfescapename}, \type
+    {\pdfescapestring}, \type {\pdffiledump}, \type {\pdffilemoddate}, \type
+    {\pdffilesize}, \type {\pdfforcepagebox}, \type {\pdflastmatch}, \type
+    {\pdfmatch}, \type {\pdfmdfivesum}, \type {\pdfmovechars}, \type
+    {\pdfoptionalwaysusepdfpagebox}, \type {\pdfoptionpdfinclusionerrorlevel},
+    \type {\pdfresettimer}, \type {\pdfshellescape}, \type {\pdfstrcmp} and \type
+    {\pdfunescapehex}
+    \par \stop
+\stopitem
+
+\startitem
+    The version related primitives \type {\pdftexbanner}, \type {\pdftexversion}
+    and \type {\pdftexrevision} are no longer present as there is no longer a
+    strict relationship with \PDFTEX\ development.
+\stopitem
+
+\startitem
+    The experimental snapper mechanism has been removed and therefore also the
+    primitives:
+
+    \start \raggedright
+    \type {\pdfignoreddimen}, \type {\pdffirstlineheight}, \type
+    {\pdfeachlineheight}, \type {\pdfeachlinedepth} and \type
+    {\pdflastlinedepth}
+    \par \stop
+\stopitem
+
+\startitem
+    The experimental primitives \type {\primitive}, \type {\ifprimitive}, \type
+    {\ifabsnum} and \type {\ifabsdim} are promoted to core primitives. The \type
+    {\pdf*} prefixed originals are not available.
+\stopitem
+
+\startitem
+    The \PNG\ transparency fix from 1.40.6 is not applied as high|-|level
+    support is pending.
+\stopitem
+
+\startitem
+    Two extra token lists are provides, \type {\pdfxformresources} and \type
+    {\pdfxformattr}, as an alternative to \type {\pdfxform} keywords.
+\stopitem
+
+\startitem
+    The current version of \LUATEX\ no longer replaces and|/|or merges fonts in
+    embedded pdf files with fonts of the enveloping \PDF\ document. This
+    regression may be temporary, depending on how the rewritten font backend will
+    look like.
+\stopitem
+
+\startitem
+    The primitives \type {\pdfpagewidth} and \type {\pdfpageheight} have been removed
+    because \type {\pagewidth} and \type {\pageheight} have that purpose.
+\stopitem
+
+\startitem
+    The primitives \type {\pdfnormaldeviate}, \type {\pdfuniformdeviate}, \type
+    {\pdfsetrandomseed} and \type {\pdfrandomseed} have been promoted to core
+    primitives without \type {pdf} prefix so the original commands are no longer
+    recognized.
+\stopitem
+
+\startitem
+    The primitives \type {\ifincsname}, \type {\expanded} and \type {\quitvmode} are now
+    core primitives.
+\stopitem
+
+\startitem
+    As the hz and protrusion mechanism are part of the core the related
+    primitives \type {\lpcode}, \type {\rpcode}, \type {\efcode}, \type
+    {\leftmarginkern}, \type {\rightmarginkern} are promoted to core primitives. The
+    two commands \type {\protrudechars} and \type {\adjustspacing} replace their
+    prefixed with \type {\pdf} originals.
+\stopitem
+
+\startitem
+    The \type {\tagcode} primitive is promoted to core primitive.
+\stopitem
+
+\startitem
+    The \type {\letterspacefont} feature is now part of the core but will not be
+    changed (improved). We just provide it for legacy use.
+\stopitem
+
+\startitem
+    The \type {\pdfnoligatures} primitive is now \type {\ignoreligaturesinfont}.
+\stopitem
+
+\startitem
+    The \type {\pdffontexpand} primitive is now \type {\expandglyphsinfont}.
+\stopitem
+
+\startitem
+    Because position tracking is also available in \DVI\ mode the
+    \type {\savepos}, \type {\lastxpos} and \type {\lastypos} commands now
+    replace their \type {pdf} prefixed originals.
+\stopitem
+
+\startitem
+    Candidates for removal are \type {\pdfcolorstackinit} and \type
+    {\pdfcolorstack}.
+\stopitem
+
+\startitem
+    Candidates for replacement are \type {\pdfoutput} (\type {\outputmode}) and
+    \type {\pdfmatrix} (something with a normal syntax).
+\stopitem
+
+\stopitemize
+
+\stopsubsection
+
+\startsubsection[title=Changes from \ALEPH\ RC4]
+
+Because we wanted proper directional typesetting the \ALEPH\ mechanisms looked
+most attractive. These are rather close to the ones provided by \OMEGA, so what
+we say next applies to both these programs.
+
+\startitemize
+
+\startitem
+    The extended 16-bit math primitives (\type {\omathcode} etc.) have been
+    removed.
+\stopitem
+
+\startitem
+    The \OCP\ processing is no longer supported at all. As a consequence, the
+    following primitives have been removed:
+
+    \start \raggedright
+    \type {\ocp}, \type {\externalocp}, \type {\ocplist}, \type {\pushocplist},
+    \type {\popocplist}, \type {\clearocplists}, \type {\addbeforeocplist}, \type
+    {\addafterocplist}, \type {\removebeforeocplist}, \type {\removeafterocplist}
+    and \type {\ocptracelevel}
+    \par \stop
+\stopitem
+
+\startitem
+    \LUATEX\ only understands 4~of the 16~direction specifiers of \ALEPH: \type
+    {TLT} (latin), \type {TRT} (arabic), \type {RTT} (cjk), \type {LTL}
+    (mongolian). All other direction specifiers generate an error.
+\stopitem
+
+\startitem
+    The input translations from \ALEPH\ are not implemented, the related
+    primitives are not available:
+
+    \start \raggedright
+    \type {\DefaultInputMode}, \type {\noDefaultInputMode}, \type {\noInputMode},
+    \type {\InputMode}, \type {\DefaultOutputMode}, \type {\noDefaultOutputMode},
+    \type {\noOutputMode}, \type {\OutputMode}, \type {\DefaultInputTranslation},
+    \type {\noDefaultInputTranslation}, \type {\noInputTranslation}, \type
+    {\InputTranslation}, \type {\DefaultOutputTranslation}, \type
+    {\noDefaultOutputTranslation}, \type {\noOutputTranslation} and \type
+    {\OutputTranslation}
+    \par \stop
+\stopitem
+
+\startitem
+    Several bugs hav ebeen fixed. The \type {\hoffset} bug when \type {\pagedir TRT}
+    is gone, removing the need for an explicit fix to \type {\hoffset}. Also bug
+    causing \type {\fam} to fail for family numbers above 15 is fixed. A fair amount
+    of other minor bugs are fixed as well, most of these related to \type
+    {\tracingcommands} output.
+\stopitem
+
+\startitem
+    The scanner for direction specifications now allows an optional space after
+    the direction is completely parsed.
+\stopitem
+
+\startitem
+    The \type {^^} notation can come in five and six item repetitions also, to
+    insert characters that do not fit in the BMP.
+\stopitem
+
+\startitem
+    Glues {\it immediately after} direction change commands are not legal
+    breakpoints.
+\stopitem
+
+\startitem
+    Several mechanisms that need to be right|-|to|-|left aware have been
+    improved. For instance placement of formula numbers.
+\stopitem
+
+\startitem
+    The page dimension related primitives \type {\pagewidth} and \type {\pageheight} have
+    been promoted to core primitives.
+\stopitem
+
+\startitem
+    The primitives \type {\charwd}, \type {\charht}, \type {\chardp} and \type {\charit}
+    have been removes as we have the \ETEX\ variants \type {\fontchar*}.
+\stopitem
+
+\startitem
+    The two dimension registers \type {\pagerightoffset} and \type
+    {\pagebottomoffset} are now core primitives.
+\stopitem
+
+\startitem
+    The direction related primitives \type {\pagedir}, \type {\bodydir}, \type
+    {\pardir}, \type {\textdir}, \type {\mathdir} and \type {\boxdir} are now
+    core primitives.
+\stopitem
+
+\startitem
+    The promotion of primitives to core primitives as well as the removed of all
+    others mean that the initialization namespace \type {aleph} is gone.
+\stopitem
+
+\stopitemize
+
+\stopsubsection
+
+\startsubsection[title=Changes from standard \WEBC]
+
+The compilation framework is \WEBC\ and we keep using that but without the
+\PASCAL\ to \CCODE\ step. This framework also provides some common features that
+deal with reading bytes from files and locating files in \TDS. This is what we do
+different:
+
+\startitemize
+
+\startitem
+    There is no mltex support.
+\stopitem
+
+\startitem
+    There is no enctex support.
+\stopitem
+
+\startitem
+    The following commandline switches are silently ignored, even in non|-|\LUA\
+    mode: \type {-8bit}, \type {-translate-file}, \type {-mltex}, \type {-enc}
+    and \type {-etex}.
+\stopitem
+
+\startitem
+    The \type {\openout} whatsits are not written to the log file.
+\stopitem
+
+\startitem
+    Some of the so|-|called web2c extensions are hard to set up in non|-|\KPSE\
+    mode because \type {texmf.cnf} is not read: \type {shell-escape} is off (but
+    that is not a problem because of \LUA's \type {os.execute}), and the paranoia
+    checks on \type {openin} and \type {openout} do not happen (however, it is
+    easy for a \LUA\ script to do this itself by overloading \type {io.open}).
+\stopitem
+
+\startitem
+    The \quote{E} option does not do anything useful.
+\stopitem
+
+\stopitemize
+
+\stopsubsection
+
+\stopsection
+
+\startsection[title=Implementation notes]
+
+\startsubsection[title=Memory allocation]
+
+The single internal memory heap that traditional \TEX\ used for tokens and nodes
+is split into two separate arrays. Each of these will grow dynamically when
+needed.
+
+The \type {texmf.cnf} settings related to main memory are no longer used (these
+are: \type {main_memory}, \type {mem_bot}, \type {extra_mem_top} and \type
+{extra_mem_bot}). \quote {Out of main memory} errors can still occur, but the
+limiting factor is now the amount of RAM in your system, not a predefined limit.
+
+Also, the memory (de)allocation routines for nodes are completely rewritten. The
+relevant code now lives in the C file \type {texnode.c}, and basically uses a
+dozen or so \quote {avail} lists instead of a doubly|-|linked model. An extra
+function layer is added so that the code can ask for nodes by type instead of
+directly requisitioning a certain amount of memory words.
+
+Because of the split into two arrays and the resulting differences in the data
+structures, some of the macros have been duplicated. For instance, there are now
+\type {vlink} and \type {vinfo} as well as \type {token_link} and \type
+{token_info}. All access to the variable memory array is now hidden behind a
+macro called \type {vmem}.
+
+The implementation of the growth of two arrays (via reallocation) introduces a
+potential pitfall: the memory arrays should never be used as the left hand side
+of a statement that can modify the array in question.
+
+The input line buffer and pool size are now also reallocated when needed, and the
+\type {texmf.cnf} settings \type {buf_size} and \type {pool_size} are silently
+ignored.
+
+\stopsubsection
+
+\startsubsection[title=Sparse arrays]
+
+The \type {\mathcode}, \type {\delcode}, \type {\catcode}, \type {\sfcode}, \type {\lccode}
+and \type {\uccode} tables are now sparse arrays that are implemented in~\CCODE.
+They are no longer part of the \TEX\ \quote {equivalence table} and because each
+had 1.1 million entries with a few memory words each, this makes a major
+difference in memory usage.
+
+The \type {\catcode}, \type {\sfcode}, \type {\lccode} and \type {\uccode} assignments do
+not yet show up when using the etex tracing routines \type {\tracingassigns} and
+\type {\tracingrestores} (code simply not written yet).
+
+A side|-|effect of the current implementation is that \type {\global} is now more
+expensive in terms of processing than non|-|global assignments.
+
+See \type {mathcodes.c} and \type {textcodes.c} if you are interested in the
+details.
+
+Also, the glyph ids within a font are now managed by means of a sparse array and
+glyph ids can go up to index $2^{21}-1$.
+
+\stopsubsection
+
+\startsubsection[title=Simple single-character csnames]
+
+Single|-|character commands are no longer treated specially in the internals,
+they are stored in the hash just like the multiletter csnames.
+
+The code that displays control sequences explicitly checks if the length is one
+when it has to decide whether or not to add a trailing space.
+
+Active characters are internally implemented as a special type of multi|-|letter
+control sequences that uses a prefix that is otherwise impossible to obtain.
+
+\stopsubsection
+
+\startsubsection[title=Compressed format]
+
+The format is passed through zlib, allowing it to shrink to roughly half of the
+size it would have had in uncompressed form. This takes a bit more \CPU\ cycles
+but much less disk \IO, so it should still be faster.
+
+\stopsubsection
+
+\startsubsection[title=Binary file reading]
+
+All of the internal code is changed in such a way that if one of the \type
+{read_xxx_file} callbacks is not set, then the file is read by a C function using
+basically the same convention as the callback: a single read into a buffer big
+enough to hold the entire file contents. While this uses more memory than the
+previous code (that mostly used \type {getc} calls), it can be quite a bit faster
+(depending on your I/O subsystem).
+
+\stopsubsection
+
+\stopsection
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-nodes.tex b/doc/context/sources/general/manuals/luatex/luatex-nodes.tex
new file mode 100644
index 000000000..6d4127341
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-nodes.tex
@@ -0,0 +1,1291 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-nodes
+
+\startchapter[reference=nodes,title={Nodes}]
+
+\section{\LUA\ node representation}
+
+\TEX's nodes are represented in \LUA\ as userdata object with a variable set of
+fields. In the following syntax tables, such the type of such a userdata object
+is represented as \syntax {<node>}.
+
+The current return value of \type {node.types()} is:
+\startluacode
+    for id, name in table.sortedhash(node.types()) do
+        context.type(name)
+        context(" (%s), ",id)
+    end
+    context.removeunwantedspaces()
+    context.removepunctuation()
+\stopluacode
+. % period
+
+The \type {\lastnodetype} primitive is \ETEX\ compliant. The valid range is still
+$[-1,15]$ and glyph nodes (formerly known as char nodes) have number~0 while
+ligature nodes are mapped to~7. That way macro packages can use the same symbolic
+names as in traditional \ETEX. Keep in mind that the internal node numbers are
+different and that there are more node types than~15.
+
+\subsection{Auxiliary items}
+
+A few node|-|typed userdata objects do not occur in the \quote {normal} list of
+nodes, but can be pointed to from within that list. They are not quite the same
+as regular nodes, but it is easier for the library routines to treat them as if
+they were.
+
+\subsubsection{glue_spec items}
+
+Skips are about the only type of data objects in traditional \TEX\ that are not a
+simple value. The structure that represents the glue components of a skip is
+called a \type {glue_spec}, and it has the following accessible fields:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf key     \NC \bf type \NC \bf explanation \NC \NR
+\NC width         \NC number   \NC \NC \NR
+\NC stretch       \NC number   \NC \NC \NR
+\NC stretch_order \NC number   \NC \NC \NR
+\NC shrink        \NC number   \NC \NC \NR
+\NC shrink_order  \NC number   \NC \NC \NR
+\NC writable      \NC boolean  \NC If this is true, you can't assign to this
+                                   \type {glue_spec} because it is one of the
+                                   preallocated special cases. \NC \NR
+\stoptabulate
+
+These objects are reference counted, so there is actually an extra read-only
+field named \type {ref_count} as well. This item type will likely disappear in
+the future, and the glue fields themselves will become part of the nodes
+referencing glue items.
+
+The effective width of some glue subtypes depends on the stretch or shrink needed
+to make the encapsulating box fit its dimensions. For instance, in a paragraph
+lines normally have glue representing spaces and these stretch of shrink to make
+the content fit in the available space. The \type {effective_glue} function that
+takes a glue node and a parent (hlist or vlist) returns the effective width of
+that glue item.
+
+\subsubsection{attribute_list and attribute items}
+
+The newly introduced attribute registers are non|-|trivial, because the value
+that is attached to a node is essentially a sparse array of key|-|value pairs.
+
+It is generally easiest to deal with attribute lists and attributes by using the
+dedicated functions in the \type {node} library, but for completeness, here is
+the low|-|level interface.
+
+An \type {attribute_list} item is used as a head pointer for a list of attribute
+items. It has only one user-visible field:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type \NC \bf explanation \NC \NR
+\NC next \NC \syntax{<node>} \NC
+    pointer to the first attribute
+\NC \NR
+\stoptabulate
+
+A normal node's attribute field will point to an item of type \type
+{attribute_list}, and the \type {next} field in that item will point to the first
+defined \quote {attribute} item, whose \type {next} will point to the second
+\quote {attribute} item, etc.
+
+Valid fields in \type {attribute} items:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC next        \NC \syntax{<node>} \NC pointer to the next attribute \NC \NR
+\NC number      \NC number          \NC the attribute type id \NC \NR
+\NC value       \NC number          \NC the attribute value \NC \NR
+\stoptabulate
+
+As mentioned it's better to use the official helpers rather than edit these
+fields directly. For instance the \type {prev} field is used for other purposes
+and there is no double linked list.
+
+\subsubsection{action item}
+
+Valid fields: \showfields{action}\crlf
+Id: \showid{action}
+
+These are a special kind of item that only appears inside \PDF\ start link
+objects.
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type         \NC \bf explanation \NC \NR
+\NC action_type \NC number           \NC \NC \NR
+\NC action_id   \NC number or string \NC \NC \NR
+\NC named_id    \NC number           \NC \NC \NR
+\NC file        \NC string           \NC \NC \NR
+\NC new_window  \NC number           \NC \NC \NR
+\NC data        \NC string           \NC \NC \NR
+\NC ref_count   \NC number           \NC
+    read-only
+\NC \NR
+\stoptabulate
+
+\subsection{Main text nodes}
+
+These are the nodes that comprise actual typesetting commands.
+
+A few fields are present in all nodes regardless of their type, these are:
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC next        \NC \syntax{<node>} \NC the next node in a list, or nil \NC \NR
+\NC id          \NC number          \NC the node's type (\type {id}) number \NC \NR
+\NC subtype     \NC number          \NC the node \type {subtype} identifier \NC \NR
+\stoptabulate
+
+The \type {subtype} is sometimes just a stub entry. Not all nodes actually use
+the \type {subtype}, but this way you can be sure that all nodes accept it as a
+valid field name, and that is often handy in node list traversal. In the
+following tables \type {next} and \type {id} are not explicitly mentioned.
+
+Besides these three fields, almost all nodes also have an \type {attr} field, and
+there is a also a field called \type {prev}. That last field is always present,
+but only initialized on explicit request: when the function \type {node.slide()}
+is called, it will set up the \type {prev} fields to be a backwards pointer in
+the argument node list.
+
+\subsubsection{hlist nodes}
+
+Valid fields: \showfields{hlist}\crlf
+Id: \showid{hlist}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC \type {0} = unknown origin,
+                                        \type {1} = created by linebreaking,
+                                        \type {2} = explicit box command,
+                                        \type {3} = paragraph indentation box,
+                                        \type {4} = alignment column or row,
+                                        \type {5} = alignment cell \NC \NR
+\NC attr        \NC \syntax{<node>} \NC The head of the associated attribute
+                                        list \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC shift       \NC number          \NC a displacement perpendicular to the
+                                        character progression direction \NC \NR
+\NC glue_order  \NC number          \NC a number in the range $[0,4]$, indicating
+                                        the glue order \NC \NR
+\NC glue_set    \NC number          \NC the calculated glue ratio \NC \NR
+\NC glue_sign   \NC number          \NC \type {0} = normal,
+                                        \type {1} = stretching,
+                                        \type {2} = shrinking \NC \NR
+\NC head        \NC \syntax{<node>} \NC the first node of the body of this
+                                        list \NC \NR
+\NC dir         \NC string          \NC the direction of this box,
+                                        see~\in[dirnodes] \NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the \type {head} field unless you are sure
+its internal link structure is correct, otherwise an error may result.
+
+Note: the new field name \type {head} was introduced in 0.65 to replace the old
+name \type {list}. Use of the name \type {list} is now deprecated, but it will
+stay available until at least version 0.80.
+
+\subsubsection{vlist nodes}
+
+Valid fields: As for hlist, except that \quote {shift} is a displacement
+perpendicular to the line progression direction, and \quote {subtype} only has
+subtypes~0, 4, and~5.
+
+\subsubsection{rule nodes}
+
+Valid fields: \showfields{rule}\crlf
+Id: \showid{rule}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC unused \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC the width of the rule; the special value
+                                        $-1073741824$ is used for \quote
+                                        {running} glue dimensions \NC \NR
+\NC height      \NC number          \NC the height of the rule (can be
+                                        negative) \NC \NR
+\NC depth       \NC number          \NC the depth of the rule (can be
+                                        negative) \NC \NR
+\NC dir         \NC string          \NC the direction of this rule,
+                                        see~\in[dirnodes] \NC \NR
+\stoptabulate
+
+\subsubsection{ins nodes}
+
+Valid fields: \showfields{ins}\crlf
+Id: \showid{ins}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC the insertion class \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC cost        \NC number          \NC the penalty associated with this
+                                        insert \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC head/list   \NC \syntax{<node>} \NC the first node of the body of this
+                                        insert \NC \NR
+\NC spec        \NC \syntax{<node>} \NC a pointer to the \type {\splittopskip}
+                                        glue spec \NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the \type {head} field unless you are sure
+its internal link structure is correct, otherwise an error may be result. You can use
+\type {list} instead (often in functions you want to use local variable swith similar
+names and both names are equally sensible).
+
+\subsubsection{mark nodes}
+
+Valid fields: \showfields{mark}\crlf
+Id: \showid{mark}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC unused \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC class       \NC number          \NC the mark class \NC \NR
+\NC mark        \NC table           \NC a table representing a token list \NC \NR
+\stoptabulate
+
+\subsubsection{adjust nodes}
+
+Valid fields: \showfields{adjust}\crlf
+Id: \showid{adjust}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC \type {0} = normal,
+                                        \type {1} = \quote{pre} \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC head/list   \NC \syntax{<node>} \NC adjusted material \NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the \type {head} field unless you are sure
+its internal link structure is correct, otherwise an error may be result.
+
+\subsubsection{disc nodes}
+
+Valid fields: \showfields{disc}\crlf
+Id: \showid{disc}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC indicates the source of a discretionary:
+                                       \type {0} = the \type {\discretionary} command,
+                                       \type {1} = the \type {\-} command,
+                                       \type {2} = added automatically following a \type {-},
+                                       \type {3} = added by the hyphenation algorithm (simple),
+                                       \type {4} = added by the hyphenation algorithm (hard, first item),
+                                       \type {5} = added by the hyphenation algorithm (hard, second item) \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC pre         \NC \syntax{<node>} \NC pointer to the pre|-|break text \NC \NR
+\NC post        \NC \syntax{<node>} \NC pointer to the post|-|break text \NC \NR
+\NC replace     \NC \syntax{<node>} \NC pointer to the no|-|break text \NC \NR
+\NC penalty     \NC number          \NC the penalty associated with the break,
+                                        normally \type {\hyphenpenalty} or \type
+                                        {\exhyphenpenalty} \NC \NR
+\stoptabulate
+
+The subtype numbers~4 and~5 belong to the \quote {of-f-ice} explanation given
+elsewhere.
+
+Warning: never assign a node list to the \type {pre}, \type {post} or \type
+{replace} field unless you are sure its internal link structure is correct,
+otherwise an error may be result. This limnitation will disappear in the future,
+
+\subsubsection{math nodes}
+
+Valid fields: \showfields{math}\crlf
+Id: \showid{math}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC \type {0} = on,
+                                        \type {1} = off \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC surround    \NC number          \NC  width of the \type {\mathsurround} kern \NC \NR
+\stoptabulate
+
+\subsubsection{glue nodes}
+
+Valid fields: \showfields{glue}\crlf
+Id: \showid{glue}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC \type {0} = \type {\skip},
+                                        \type {1-18} = internal glue parameters,
+                                        \type {100-103} = \quote {leader} subtypes \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC spec        \NC \syntax{<node>} \NC pointer to a glue_spec item \NC \NR
+\NC leader      \NC \syntax{<node>} \NC pointer to a box or rule for leaders \NC \NR
+\stoptabulate
+
+The exact meanings of the subtypes are as follows:
+
+\starttabulate[|rT|l|]
+\NC   1 \NC \type {\lineskip}              \NC \NR
+\NC   2 \NC \type {\baselineskip}          \NC \NR
+\NC   3 \NC \type {\parskip}               \NC \NR
+\NC   4 \NC \type {\abovedisplayskip}      \NC \NR
+\NC   5 \NC \type {\belowdisplayskip}      \NC \NR
+\NC   6 \NC \type {\abovedisplayshortskip} \NC \NR
+\NC   7 \NC \type {\belowdisplayshortskip} \NC \NR
+\NC   8 \NC \type {\leftskip}              \NC \NR
+\NC   9 \NC \type {\rightskip}             \NC \NR
+\NC  10 \NC \type {\topskip}               \NC \NR
+\NC  11 \NC \type {\splittopskip}          \NC \NR
+\NC  12 \NC \type {\tabskip}               \NC \NR
+\NC  13 \NC \type {\spaceskip}             \NC \NR
+\NC  14 \NC \type {\xspaceskip}            \NC \NR
+\NC  15 \NC \type {\parfillskip}           \NC \NR
+\NC  16 \NC \type {\thinmuskip}            \NC \NR
+\NC  17 \NC \type {\medmuskip}             \NC \NR
+\NC  18 \NC \type {\thickmuskip}           \NC \NR
+\NC 100 \NC \type {\leaders}               \NC \NR
+\NC 101 \NC \type {\cleaders}              \NC \NR
+\NC 102 \NC \type {\xleaders}              \NC \NR
+\NC 103 \NC \type {\gleaders}              \NC \NR
+\stoptabulate
+
+\subsubsection{kern nodes}
+
+Valid fields: \showfields{kern}\crlf
+Id: \showid{kern}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC \type {0} = from font,
+                                        \type {1} = from \type {\kern} or \type {\/},
+                                        \type {2} = from \type {\accent} \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC kern        \NC number          \NC \NC \NR
+\stoptabulate
+
+
+\subsubsection{penalty nodes}
+
+Valid fields: \showfields{penalty}\crlf
+Id: \showid{penalty}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field  \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype      \NC number          \NC not used \NC \NR
+\NC attr         \NC \syntax{<node>} \NC \NC \NR
+\NC penalty      \NC number          \NC \NC \NR
+\stoptabulate
+
+\subsubsection[glyphnodes]{glyph nodes}
+
+Valid fields: \showfields{glyph}\crlf
+Id: \showid{glyph}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field      \NC \ssbf type      \NC \ssbf explanation \NC \NR
+\NC subtype          \NC number          \NC bitfield \NC \NR
+\NC attr             \NC \syntax{<node>} \NC \NC \NR
+\NC char             \NC number          \NC \NC \NR
+\NC font             \NC number          \NC \NC \NR
+\NC lang             \NC number          \NC \NC \NR
+\NC left             \NC number          \NC \NC \NR
+\NC right            \NC number          \NC \NC \NR
+\NC uchyph           \NC boolean         \NC \NC \NR
+\NC components       \NC \syntax{<node>} \NC pointer to ligature components \NC \NR
+\NC xoffset          \NC number          \NC \NC \NR
+\NC yoffset          \NC number          \NC \NC \NR
+\NC width            \NC number          \NC \NC \NR
+\NC height           \NC number          \NC \NC \NR
+\NC depth            \NC number          \NC \NC \NR
+\NC expansion_factor \NC number          \NC \NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the components field unless you are sure
+its internal link structure is correct, otherwise an error may be result. Valid
+bits for the \type {subtype} field are:
+
+\starttabulate[|c|l|]
+\NC \ssbf bit \NC \bf meaning \NC \NR
+\NC 0 \NC character \NC \NR
+\NC 1 \NC ligature  \NC \NR
+\NC 2 \NC ghost     \NC \NR
+\NC 3 \NC left      \NC \NR
+\NC 4 \NC right     \NC \NR
+\stoptabulate
+
+See \in {section} [charsandglyphs] for a detailed description of the \type
+{subtype} field.
+
+The \type {expansion_factor} has been introduced as part of the separation
+between font- and backend. It is the result of extensive experiments with a more
+efficient implementation of expansion. Early versions of \LUATEX\ already
+replaced multiple instances of fonts in the backend by scaling but contrary to
+\PDFTEX\ in \LUATEX\ we now also got rid of font copies in the frontend and
+replaced them by expansion factors that travel with glyph nodes. Apart from a
+cleaner approach this is also a step towards a better separation between front-
+and backend.
+
+The \type {is_char} function checks if a node is a glyphnode with a subtype still
+less than 256. This function can be used to determine if applying font logic to a
+glyph node makes sense.
+
+\subsubsection{margin_kern nodes}
+
+Valid fields: \showfields{margin_kern}\crlf
+Id: \showid{margin_kern}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC subtype     \NC number          \NC \type {0} = left side,
+                                        \type {1} = right side \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC glyph       \NC \syntax{<node>} \NC \NC \NR
+\stoptabulate
+
+\subsection{Math nodes}
+
+These are the so||called \quote {noad}s and the nodes that are specifically
+associated with math processing. Most of these nodes contain subnodes so that the
+list of possible fields is actually quite small. First, the subnodes:
+
+\subsubsection{Math kernel subnodes}
+
+Many object fields in math mode are either simple characters in a specific family
+or math lists or node lists. There are four associated subnodes that represent
+these cases (in the following node descriptions these are indicated by the word
+\type {<kernel>}).
+
+The \type {next} and \type {prev} fields for these subnodes are unused.
+
+\subsubsubsection{math_char and math_text_char subnodes}
+
+Valid fields: \showfields{math_char}\crlf
+Id: \showid{math_char}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type \NC \bf explanation \NC \NR
+\NC attr \NC \syntax{<node>} \NC \NC \NR
+\NC char \NC number          \NC \NC \NR
+\NC fam  \NC number          \NC \NC \NR
+\stoptabulate
+
+The \type {math_char} is the simplest subnode field, it contains the character
+and family for a single glyph object. The \type {math_text_char} is a special
+case that you will not normally encounter, it arises temporarily during math list
+conversion (its sole function is to suppress a following italic correction).
+
+\subsubsubsection{sub_box and sub_mlist subnodes}
+
+Valid fields: \showfields{sub_box}\crlf
+Id: \showid{sub_box}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type       \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>}\NC \NC \NR
+\NC head        \NC \syntax{<node>}\NC \NC \NR
+\stoptabulate
+
+These two subnode types are used for subsidiary list items. For \type {sub_box},
+the \type {head} points to a \quote {normal} vbox or hbox. For \type {sub_mlist},
+the \type {head} points to a math list that is yet to be converted.
+
+A warning: never assign a node list to the \type {head} field unless you are sure
+its internal link structure is correct, otherwise an error may be result.
+
+\subsubsection{Math delimiter subnode}
+
+There is a fifth subnode type that is used exclusively for delimiter fields. As
+before, the \type {next} and \type {prev} fields are unused.
+
+\subsubsubsection{delim subnodes}
+
+Valid fields: \showfields{delim}\crlf
+Id: \showid{delim}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC\bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC small_char  \NC number          \NC \NC \NR
+\NC small_fam   \NC number          \NC \NC \NR
+\NC large_char  \NC number          \NC \NC \NR
+\NC large_fam   \NC number          \NC \NC \NR
+\stoptabulate
+
+The fields \type {large_char} and \type {large_fam} can be zero, in that case the
+font that is sed for the \type {small_fam} is expected to provide the large
+version as an extension to the \type {small_char}.
+
+\subsubsection{Math core nodes}
+
+First, there are the objects (the \TEX book calls then \quote {atoms}) that are
+associated with the simple math objects: Ord, Op, Bin, Rel, Open, Close, Punct,
+Inner, Over, Under, Vcent. These all have the same fields, and they are combined
+into a single node type with separate subtypes for differentiation.
+
+\subsubsubsection{simple nodes}
+
+Valid fields: \showfields{noad}\crlf
+Id: \showid{noad}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type          \NC \bf explanation \NC \NR
+\NC subtype     \NC number            \NC see below \NC \NR
+\NC attr        \NC \syntax{<node>}   \NC \NC \NR
+\NC nucleus     \NC \syntax{<kernel>} \NC \NC \NR
+\NC sub         \NC \syntax{<kernel>} \NC \NC \NR
+\NC sup         \NC \syntax{<kernel>} \NC \NC \NR
+\stoptabulate
+
+Operators are a bit special because they occupy three subtypes. \type {subtype}.
+
+\starttabulate[|lT|p|]
+\NC \ssbf number \NC \bf node subtype \NC \NR
+\NC  0           \NC Ord \NC \NR
+\NC  1           \NC Op: \type {\displaylimits} \NC \NR
+\NC  2           \NC Op: \type {\limits} \NC \NR
+\NC  3           \NC Op: \type {\nolimits} \NC \NR
+\NC  4           \NC Bin \NC \NR
+\NC  5           \NC Rel \NC \NR
+\NC  6           \NC Open \NC \NR
+\NC  7           \NC Close \NC \NR
+\NC  8           \NC Punct \NC \NR
+\NC  9           \NC Inner \NC \NR
+\NC 10           \NC Under \NC \NR
+\NC 11           \NC Over \NC \NR
+\NC 12           \NC Vcent \NC \NR
+\stoptabulate
+
+\subsubsubsection{accent nodes}
+
+Valid fields: \showfields{accent}\crlf
+Id: \showid{accent}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type          \NC \bf explanation \NC \NR
+\NC subtype     \NC number            \NC the first bit is used for a fixed top
+                                          accent flag (if the \type {accent}
+                                          field is present), the second bit for a
+                                          fixed bottom accent flag (if the \type
+                                          {bot_accent} field is present); example:
+                                          the actual value \type {3} means: do
+                                          not stretch either accent \NC \NR
+\NC attr        \NC \syntax{<node>}   \NC \NC \NR
+\NC nucleus     \NC \syntax{<kernel>} \NC \NC \NR
+\NC sub         \NC \syntax{<kernel>} \NC \NC \NR
+\NC sup         \NC \syntax{<kernel>} \NC \NC \NR
+\NC accent      \NC \syntax{<kernel>} \NC \NC \NR
+\NC bot_accent  \NC \syntax{<kernel>} \NC \NC \NR
+\stoptabulate
+
+\subsubsubsection{style nodes}
+
+Valid fields: \showfields{style}\crlf Id: \showid{style}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type \NC \bf explanation    \NC \NR
+\NC style       \NC string   \NC contains the style \NC \NR
+\stoptabulate
+
+There are eight possibilities for the string value: one of \quote {display},
+\quote {text}, \quote {script}, or \quote {scriptscript}. Each of these can have
+a trailing \type {'} to signify \quote {cramped} styles.
+
+\subsubsubsection{choice nodes}
+
+Valid fields: \showfields{choice}\crlf Id: \showid{choice}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field  \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr         \NC \syntax{<node>} \NC \NC \NR
+\NC display      \NC \syntax{<node>} \NC \NC \NR
+\NC text         \NC \syntax{<node>} \NC \NC \NR
+\NC script       \NC \syntax{<node>} \NC \NC \NR
+\NC scriptscript \NC \syntax{<node>} \NC \NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the display, text, script, or
+scriptscript field unless you are sure its internal link structure is
+correct, otherwise an error may be result.
+
+\subsubsubsection{radical nodes}
+
+Valid fields: \showfields{radical}\crlf Id: \showid{radical}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type          \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>}   \NC \NC \NR
+\NC nucleus     \NC \syntax{<kernel>} \NC \NC \NR
+\NC sub         \NC \syntax{<kernel>} \NC \NC \NR
+\NC sup         \NC \syntax{<kernel>} \NC \NC \NR
+\NC left        \NC \syntax{<delim>}  \NC \NC \NR
+\NC degree      \NC \syntax{<kernel>} \NC
+    Only set by \type {\Uroot}
+\NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the nucleus, sub, sup, left, or degree
+field unless you are sure its internal link structure is correct, otherwise an
+error may be result.
+
+The radical noad is also used for under- and overdelimiters, which is indicated
+by the subtypes:
+
+\starttabulate[|lT|l|]
+\NC 0 \NC \type {\radical}         \NC \NR
+\NC 1 \NC \type {\Uradical}        \NC \NR
+\NC 2 \NC \type {\Uroot}           \NC \NR
+\NC 3 \NC \type {\Uunderdelimiter} \NC \NR
+\NC 4 \NC \type {\Uoverdelimiter}  \NC \NR
+\NC 5 \NC \type {\Udelimiterunder} \NC \NR
+\NC 6 \NC \type {\Udelimiterover}  \NC \NR
+\stoptabulate
+
+\subsubsubsection{fraction nodes}
+
+Valid fields: \showfields{fraction}\crlf
+Id: \showid{fraction}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type          \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>}   \NC \NC \NR
+\NC width       \NC number            \NC \NC \NR
+\NC num         \NC \syntax{<kernel>} \NC \NC \NR
+\NC denom       \NC \syntax{<kernel>} \NC \NC \NR
+\NC left        \NC \syntax{<delim>}  \NC \NC \NR
+\NC right       \NC \syntax{<delim>}  \NC \NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the num, or denom field unless you are
+sure its internal link structure is correct, otherwise an error may be result.
+
+\subsubsubsection{fence nodes}
+
+Valid fields: \showfields{fence}\crlf Id: \showid{fence}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type         \NC \bf explanation \NC \NR
+\NC subtype     \NC number           \NC
+    \type {1} = \type {\left},
+    \type {2} = \type {\middle},
+    \type {3} = \type {\right}
+\NC \NR
+\NC attr        \NC \syntax{<node>}  \NC \NC \NR
+\NC delim       \NC \syntax{<delim>} \NC \NC \NR
+\stoptabulate
+
+\subsection{whatsit nodes}
+
+Whatsit nodes come in many subtypes that you can ask for by running
+\type {node.whatsits()}:
+\startluacode
+    for id, name in table.sortedpairs(node.whatsits()) do
+        context.type(name)
+        context(" (%s), ",id)
+    end
+    context.removeunwantedspaces()
+    context.removepunctuation()
+\stopluacode
+. % period
+
+\subsubsection{open nodes}
+
+Valid fields: \showfields{whatsit,open}\crlf
+Id: \showid{whatsit,open}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC stream      \NC number          \NC \TEX's stream id number \NC \NR
+\NC name        \NC string          \NC file name \NC \NR
+\NC ext         \NC string          \NC file extension \NC \NR
+\NC area        \NC string          \NC file area (this may become obsolete) \NC \NR
+\stoptabulate
+
+\subsubsection{write nodes}
+
+Valid fields: \showfields{whatsit,write}\crlf
+Id: \showid{whatsit,write}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC stream      \NC number          \NC \TEX's stream id number \NC \NR
+\NC data        \NC table           \NC a table representing the token list
+                                        to be written \NC \NR
+\stoptabulate
+
+\subsubsection{close nodes}
+
+Valid fields: \showfields{whatsit,close}\crlf
+Id: \showid{whatsit,close}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC stream      \NC number          \NC \TEX's stream id number \NC \NR
+\stoptabulate
+
+\subsubsection{special nodes}
+
+Valid fields: \showfields{whatsit,special}\crlf
+Id: \showid{whatsit,special}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC data        \NC string          \NC the \type {\special} information \NC \NR
+\stoptabulate
+
+\subsubsection{language nodes}
+
+\LUATEX\ does not have language whatsits any more. All language information is
+already present inside the glyph nodes themselves. This whatsit subtype will be
+removed in the next release.
+
+\subsubsection{local_par nodes}
+
+Valid fields: \showfields{whatsit,local_par}\crlf
+Id: \showid{whatsit,local_par}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field     \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr            \NC \syntax{<node>} \NC \NC \NR
+\NC pen_inter       \NC number          \NC local interline penalty (from \type
+                                            {\localinterlinepenalty}) \NC \NR
+\NC pen_broken      \NC number          \NC local broken penalty (from \type
+                                            {\localbrokenpenalty}) \NC \NR
+\NC dir             \NC string          \NC the direction of this par. see~\in
+                                            [dirnodes] \NC \NR
+\NC box_left        \NC \syntax{<node>} \NC the \type {\localleftbox} \NC \NR
+\NC box_left_width  \NC number          \NC width of the \type {\localleftbox} \NC \NR
+\NC box_right       \NC \syntax{<node>} \NC the \type {\localrightbox}
+\NC \NR
+\NC box_right_width \NC number          \NC width of the \type {\localrightbox} \NC \NR
+\stoptabulate
+
+A warning: never assign a node list to the \type {box_left} or \type {box_right}
+field unless you are sure its internal link structure is correct, otherwise an
+error may be result.
+
+\subsubsection[dirnodes]{dir nodes}
+
+Valid fields: \showfields{whatsit,dir}\crlf
+Id: \showid{whatsit,dir}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC dir         \NC string          \NC the direction (but see below) \NC \NR
+\NC level       \NC number          \NC nesting level of this direction whatsit \NC \NR
+\NC dvi_ptr     \NC number          \NC a saved dvi buffer byte offset \NC \NR
+\NC dir_h       \NC number          \NC a saved dvi position \NC \NR
+\stoptabulate
+
+A note on \type {dir} strings. Direction specifiers are three|-|letter
+combinations of \type {T}, \type {B}, \type {R}, and \type {L}.
+
+These are built up out of three separate items:
+
+\startitemize[packed]
+\startitem
+    the first  is the direction of the \quote{top}   of paragraphs.
+\stopitem
+\startitem
+    the second is the direction of the \quote{start} of lines.
+\stopitem
+\startitem
+    the third  is the direction of the \quote{top}   of glyphs.
+\stopitem
+\stopitemize
+
+However, only four combinations are accepted: \type {TLT}, \type {TRT}, \type
+{RTT}, and \type {LTL}.
+
+Inside actual \type {dir} whatsit nodes, the representation of \type {dir} is not
+a three-letter but a four|-|letter combination. The first character in this case
+is always either \type {+} or \type {-}, indicating whether the value is pushed
+or popped from the direction stack.
+
+\subsubsection{pdf_literal nodes}
+
+Valid fields: \showfields{whatsit,pdf_literal}\crlf
+Id: \showid{whatsit,pdf_literal}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC mode        \NC number          \NC the \quote {mode} setting of this
+                                        literal \NC \NR
+\NC data        \NC string          \NC the \type {\pdfliteral} information \NC \NR
+\stoptabulate
+
+Mode values:
+
+\starttabulate[|lT|p|]
+\NC \ssbf value \NC \ssbf corresponding \type {\pdftex} keyword \NC \NR
+\NC 0           \NC setorigin                                \NC \NR
+\NC 1           \NC page                                     \NC \NR
+\NC 2           \NC direct                                   \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_refobj nodes}
+
+Valid fields: \showfields{whatsit,pdf_refobj}\crlf
+Id: \showid{whatsit,pdf_refobj}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC objnum      \NC number          \NC the referenced \PDF\ object number \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_refxform nodes}
+
+Valid fields: \showfields{whatsit,pdf_refxform}\crlf
+Id: \showid{whatsit,pdf_refxform}.
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC objnum      \NC number          \NC the referenced \PDF\ object number \NC \NR
+\stoptabulate
+
+Be aware that \type {pdf_refxform} nodes have dimensions that are used by \LUATEX.
+
+\subsubsection{pdf_refximage nodes}
+
+Valid fields: \showfields{whatsit,pdf_refximage}\crlf
+Id: \showid{whatsit,pdf_refximage}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC objnum      \NC number          \NC the referenced \PDF\ object number \NC \NR
+\stoptabulate
+
+Be aware that \type {pdf_refximage} nodes have dimensions that are used by
+\LUATEX.
+
+\subsubsection{pdf_annot nodes}
+
+Valid fields: \showfields{whatsit,pdf_annot}\crlf
+Id: \showid{whatsit,pdf_annot}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type       \NC \bf explanation \NC \NR
+\NC attr       \NC \syntax{<node>} \NC \NC \NR
+\NC width      \NC number          \NC \NC \NR
+\NC height     \NC number          \NC \NC \NR
+\NC depth      \NC number          \NC \NC \NR
+\NC objnum     \NC number          \NC the referenced \PDF\ object number \NC \NR
+\NC data       \NC string          \NC the annotation data \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_start_link nodes}
+
+Valid fields: \showfields{whatsit,pdf_start_link}\crlf
+Id: \showid{whatsit,pdf_start_link}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC objnum      \NC number          \NC the referenced \PDF\ object number \NC \NR
+\NC link_attr   \NC table           \NC the link attribute token list \NC \NR
+\NC action      \NC \syntax{<node>} \NC the action to perform \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_end_link nodes}
+
+Valid fields: \showfields{whatsit,pdf_end_link}\crlf
+Id: \showid{whatsit,pdf_end_link}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_dest nodes}
+
+Valid fields: \showfields{whatsit,pdf_dest}\crlf
+Id: \showid{whatsit,pdf_dest}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC named_id    \NC number          \NC is the dest_id a string value? \NC \NR
+\NC dest_id     \NC number          \NC the destination id \NC \NR
+\NC             \NC string          \NC the destination name \NC \NR
+\NC dest_type   \NC number          \NC type of destination \NC \NR
+\NC xyz_zoom    \NC number          \NC \NC \NR
+\NC objnum      \NC number          \NC the \PDF\ object number \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_thread nodes}
+
+Valid fields: \showfields{whatsit,pdf_thread}\crlf
+Id: \showid{whatsit,pdf_thread}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC named_id    \NC number          \NC is the tread_id a string value? \NC \NR
+\NC tread_id    \NC number          \NC the thread id \NC \NR
+\NC             \NC string          \NC the thread name \NC \NR
+\NC thread_attr \NC number          \NC extra thread information \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_start_thread nodes}
+
+Valid fields: \showfields{whatsit,pdf_start_thread}\crlf
+Id: \showid{whatsit,pdf_start_thread}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC width       \NC number          \NC \NC \NR
+\NC height      \NC number          \NC \NC \NR
+\NC depth       \NC number          \NC \NC \NR
+\NC named_id    \NC number          \NC is the tread_id a string value? \NC \NR
+\NC tread_id    \NC number          \NC the thread id \NC \NR
+\NC             \NC string          \NC the thread name \NC \NR
+\NC thread_attr \NC number          \NC extra thread information \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_end_thread nodes}
+
+Valid fields: \showfields{whatsit,pdf_end_thread}\crlf
+Id: \showid{whatsit,pdf_end_thread}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\stoptabulate
+
+\subsubsection{save_pos nodes}
+
+Valid fields: \showfields{whatsit,save_pos}\crlf
+Id: \showid{whatsit,save_pos}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\stoptabulate
+
+\subsubsection{late_lua nodes}
+
+Valid fields: \showfields{whatsit,late_lua}\crlf
+Id: \showid{whatsit,late_lua}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC data        \NC string          \NC data to execute \NC \NR
+\NC string      \NC string          \NC data to execute \NC \NR
+\NC name        \NC string          \NC the name to use for lua error reporting \NC \NR
+\stoptabulate
+
+The difference between \type {data} and \type {string} is that on assignment, the
+\type {data} field is converted to a token list, cf. use as \type {\latelua}. The
+\type {string} version is treated as a literal string.
+
+\subsubsection{pdf_colorstack nodes}
+
+Valid fields: \showfields{whatsit,pdf_colorstack}\crlf
+Id: \showid{whatsit,pdf_colorstack}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC stack       \NC number          \NC colorstack id number \NC \NR
+\NC command     \NC number          \NC command to execute \NC \NR
+\NC data        \NC string          \NC data \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_setmatrix nodes}
+
+Valid fields: \showfields{whatsit,pdf_setmatrix}\crlf
+Id: \showid{whatsit,pdf_setmatrix}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\NC data        \NC string          \NC data \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_save nodes}
+
+Valid fields: \showfields{whatsit,pdf_save}\crlf
+Id: \showid{whatsit,pdf_save}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\stoptabulate
+
+\subsubsection{pdf_restore nodes}
+
+Valid fields: \showfields{whatsit,pdf_restore}\crlf
+Id: \showid{whatsit,pdf_restore}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC \NC \NR
+\stoptabulate
+
+\subsubsection{user_defined nodes}
+
+User|-|defined whatsit nodes can only be created and handled from \LUA\ code. In
+effect, they are an extension to the extension mechanism. The \LUATEX\ engine
+will simply step over such whatsits without ever looking at the contents.
+
+Valid fields: \showfields{whatsit,user_defined}\crlf
+Id: \showid{whatsit,user_defined}
+
+\starttabulate[|lT|l|p|]
+\NC \ssbf field \NC \bf type        \NC  \bf explanation \NC \NR
+\NC attr        \NC \syntax{<node>} \NC  \NC \NR
+\NC user_id     \NC number          \NC id number \NC \NR
+\NC type        \NC number          \NC type of the value \NC \NR
+\NC value       \NC number          \NC \NC \NR
+\NC             \NC string          \NC \NC \NR
+\NC             \NC \syntax{<node>} \NC \NC \NR
+\NC             \NC table           \NC \NC \NR
+\stoptabulate
+
+The \type {type} can have one of five distinct values:
+
+\starttabulate[|lT|p|]
+\NC \ssbf value \NC \bf explanation \NC \NR
+\NC   97        \NC the value is an attribute node list \NC \NR
+\NC  100        \NC the value is a number \NC \NR
+\NC  110        \NC the value is a node list \NC \NR
+\NC  115        \NC the value is a string \NC \NR
+\NC  116        \NC the value is a token list in \LUA\ table form \NC \NR
+\stoptabulate
+
+\section{Two access models}
+
+After doing lots of tests with \LUATEX\ and \LUAJITTEX\, with and without just in
+time compilation enabled, and with and without using ffi, we came to the
+conclusion that userdata prevents a speedup. We also found that the checking of
+metatables as well as assignment comes with overhead that can't be neglected.
+This is normally not really a problem but when processing fonts for more complex
+scripts it could have quite some overhead.
+
+Because the userdata approach has some benefits, this remains the recommended way
+to access nodes. We did several experiments with faster access using this model,
+but eventually settled for the \quote {direct} approach. For code that is proven
+to be okay, one can use this access model that operates on nodes more directly.
+
+Deep down in \TEX\ a node has a number which is an entry in a memory table. In
+fact, this model, where \TEX\ manages memory is real fast and one of the reasons
+why plugging in callbacks that operate on nodes is quite fast. No matter what
+future memory model \LUATEX\ has, an internal reference will always be a simple
+data type (like a number or light userdata in \LUA\ speak). So, if you use the
+direct model, even if you know that you currently deal with numbers, you should
+not depend on that property but treat it an abstraction just like traditional
+nodes. In fact, the fact that we use a simple basic datatype has the penalty that
+less checking can be done, but less checking is also the reason why it's somewhat
+faster. An important aspect is that one cannot mix both methods, but you can cast
+both models.
+
+So our advice is: use the indexed approach when possible and investigate the
+direct one when speed might be an issue. For that reason we also provide the
+\type {get*} and \type {set*} functions in the top level node namespace. There is
+a limited set of getters. When implementing this direct approach the regular
+index by key variant was also optimized, so direct access only makes sense when
+we're accessing nodes millions of times (which happens in some font processing
+for instance).
+
+We're talking mostly of getters because setters are less important. Documents
+have not that many content related nodes and setting many thousands of properties
+is hardly a burden contrary to millions of consultations.
+
+Normally you will access nodes like this:
+
+\starttyping
+local next = current.next
+if next then
+    -- do something
+end
+\stoptyping
+
+Here \type {next} is not a real field, but a virtual one. Accessing it results in
+a metatable method being called. In practice it boils down to looking up the node
+type and based on the node type checking for the field name. In a worst case you
+have a node type that sits at the end of the lookup list and a field that is last
+in the lookup chain. However, in successive versions of \LUATEX\ these lookups
+have been optimized and the most frequently accessed nodes and fields have a
+higher priority.
+
+Because in practice the \type {next} accessor results in a function call, there
+is some overhead involved. The next code does the same and performs a tiny bit
+faster (but not that much because it is still a function call but one that knows
+what to look up).
+
+\starttyping
+local next = node.next(current)
+if next then
+    -- do something
+end
+\stoptyping
+
+There are several such function based accessors now:
+
+\starttabulate[|T|p|]
+\NC getnext    \NC parsing nodelist always involves this one \NC \NR
+\NC getprev    \NC used less but is logical companion to getnext \NC \NR
+\NC getboth    \NC returns the next and prev pointer of a node \NC \NR
+\NC getid      \NC consulted a lot \NC \NR
+\NC getsubtype \NC consulted less but also a topper \NC \NR
+\NC getfont    \NC used a lot in otf handling (glyph nodes are consulted a lot) \NC \NR
+\NC getchar    \NC idem and also in other places \NC \NR
+\NC getdisc    \NC returns the \type {pre}, \type {post} an d\type {replace} fields \NC \NR
+\NC getlist    \NC we often parse nested lists so this is a convenient one too
+                   (only works for hlist and vlist!) \NC \NR
+\NC getleader  \NC comparable to list, seldom used in \TEX\ (but needs frequent consulting
+                   like lists; leaders could have been made a dedicated node type) \NC \NR
+\NC getfield   \NC generic getter, sufficient for the rest (other field names are
+                   often shared so a specific getter makes no sense then) \NC \NR
+\stoptabulate
+
+Some have setter counterparts:
+
+There are several such function based accessors now:
+
+\starttabulate[|T|p|]
+\NC setnext    \NC assigns a value to the next field \NC \NR
+\NC setprev    \NC assigns a value to the prev field \NC \NR
+\NC setboth    \NC assigns a value to the prev and next field \NC \NR
+\NC setlink    \NC links two noded \NC \NR
+\NC setchar    \NC sets the character field \NC \NR
+\NC setdisc    \NC sets the \type {pre}, \type {post} and \type {replace} fields and optionally the
+                   \type {subtype} and \type {penalty} fields \NC \NR  \NC \NR
+\NC getfont    \NC used a lot in otf handling (glyph nodes are consulted a lot) \NC \NR
+\NC getchar    \NC idem and also in other places \NC \NR
+\NC getdisc    \NC returns the \type {pre}, \type {post} an d\type {replace} fields \NC \NR
+\NC getlist    \NC we often parse nested lists so this is a convenient one too
+                   (only works for hlist and vlist!) \NC \NR
+\NC getleader  \NC comparable to list, seldom used in \TEX\ (but needs frequent consulting
+                   like lists; leaders could have been made a dedicated node type) \NC \NR
+\NC getfield   \NC generic getter, sufficient for the rest (other field names are
+                   often shared so a specific getter makes no sense then) \NC \NR
+\stoptabulate
+
+It doesn't make sense to add more. Profiling demonstrated that these fields can
+get accesses way more times than other fields. Even in complex documents, many
+node and fields types never get seen, or seen only a few times. Most functions in
+the \type {node} namespace have a companion in \type {node.direct}, but of course
+not the ones that don't deal with nodes themselves. The following table
+summarized this:
+
+\start \def\yes{$+$} \def\nop{$-$}
+
+\starttabulate[|T|c|c|]
+\HL
+\NC \bf function                \NC \bf node \NC \bf direct \NC \NR
+\HL
+\NC \type {copy_list}            \NC \yes \NC \yes  \NC \NR
+\NC \type {copy}                 \NC \yes \NC \yes  \NC \NR
+\NC \type {count}                \NC \yes \NC \yes  \NC \NR
+\NC \type {current_attr}         \NC \yes \NC \yes  \NC \NR
+\NC \type {dimensions}           \NC \yes \NC \yes  \NC \NR
+\NC \type {do_ligature_n}        \NC \yes \NC \yes  \NC \NR
+\NC \type {effective_glue}       \NC \yes \NC \yes  \NC \NR
+\NC \type {end_of_math}          \NC \yes \NC \yes  \NC \NR
+\NC \type {family_font}          \NC \yes \NC \nop  \NC \NR
+\NC \type {fields}               \NC \yes \NC \nop  \NC \NR
+\NC \type {first_character}      \NC \yes \NC \nop  \NC \NR
+\NC \type {first_glyph}          \NC \yes \NC \yes  \NC \NR
+\NC \type {flush_list}           \NC \yes \NC \yes  \NC \NR
+\NC \type {flush_node}           \NC \yes \NC \yes  \NC \NR
+\NC \type {free}                 \NC \yes \NC \yes  \NC \NR
+\NC \type {getboth}              \NC \yes \NC \yes  \NC \NR
+\NC \type {getbox}               \NC \nop \NC \yes  \NC \NR
+\NC \type {getchar}              \NC \yes \NC \yes  \NC \NR
+\NC \type {getdisc}              \NC \yes \NC \yes  \NC \NR
+\NC \type {getfield}             \NC \yes \NC \yes  \NC \NR
+\NC \type {getfont}              \NC \yes \NC \yes  \NC \NR
+\NC \type {getid}                \NC \yes \NC \yes  \NC \NR
+\NC \type {getleader}            \NC \yes \NC \yes  \NC \NR
+\NC \type {getlist}              \NC \yes \NC \yes  \NC \NR
+\NC \type {getnext}              \NC \yes \NC \yes  \NC \NR
+\NC \type {getprev}              \NC \yes \NC \yes  \NC \NR
+\NC \type {getsubtype}           \NC \yes \NC \yes  \NC \NR
+\NC \type {has_attribute}        \NC \yes \NC \yes  \NC \NR
+\NC \type {has_field}            \NC \yes \NC \yes  \NC \NR
+\NC \type {has_glyph}            \NC \yes \NC \yes  \NC \NR
+\NC \type {hpack}                \NC \yes \NC \yes  \NC \NR
+\NC \type {id}                   \NC \yes \NC \nop  \NC \NR
+\NC \type {insert_after}         \NC \yes \NC \yes  \NC \NR
+\NC \type {insert_before}        \NC \yes \NC \yes  \NC \NR
+\NC \type {is_char}              \NC \yes \NC \yes  \NC \NR
+\NC \type {is_direct}            \NC \nop \NC \yes  \NC \NR
+\NC \type {is_node}              \NC \yes \NC \yes  \NC \NR
+\NC \type {kerning}              \NC \yes \NC \nop  \NC \NR
+\NC \type {last_node}            \NC \yes \NC \yes  \NC \NR
+\NC \type {length}               \NC \yes \NC \yes  \NC \NR
+\NC \type {ligaturing}           \NC \yes \NC \nop  \NC \NR
+\NC \type {mlist_to_hlist}       \NC \yes \NC \nop  \NC \NR
+\NC \type {new}                  \NC \yes \NC \yes  \NC \NR
+\NC \type {next}                 \NC \yes \NC \nop  \NC \NR
+\NC \type {prev}                 \NC \yes \NC \nop  \NC \NR
+\NC \type {protect_glyphs}       \NC \yes \NC \yes  \NC \NR
+\NC \type {protrusion_skippable} \NC \yes \NC \yes  \NC \NR
+\NC \type {remove}               \NC \yes \NC \yes  \NC \NR
+\NC \type {set_attribute}        \NC \yes \NC \yes  \NC \NR
+\NC \type {setboth}              \NC \yes \NC \yes  \NC \NR
+\NC \type {setbox}               \NC \yes \NC \yes  \NC \NR
+\NC \type {setchar}              \NC \yes \NC \yes  \NC \NR
+\NC \type {setdisc}              \NC \yes \NC \yes  \NC \NR
+\NC \type {setfield}             \NC \yes \NC \yes  \NC \NR
+\NC \type {setlink}              \NC \yes \NC \yes  \NC \NR
+\NC \type {setnext}              \NC \yes \NC \yes  \NC \NR
+\NC \type {setprev}              \NC \yes \NC \yes  \NC \NR
+\NC \type {slide}                \NC \yes \NC \yes  \NC \NR
+\NC \type {subtype}              \NC \yes \NC \nop  \NC \NR
+\NC \type {tail}                 \NC \yes \NC \yes  \NC \NR
+\NC \type {todirect}             \NC \yes \NC \yes  \NC \NR
+\NC \type {tonode}               \NC \yes \NC \yes  \NC \NR
+\NC \type {tostring}             \NC \yes \NC \yes  \NC \NR
+\NC \type {traverse_id}          \NC \yes \NC \yes  \NC \NR
+\NC \type {traverse}             \NC \yes \NC \yes  \NC \NR
+\NC \type {types}                \NC \yes \NC \nop  \NC \NR
+\NC \type {type}                 \NC \yes \NC \nop  \NC \NR
+\NC \type {unprotect_glyphs}     \NC \yes \NC \yes  \NC \NR
+\NC \type {unset_attribute}      \NC \yes \NC \yes  \NC \NR
+\NC \type {usedlist}             \NC \yes \NC \yes  \NC \NR
+\NC \type {vpack}                \NC \yes \NC \yes  \NC \NR
+\NC \type {whatsits}             \NC \yes \NC \nop  \NC \NR
+\NC \type {write}                \NC \yes \NC \yes  \NC \NR
+\stoptabulate
+
+\stop
+
+The \type {node.next} and \type {node.prev} functions will stay but for
+consistency there are variants called \type {getnext} and \type {getprev}. We had
+to use \type {get} because \type {node.id} and \type {node.subtype} are already
+taken for providing meta information about nodes. Note: The getters do only basic
+checking for valid keys. You should just stick to the keys mentioned in the
+sections that describe node properties.
+
+\stopchapter
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex-style.tex b/doc/context/sources/general/manuals/luatex/luatex-style.tex
new file mode 100644
index 000000000..4bb4557b0
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-style.tex
@@ -0,0 +1,332 @@
+\startenvironment luatex-style
+
+% I'll clean this up some day.
+
+\usemodule[abr-02]
+
+\setuplayout
+  [height=middle,
+   width=middle,
+   backspace=2cm,
+   topspace=10mm,
+   bottomspace=10mm,
+   header=10mm,
+   footer=10mm,
+   footerdistance=10mm,
+   headerdistance=10mm]
+
+\setuppagenumbering
+  [alternative=doublesided]
+
+\setuptolerance
+  [stretch,tolerant]
+
+\setuptype
+  [lines=hyphenated]
+
+\setuptyping
+  [lines=hyphenated]
+
+\setupitemize
+  [each]
+  [packed]
+
+\setupwhitespace
+  [medium]
+
+\def\|{\string|}
+\def\>{\string>}
+
+\def\showfields#1{\ctxlua
+    {
+        local t = string.split('#1',',')
+        local r = { }
+        for _, a in pairs(node.fields(t[1],t[2])) do
+            if not (a == 'id' or a == 'subtype' or a =='next' or a=='prev') then
+                table.insert(r,'\\type{'.. a .. '}')
+            end
+        end
+        tex.sprint(table.concat(r, ', '))
+    }%
+}
+
+\def\showid#1{\ctxlua
+    {
+        local t = string.split('#1',',')
+        tex.sprint('\\type{'.. node.id(t[1]) .. '}')
+        if t[2] then
+          tex.sprint(', \\type{'.. node.subtype(t[2]) .. '}')
+        end
+    }%
+}
+
+\starttexdefinition unexpanded todo #1
+    \dontleavehmode
+    \startcolor[red]
+        \bf<TODO: #1>
+    \stopcolor
+\stoptexdefinition
+
+\definecolor[blue] [b=.5]
+\definecolor[red]  [r=.5]
+\definecolor[green][g=.5]
+
+\definecolor[maincolor] [b=.5]
+\definecolor[othercolor][r=.5,g=.5]
+
+% \doifmodeelse {atpragma} {
+%
+%   %  \setupbodyfont
+%   %    [lucidaot,10pt]
+%
+%     \setupbodyfont
+%       [dejavu,10pt]
+%
+%     \setuphead [chapter]      [style=\bfd]
+%     \setuphead [section]      [style=\bfb]
+%     \setuphead [subsection]   [style=\bfa]
+%     \setuphead [subsubsection][style=\bf]
+%
+% } {
+%
+%     \definetypeface[mainfacenormal]  [ss][sans] [iwona]       [default]
+%     \definetypeface[mainfacenormal]  [rm][serif][palatino]    [default]
+%     \definetypeface[mainfacenormal]  [tt][mono] [modern]      [default][rscale=1.1]
+%     \definetypeface[mainfacenormal]  [mm][math] [iwona]       [default]
+%
+%     \definetypeface[mainfacemedium]  [ss][sans] [iwona-medium][default]
+%     \definetypeface[mainfacemedium]  [rm][serif][palatino]    [default]
+%     \definetypeface[mainfacemedium]  [tt][mono] [modern]      [default][rscale=1.1]
+%     \definetypeface[mainfacemedium]  [mm][math] [iwona-medium][default]
+%
+%     \setupbodyfont
+%       [mainfacenormal,10pt]
+%
+%     \setuphead [chapter]      [style=\mainfacemedium\bfd]
+%     \setuphead [section]      [style=\mainfacemedium\bfb]
+%     \setuphead [subsection]   [style=\mainfacemedium\bfa]
+%     \setuphead [subsubsection][style=\mainfacemedium\bf]
+%
+% }
+
+\writestatus{luatex manual}{we assume that dejavu math is available}
+
+\setupbodyfont % assumes dejavu-math
+  [dejavu,10pt]
+
+\setuphead [chapter]      [style=\bfd]
+\setuphead [section]      [style=\bfb]
+\setuphead [subsection]   [style=\bfa]
+\setuphead [subsubsection][style=\bf]
+
+\setuphead [chapter]      [color=maincolor]
+\setuphead [section]      [color=maincolor]
+\setuphead [subsection]   [color=maincolor]
+\setuphead [subsubsection][color=maincolor]
+
+\definehead
+  [remark]
+  [subsubsubject]
+
+\setupheadertexts
+  []
+
+\definemixedcolumns
+  [twocolumns]
+  [n=2,
+   balance=yes,
+   before=\blank,
+   after=\blank]
+
+\definemixedcolumns
+  [threecolumns]
+  [twocolumns]
+  [n=3]
+
+\definemixedcolumns
+  [fourcolumns]
+  [threecolumns]
+  [n=4]
+
+\setuptyping
+  [color=maincolor]
+
+\setuptype
+  [color=maincolor]
+
+\definetyping
+  [functioncall]
+
+\startMPdefinitions
+
+    color   luaplanetcolor ; luaplanetcolor := \MPcolor{maincolor} ;
+    color   luaholecolor   ; luaholecolor   := white ;
+    numeric luaextraangle  ; luaextraangle  := 0 ;
+    numeric luaorbitfactor ; luaorbitfactor := .25 ;
+
+    vardef lualogo = image (
+
+        % Graphic design by A. Nakonechnyj. Copyright (c) 1998, All rights reserved.
+
+        save d, r, p ; numeric d, r, p ;
+
+        d := sqrt(2)/4 ; r := 1/4 ; p := r/8 ;
+
+        fill fullcircle scaled 1
+            withcolor luaplanetcolor ;
+        draw fullcircle rotated 40.5 scaled (1+r)
+            dashed evenly scaled p
+            withpen pencircle scaled (p/2)
+            withcolor (luaorbitfactor * luaholecolor) ;
+        fill fullcircle scaled r shifted (d+1/8,d+1/8)
+            rotated luaextraangle
+            withcolor luaplanetcolor ;
+        fill fullcircle scaled r shifted (d-1/8,d-1/8)
+            withcolor luaholecolor   ;
+        luaorbitfactor := .25 ;
+    )  enddef ;
+
+\stopMPdefinitions
+
+\startuseMPgraphic{luapage}
+    StartPage ;
+
+        fill Page withcolor \MPcolor{othercolor} ;
+
+        luaorbitfactor := 1 ;
+        picture p ; p := lualogo xsized (3PaperWidth/5) ;
+        draw p shifted center Page shifted (0,-ypart center ulcorner p) ;
+
+    StopPage ;
+\stopuseMPgraphic
+
+\starttexdefinition luaextraangle
+    % we can also just access the last page and so in mp directly
+    \ctxlua {
+        context(\lastpage == 0 and 0 or \realfolio*360/\lastpage)
+    }
+\stoptexdefinition
+
+\startuseMPgraphic{luanumber}
+    luaextraangle  := \luaextraangle;
+    luaorbitfactor := 0.25 ;
+    picture p ; p := lualogo ;
+    setbounds p to boundingbox fullcircle ;
+    draw p ysized 1cm ;
+\stopuseMPgraphic
+
+\definelayer
+  [page]
+  [width=\paperwidth,
+   height=\paperheight]
+
+\setupbackgrounds
+  [leftpage]
+  [background=page]
+
+\setupbackgrounds
+  [rightpage]
+  [background=page]
+
+\startsetups pagenumber:right
+  \setlayerframed
+    [page]
+    [preset=rightbottom,offset=1cm]
+    [frame=off,height=1cm,offset=overlay]
+    {\useMPgraphic{luanumber}}
+  \setlayerframed
+    [page]
+    [preset=rightbottom,offset=1cm,x=1.5cm]
+    [frame=off,height=1cm,width=1cm,offset=overlay]
+    {\pagenumber}
+  \setlayerframed
+    [page]
+    [preset=rightbottom,offset=1cm,x=2.5cm]
+    [frame=off,height=1cm,offset=overlay]
+    {\getmarking[chapter]}
+\stopsetups
+
+\startsetups pagenumber:left
+  \setlayerframed
+    [page]
+    [preset=leftbottom,offset=1cm,x=2.5cm]
+    [frame=off,height=1cm,offset=overlay]
+    {\getmarking[chapter]}
+  \setlayerframed
+    [page]
+    [preset=leftbottom,offset=1cm,x=1.5cm]
+    [frame=off,height=1cm,width=1cm,offset=overlay]
+    {\pagenumber}
+  \setlayerframed
+    [page]
+    [preset=leftbottom,offset=1cm]
+    [frame=off,height=1cm,offset=overlay]
+    {\useMPgraphic{luanumber}}
+\stopsetups
+
+\unexpanded\def\nonterminal#1>{\mathematics{\langle\hbox{\rm #1}\rangle}}
+
+% taco's brainwave -)
+
+\newcatcodetable\syntaxcodetable
+
+\unexpanded\def\makesyntaxcodetable
+  {\begingroup
+   \catcode`\<=13 \catcode`\|=12
+   \catcode`\!= 0 \catcode`\\=12
+   \savecatcodetable\syntaxcodetable
+   \endgroup}
+
+\makesyntaxcodetable
+
+\unexpanded\def\startsyntax {\begingroup\catcodetable\syntaxcodetable  \dostartsyntax}
+\unexpanded\def\syntax      {\begingroup\catcodetable\syntaxcodetable  \dosyntax}
+           \let\stopsyntax   \relax
+
+\unexpanded\def\syntaxenvbody#1%
+  {\par
+   \tt
+   \startnarrower
+   \maincolor #1
+   \stopnarrower
+   \par}
+
+\unexpanded\def\syntaxbody#1%
+  {\begingroup
+   \maincolor \tt #1%
+   \endgroup}
+
+\bgroup \catcodetable\syntaxcodetable
+
+!gdef!dostartsyntax#1\stopsyntax{!let<!nonterminal!syntaxenvbody{#1}!endgroup}
+!gdef!dosyntax     #1{!let<!nonterminal!syntaxbody{#1}!endgroup}
+
+!egroup
+
+% end of wave
+
+\setupinteraction
+  [state=start,
+   focus=standard,
+   style=,
+   color=,
+   contrastcolor=]
+
+\placebookmarks
+  [chapter,section,subsection]
+
+\setuplist
+  [chapter,section,subsection,subsubsection]
+  [interaction=all]
+
+\setuplist
+  [chapter]
+  [style=bold,
+   color=maincolor]
+
+% Hans doesn't like the bookmarks opening by default so we comment this:
+%
+% \setupinteractionscreen
+%   [option=bookmark]
+
+\stopenvironment
diff --git a/doc/context/sources/general/manuals/luatex/luatex-titlepage.tex b/doc/context/sources/general/manuals/luatex/luatex-titlepage.tex
new file mode 100644
index 000000000..cf40b8eb8
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex-titlepage.tex
@@ -0,0 +1,69 @@
+\environment luatex-style
+\environment luatex-logos
+
+\startcomponent luatex-titlepage
+
+\startstandardmakeup
+
+    \switchtobodyfont
+      [mainfacemedium]
+
+    \definedfont[Bold*default at \the\dimexpr.08\paperheight\relax] \setupinterlinespace
+
+    \setlayer
+      [page]
+      {\useMPgraphic{luapage}}
+
+    \setlayerframed
+      [page]
+      [preset=middletop,
+       voffset=.05\paperheight]
+      [align=middle,
+       foregroundcolor=blue,
+       frame=off]
+      {Lua\TeX\\Reference}
+
+    \definedfont[Bold*default at 24pt] \setupinterlinespace
+
+    \setlayerframed
+      [page]
+      [preset=middletop,
+       voffset=.35\paperheight]
+      [align=middle,
+       foregroundcolor=blue,
+       frame=off]
+      {\doifsomething{\documentvariable{snapshot}}{snapshot \documentvariable{snapshot}}%
+       \doifsomething{\documentvariable{beta}}    {beta     \documentvariable{beta}}}
+
+\stopstandardmakeup
+
+\startstandardmakeup
+
+    \start
+        \raggedleft
+        \definedfont[Bold*default at 48pt]
+        \setupinterlinespace
+        \blue Lua\TeX \endgraf Reference \endgraf Manual \endgraf
+    \stop
+
+    \vfill
+
+    \definedfont[Bold*default at 12pt]
+
+    \starttabulate[|l|l|]
+        \NC copyright \EQ Lua\TeX\ development team \NC \NR
+        \NC more info \EQ www.luatex.org \NC \NR
+        \NC version   \EQ \currentdate \doifsomething{\documentvariable{snapshot}}{(snapshot \documentvariable{snapshot})} \NC \NR
+    \stoptabulate
+
+\stopstandardmakeup
+
+\setupbackgrounds
+  [leftpage]
+  [setups=pagenumber:left]
+
+\setupbackgrounds
+  [rightpage]
+  [setups=pagenumber:right]
+
+\stopcomponent
diff --git a/doc/context/sources/general/manuals/luatex/luatex.tex b/doc/context/sources/general/manuals/luatex/luatex.tex
new file mode 100644
index 000000000..079c34e61
--- /dev/null
+++ b/doc/context/sources/general/manuals/luatex/luatex.tex
@@ -0,0 +1,30 @@
+% \tex vs \type vs \syntax vs. \luatex
+% \em \it \/
+
+\environment luatex-style
+\environment luatex-logos
+
+\dontcomplain
+
+\startdocument
+  [beta=0.80.1]
+
+\component luatex-titlepage
+
+\startfrontmatter
+    \component luatex-contents
+    \component luatex-introduction
+\stopfrontmatter
+
+\startbodymatter
+    \component luatex-enhancements
+    \component luatex-lua
+    \component luatex-languages
+    \component luatex-fonts
+    \component luatex-math
+    \component luatex-nodes
+    \component luatex-libraries
+    \component luatex-modifications
+\stopbodymatter
+
+\stopdocument
diff --git a/scripts/context/lua/mtx-context.lua b/scripts/context/lua/mtx-context.lua
index 3c78532d8..36893f45c 100644
--- a/scripts/context/lua/mtx-context.lua
+++ b/scripts/context/lua/mtx-context.lua
@@ -1028,15 +1028,17 @@ do -- more or less copied from mtx-plain.lua:
             end
         end
         fmtpathspec = string.splitlines(fmtpathspec)[1] or fmtpathspec
-        fmtpathspec = file.splitpath(fmtpathspec)
+        fmtpathspec = fmtpathspec and file.splitpath(fmtpathspec)
         local fmtpath = nil
-        for i=1,#fmtpathspec do
-            local path = fmtpathspec[i]
-            if path ~= "." then
-                dir.makedirs(path)
-                if lfs.isdir(path) and file.is_writable(path) then
-                    fmtpath = path
-                    break
+        if fmtpathspec then
+            for i=1,#fmtpathspec do
+                local path = fmtpathspec[i]
+                if path ~= "." then
+                    dir.makedirs(path)
+                    if lfs.isdir(path) and file.is_writable(path) then
+                        fmtpath = path
+                        break
+                    end
                 end
             end
         end
@@ -1060,6 +1062,17 @@ do -- more or less copied from mtx-plain.lua:
     end
 
     make_mkii_format = function(name,engine)
+
+        -- let the binary sort it out
+
+        os.setenv('SELFAUTOPARENT', "")
+        os.setenv('SELFAUTODIR',    "")
+        os.setenv('SELFAUTOLOC',    "")
+        os.setenv('TEXROOT',        "")
+        os.setenv('TEXOS',          "")
+        os.setenv('TEXMFOS',        "")
+        os.setenv('TEXMFCNF',       "")
+
         make(engine,name)
     end
 
diff --git a/tex/context/base/cont-new.mkiv b/tex/context/base/cont-new.mkiv
index 85019650e..9d763b448 100644
--- a/tex/context/base/cont-new.mkiv
+++ b/tex/context/base/cont-new.mkiv
@@ -11,7 +11,7 @@
 %C therefore copyrighted by \PRAGMA. See mreadme.pdf for
 %C details.
 
-\newcontextversion{2015.10.06 12:49}
+\newcontextversion{2015.10.07 12:03}
 
 %D This file is loaded at runtime, thereby providing an excellent place for
 %D hacks, patches, extensions and new features.
diff --git a/tex/context/base/context-version.pdf b/tex/context/base/context-version.pdf
index 9c67c56ea..4968bcbbe 100644
--- a/tex/context/base/context-version.pdf
+++ b/tex/context/base/context-version.pdf
diff --git a/tex/context/base/context.mkiv b/tex/context/base/context.mkiv
index f529eec31..0fcb7ba97 100644
--- a/tex/context/base/context.mkiv
+++ b/tex/context/base/context.mkiv
@@ -39,7 +39,7 @@
 %D up and the dependencies are more consistent.
 
 \edef\contextformat {\jobname}
-\edef\contextversion{2015.10.06 12:49}
+\edef\contextversion{2015.10.07 12:03}
 \edef\contextkind   {beta}
 
 %D For those who want to use this:
diff --git a/tex/context/base/math-noa.lua b/tex/context/base/math-noa.lua
index cf4db6f02..39c56c59f 100644
--- a/tex/context/base/math-noa.lua
+++ b/tex/context/base/math-noa.lua
@@ -27,6 +27,8 @@ if not modules then modules = { } end modules ['math-noa'] = {
 
 -- todo: most is math_char so we can have simple dedicated loops
 
+-- nota bene: uunderdelimiter uoverdelimiter etc are radicals (we have 5 types)
+
 local utfchar, utfbyte = utf.char, utf.byte
 local formatters = string.formatters
 local sortedhash = table.sortedhash
diff --git a/tex/context/base/math-stc.mkvi b/tex/context/base/math-stc.mkvi
index 80d698c77..164508f05 100644
--- a/tex/context/base/math-stc.mkvi
+++ b/tex/context/base/math-stc.mkvi
@@ -1288,8 +1288,8 @@
 % \limits\normalsuperscript{\box0}\normalsubscript{\box2}}%
 
 % $\Uoverdelimiter \defaultmathfamily "2194 {xxxx}$
-% $\Udelimiterover \defaultmathfamily "2194 {xxxx}$
 % $\Uunderdelimiter\defaultmathfamily "2194 {xxxx}$
+% $\Udelimiterover \defaultmathfamily "2194 {xxxx}$
 % $\Udelimiterunder\defaultmathfamily "2194 {xxxx}$
 % $\Udelimiterover \defaultmathfamily "219A {\Udelimiterunder \defaultmathfamily "219B {xxxx}}$
 
diff --git a/tex/context/base/node-ini.lua b/tex/context/base/node-ini.lua
index 02d4c7a3f..87d97c648 100644
--- a/tex/context/base/node-ini.lua
+++ b/tex/context/base/node-ini.lua
@@ -108,6 +108,16 @@ local noadcodes = allocate { -- simple nodes
     [12] = "vcenter",
 }
 
+local radicalcodes = allocate {
+    [0] = "radical",
+    [1] = "uradical",
+    [2] = "uroot",
+    [3] = "uunderdelimiter",
+    [4] = "uoverdelimiter",
+    [5] = "udelimiterunder",
+    [6] = "udelimiterover",
+}
+
 local listcodes = allocate {
     [ 0] = "unknown",
     [ 1] = "line",
@@ -186,6 +196,7 @@ local whatcodes = simplified(node.whatsits())
 
 skipcodes    = allocate(swapped(skipcodes,skipcodes))
 noadcodes    = allocate(swapped(noadcodes,noadcodes))
+radicalcodes = allocate(swapped(radicalcodes,radicalcodes))
 nodecodes    = allocate(swapped(nodecodes,nodecodes))
 whatcodes    = allocate(swapped(whatcodes,whatcodes))
 listcodes    = allocate(swapped(listcodes,listcodes))
diff --git a/tex/context/base/status-files.pdf b/tex/context/base/status-files.pdf
index 2609ba4d4..ce81d5ce7 100644
--- a/tex/context/base/status-files.pdf
+++ b/tex/context/base/status-files.pdf
diff --git a/tex/context/base/status-lua.pdf b/tex/context/base/status-lua.pdf
index d7249ac2d..23f2f42b0 100644
--- a/tex/context/base/status-lua.pdf
+++ b/tex/context/base/status-lua.pdf
diff --git a/tex/context/base/syst-ini.mkiv b/tex/context/base/syst-ini.mkiv
index 8633e3272..eef4387cb 100644
--- a/tex/context/base/syst-ini.mkiv
+++ b/tex/context/base/syst-ini.mkiv
@@ -1084,10 +1084,9 @@
     \matheqnogapstep  \zerocount
 \fi
 
-%D New primitives:
+%D New primitive:
 
 \ifdefined\hyphenationmin \else \newcount\hyphenationmin \fi
-\ifdefined\discpenalty    \else \newcount\discpenalty    \fi
 
 %D While cleaning this code up a bit I was listening to Heather Nova's \CD\ Redbird.
 %D The first song on that \CD\ ends with a few lines suitable for ending this
diff --git a/tex/generic/context/luatex/luatex-fonts-merged.lua b/tex/generic/context/luatex/luatex-fonts-merged.lua
index ddbfffb17..118fde56b 100644
--- a/tex/generic/context/luatex/luatex-fonts-merged.lua
+++ b/tex/generic/context/luatex/luatex-fonts-merged.lua
@@ -1,6 +1,6 @@
 -- merged file : luatex-fonts-merged.lua
 -- parent file : luatex-fonts.lua
--- merge date  : 10/06/15 12:49:17
+-- merge date  : 10/07/15 12:03:10
 
 do -- begin closure to overcome local limits and interference