From 7b271baae19db1528fbe6621bdf50af89a5a336b Mon Sep 17 00:00:00 2001
From: Hans Hagen <pragma@wxs.nl>
Date: Fri, 22 Feb 2019 20:29:46 +0100
Subject: 2019-02-22 19:43:00

---
 .../general/manuals/luatex/luatex-enhancements.tex | 1052 ++++++++++++++------
 1 file changed, 752 insertions(+), 300 deletions(-)

(limited to 'doc/context/sources/general/manuals/luatex/luatex-enhancements.tex')

diff --git a/doc/context/sources/general/manuals/luatex/luatex-enhancements.tex b/doc/context/sources/general/manuals/luatex/luatex-enhancements.tex
index e0119bf7e..b81e1dbda 100644
--- a/doc/context/sources/general/manuals/luatex/luatex-enhancements.tex
+++ b/doc/context/sources/general/manuals/luatex/luatex-enhancements.tex
@@ -1,22 +1,23 @@
 % language=uk
 
 \environment luatex-style
-\environment luatex-logos
 
 \startcomponent luatex-enhancements
 
 \startchapter[reference=enhancements,title={Basic \TEX\ enhancements}]
 
-\section{Introduction}
+\startsection[title={Introduction}]
+
+\startsubsection[title={Primitive behaviour}]
 
 From day one, \LUATEX\ has offered extra features compared to the superset of
-\PDFTEX\ and \ALEPH. This has not been limited to the possibility to execute
-\LUA\ code via \type {\directlua}, but \LUATEX\ also adds functionality via new
-\TEX|-|side primitives or extensions to existing ones.
+\PDFTEX, which includes \ETEX, and \ALEPH. This has not been limited to the
+possibility to execute \LUA\ code via \prm {directlua}, but \LUATEX\ also adds
+functionality via new \TEX|-|side primitives or extensions to existing ones.
 
 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
+\prm {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:
@@ -25,7 +26,7 @@ file:
 \directlua { tex.enableprimitives('',tex.extraprimitives()) }
 \stoptyping
 
-But be aware that the curly braces may not have the proper \type {\catcode}
+But be aware that the curly braces may not have the proper \prm {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:
 
@@ -36,44 +37,62 @@ it may be needed to put these assignments before the above line:
 
 More fine|-|grained primitives control is possible and 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.
+assumes that you have executed the \prm {directlua} command as given above.
 
 The startup behaviour documented above is considered stable in the sense that
 there will not be backward|-|incompatible changes any more. We have 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 only
-have the \type {tex}, \type {etex} and \type {luatex} sets left.
+rather generic \PDFTEX\ primitives to core \LUATEX\ ones, and the few that we
+inherited from \ALEPH\ (\OMEGA) are also promoted. Effectively this means that we
+now only have the \type {tex}, \type {etex} and \type {luatex} sets left.
 
 In \in {Chapter} [modifications] we discuss several primitives that are derived
 from \PDFTEX\ and \ALEPH\ (\OMEGA). Here we stick to real new ones. In the
 chapters on fonts and math we discuss a few more new ones.
 
-\section{Version information}
+\stopsubsection
+
+\startsubsection[title={Version information}]
 
-\subsection {\type {\luatexbanner}, \type {\luatexversion} and \type {\luatexrevision}}
+\startsubsubsection[title={\lpr {luatexbanner}, \lpr {luatexversion} and \lpr {luatexrevision}}]
+
+\topicindex{version}
+\topicindex{banner}
 
 There are three new primitives to test the version of \LUATEX:
 
-\starttabulate[|l|pl|pl|]
-\BC primitive               \BC explanation                               \BC 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
+\unexpanded\def\VersionHack#1% otherwise different luatex and luajittex runs
+  {\ctxlua{%
+     local banner = "\luatexbanner"
+     local banner = string.match(banner,"(.+)\letterpercent(") or banner
+     context(string.gsub(banner ,"jit",""))%
+  }}
+
+\starttabulate[|l|l|pl|]
+\DB primitive             \BC value
+                          \BC explanation \NC \NR
+\TB
+\NC \lpr {luatexbanner}   \NC \VersionHack{\luatexbanner}
+                          \NC the banner reported on the command line \NC \NR
+\NC \lpr {luatexversion}  \NC \the\luatexversion
+                          \NC a combination of major and minor number \NC \NR
+\NC \lpr {luatexrevision} \NC \luatexrevision
+                          \NC the revision number, the current value is \NC \NR
+\LL
 \stoptabulate
 
 The official \LUATEX\ version is defined as follows:
 
 \startitemize
 \startitem
-    The major version is the integer result of \type {\luatexversion} divided by
+    The major version is the integer result of \lpr {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.
+    its use with \prm {the} depending on the context.
 \stopitem
 \startitem
-    The minor version is the two-digit result of \type {\luatexversion} modulo 100.
+    The minor version is the two|-|digit result of \lpr {luatexversion} modulo 100.
 \stopitem
 \startitem
-    The revision is the given by \type {\luatexrevision}. This primitive expands to
+    The revision is reported by \lpr {luatexrevision}. This primitive expands to
     a positive integer.
 \stopitem
 \startitem
@@ -82,16 +101,28 @@ The official \LUATEX\ version is defined as follows:
 \stopitem
 \stopitemize
 
-\subsection{\type {\formatname}}
+\stopsubsubsection
+
+\startsubsubsection[title={\lpr {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
+\topicindex{format}
+
+The \lpr {formatname} syntax is identical to \prm {jobname}. In \INITEX, the
+expansion is empty. Otherwise, the expansion is the value that \prm {jobname} had
 during the \INITEX\ run that dumped the currently loaded format. You can use this
 token list to provide your own version info.
 
-\section{\UNICODE\ text support}
+\stopsubsubsection
+
+\stopsubsection
+
+\stopsection
 
-\subsection {Extended ranges}
+\startsection[title={\UNICODE\ text support}]
+
+\startsubsection[title={Extended ranges}]
+
+\topicindex{\UNICODE}
 
 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
@@ -101,22 +132,25 @@ 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 up to the user: subtypes larger than 255 indicate that
+changed in \LUA\ it is up to the user. Subtypes larger than 255 indicate that
 font processing has happened.
 
 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
+to accommodate for a larger range of acceptable numbers. For instance, \prm
+{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}.
+engines. The affected commands with an altered initial (left of the equal sign)
+or secondary (right of the equal sign) value are: \prm {char}, \prm {lccode},
+\prm {uccode}, \lpr {hjcode}, \prm {catcode}, \prm {sfcode}, \lpr {efcode}, \lpr
+{lpcode}, \lpr {rpcode}, \prm {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.
+callback. This will be explained in \in {section} [iocallback]. Normalization of
+the \UNICODE\ input is on purpose not built|-|in and can be handled by a macro
+package during callback processing. We have made some practical choices and the
+user has to live with those.
 
 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
@@ -129,58 +163,106 @@ are considered \quote {safe} and therefore printed as|-|is. You can disable
 escaping with \type {texio.setescape(false)} in which case you get the normal
 characters on the console.
 
-Normalization of the \UNICODE\ input can be handled by a macro package during
-callback processing (this will be explained in \in {section} [iocallback]).
+\stopsubsection
 
-\subsection{\type {\Uchar}}
+\startsubsection[title={\lpr {Uchar}}]
 
-The expandable command \type {\Uchar} reads a number between~0 and $1{,}114{,}111$
+\topicindex{\UNICODE}
+
+The expandable command \lpr {Uchar} reads a number between~0 and $1{,}114{,}111$
 and expands to the associated \UNICODE\ character.
 
-\section{Extended tables}
+\stopsubsection
+
+\startsubsection[title={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
+\startlines
+\prm {count}
+\prm {dimen}
+\prm {skip}
+\prm {muskip}
+\prm {marks}
+\prm {toks}
+\prm {countdef}
+\prm {dimendef}
+\prm {skipdef}
+\prm {muskipdef}
+\prm {toksdef}
+\prm {insert}
+\prm {box}
+\prm {unhbox}
+\prm {unvbox}
+\prm {copy}
+\prm {unhcopy}
+\prm {unvcopy}
+\prm {wd}
+\prm {ht}
+\prm {dp}
+\prm {setbox}
+\prm {vsplit}
+\stoplines
 \stopfourcolumns
 
 Because font memory management has been rewritten, character properties in fonts
-are no longer shared among fonts instances that originate from the same metric
-file.
+are no longer shared among font instances that originate from the same metric
+file. Of course we share fonts in the backend when possible so that the resulting
+\PDF\ file is as efficient as possible, but for instance also expansion and
+protrusion no longer use copies as in \PDFTEX.
+
+\stopsubsection
 
-\section{Attributes}
+\stopsection
 
-\subsection{Attribute registers}
+\startsection[title={Attributes}]
+
+\startsubsection[title={Nodes}]
+
+\topicindex {nodes}
+
+When \TEX\ reads input it will interpret the stream according to the properties
+of the characters. Some signal a macro name and trigger expansion, others open
+and close groups, trigger math mode, etc. What's left over becomes the typeset
+text. Internally we get linked list of nodes. Characters become \nod {glyph}
+nodes that have for instance a \type {font} and \type {char} property and \typ
+{\kern 10pt} becomes a \nod {kern} node with a \type {width} property. Spaces are
+alien to \TEX\ as they are turned into \nod {glue} nodes. So, a simple paragraph
+is mostly a mix of sequences of \nod {glyph} nodes (words) and \nod {glue} nodes
+(spaces).
+
+The sequences of characters at some point are extended with \nod {disc} nodes
+that relate to hyphenation. After that font logic can be applied and we get a
+list where some characters can be replaced, for instance multiple characters can
+become one ligature, and font kerns can be injected. This is driven by the
+font properties.
+
+Boxes (like \prm {hbox} and \prm {vbox}) become \nod {hlist} or \nod {vlist}
+nodes with \type {width}, \type {height}, \type {depth} and \type {shift}
+properties and a pointer \type {list} to its actual content. Boxes can be
+constructed explicitly or can be the result of subprocesses. For instance, when
+lines are broken into paragraphs, the lines are a linked list of \nod {hlist}
+nodes.
+
+So, to summarize: all that you enter as content eventually becomes a node, often
+as part of a (nested) list structure. They have a relative small memory footprint
+and carry only the minimal amount of information needed. In traditional \TEX\ a
+character node only held the font and slot number, in \LUATEX\ we also store some
+language related information, the expansion factor, etc. Now that we have access
+to these nodes from \LUA\ it makes sense to be able to carry more information
+with an node and this is where attributes kick in.
+
+\stopsubsection
+
+\startsubsection[title={Attribute registers}]
+
+\topicindex {attributes}
 
 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.
+\prm {the} etc.\ just like the normal \prm {count} registers.
 
 \startsyntax
 \attribute <16-bit number> <optional equals> <32-bit number>!crlf
@@ -202,13 +284,22 @@ attached to all nodes created in their scope. These can then be queried from any
 attributes for node list processing from \LUA\ is given in~\in {chapter}[nodes].
 
 Attributes are stored in a sorted (sparse) linked list that are shared when
-possible. This permits efficient testing and updating.
+possible. This permits efficient testing and updating. You can define many
+thousands of attributes but normally such a large number makes no sense and is
+also not that efficient because each node carries a (possibly shared) link to a
+list of currently set attributes. But they are a convenient extension and one of
+the first extensions we implemented in \LUATEX.
+
+\stopsubsection
 
-\subsection{Box attributes}
+\startsubsection[title={Box attributes}]
+
+\topicindex {attributes}
+\topicindex {boxes}
 
 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
+building, the individual line boxes are created after the \prm {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.
@@ -229,28 +320,64 @@ incompatibility is mostly due to the fact that separate specials and literals ar
 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:
+{hbox}, \type {vbox} or \type {vtop} by the use of the keyword \type {attr}. The
+\type {attr} keyword(s) should come before a \type {to} or \type {spread}, if
+that is also specified. An example is:
 
-\starttyping
-\attribute2=5
+\startbuffer[tex]
+\attribute997=123
+\attribute998=456
 \setbox0=\hbox {Hello}
-\setbox2=\hbox attr1=12 attr2=-"7FFFFFFF{Hello}
-\stoptyping
+\setbox2=\hbox attr 999 = 789 attr 998 = -"7FFFFFFF{Hello}
+\stopbuffer
+
+\startbuffer[lua]
+  for b=0,2,2 do
+    for a=997, 999 do
+      tex.sprint("box ", b, " : attr ",a," : ",tostring(tex.box[b]     [a]))
+      tex.sprint("\\quad\\quad")
+      tex.sprint("list ",b, " : attr ",a," : ",tostring(tex.box[b].list[a]))
+      tex.sprint("\\par")
+    end
+  end
+\stopbuffer
+
+\typebuffer[tex]
+
+Box 0 now has attributes 997 and 998 set while box 2 has attributes 997 and 999
+set while the nodes inside that box will all have attributes 997 and 998 set.
+Assigning the maximum negative value causes an attribute to be ignored.
+
+To give you an idea of what this means at the \LUA\ end, take the following
+code:
+
+\typebuffer[lua]
 
-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.
+Later we will see that you can access properties of a node. The boxes here are so
+called \nod {hlist} nodes that have a field \type {list} that points to the
+content. Because the attributes are a list themselves you can access them by
+indexing the node (here we do that with \type {[a]}. Running this snippet gives:
 
-The \type {attr} keyword(s) should come before a \type {to} or \type {spread}, if
-that is also specified.
+\start
+    \getbuffer[tex]
+    \startpacked \tt
+        \ctxluabuffer[lua]
+    \stoppacked
+\stop
 
-\section{\LUA\ related primitives}
+Because some values are not set we need to apply the \type {tostring} function
+here so that we get the word \type {nil}.
 
-\subsection{\type {\directlua}}
+\stopsubsection
+
+\stopsection
+
+\startsection[title={\LUA\ related primitives}]
+
+\startsubsection[title={\prm {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
+The primitive \prm {directlua} is used to execute \LUA\ code immediately. The
 syntax is
 
 \startsyntax
@@ -261,10 +388,10 @@ syntax is
 The \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.
+displayed using \type {\the\toks}. On the \LUA\ side, each \prm {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
@@ -281,15 +408,16 @@ say:
 \stoptyping
 
 Then \LUA\ line comments can be used, since \TEX\ does not replace line endings
-with spaces.
+with spaces. Of course such an approach depends on the macro package that you
+use.
 
-Likewise, the \syntax {<16-bit number>} designates a name of a \LUA\ chunk and is
+The \syntax {<16-bit number>} designates a name of a \LUA\ chunk and is
 taken from the \type {lua.name} array (see the documentation of the \type {lua}
 table further in this manual). When a chunk name starts with a \type {@} it will
 be displayed as a file name. This is a side effect of the way \LUA\ implements
 error handling.
 
-The \type {\directlua} command is expandable. Since it passes \LUA\ code to the
+The \prm {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
@@ -320,10 +448,10 @@ will result in
 
 \getbuffer
 
-Note that the expansion of \type {\directlua} is a sequence of characters, not of
+Note that the expansion of \prm {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
+\ETEX's \prm {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
@@ -337,15 +465,14 @@ 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 behaviour documented in the above subsection is considered stable in the sense
-that there will not be backward-incompatible changes any more.
+\stopsubsection
 
-\subsection{\type {\latelua}}
+\startsubsection[title={\lpr {latelua} and \lpr {lateluafunction}}]
 
-Contrary to \type {\directlua}, \type {\latelua} stores \LUA\ code in a whatsit
+Contrary to \prm {directlua}, \lpr {latelua} stores \LUA\ code in a whatsit
 that will be processed at the time of shipping out. Its intended use is a cross
-between \PDF\ literals (often available as \type {\pdfliteral}) and the
-traditional \TEX\ extension \type {\write}. Within the \LUA\ code you can print
+between \PDF\ literals (often available as \orm {pdfliteral}) and the
+traditional \TEX\ extension \prm {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\ \IO\
 routines.
@@ -356,12 +483,19 @@ routines.
 \stopsyntax
 
 Expansion of macros 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 \PDF\ page literals. The \syntax
+before the whatsit is executed (like in \prm {write}). With regard to \PDF\
+output stream \lpr {latelua} behaves as \PDF\ page literals. The \syntax
 {name <general text>} and \syntax {<16-bit number>} behave in the same way as
-they do for \type {\directlua}
+they do for \prm {directlua}.
+
+The \lpr {lateluafunction} primitive takes a number and is similar to \lpr
+{luafunction} but gets delated to shipout time. It's just there for completeness.
+
+\stopsubsection
+
+\startsubsection[title={\lpr {luaescapestring}}]
 
-\subsection{\type {\luaescapestring}}
+\topicindex {escaping}
 
 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,
@@ -375,23 +509,24 @@ sequence is fully expanded.
 \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}:
+differences between \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} and \type {\luafunctioncall}}
+\stopsubsection
 
-The \type {\directlua} commands involves tokenization of its argument (after
+\startsubsection[title={\lpr {luafunction}, \lpr {luafunctioncall} and \lpr {luadef}}]
+
+The \prm {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 of
-thousands of times, it can become noticeable. For this reason there is a variant
-call available: \type {\luafunction}. This command is used as follows:
+called. The overhead is rather small but when you have millions of calls it can
+have some impact. For this reason there is a variant call available: \lpr
+{luafunction}. This command is used as follows:
 
 \starttyping
 \directlua {
@@ -417,73 +552,117 @@ in the following example the number \type {8} gets typeset.
 }
 \stoptyping
 
-The \type {\luafunctioncall} primitive does the same but is unexpandable, for instance
-in an \type {\edef}.
+The \lpr {luafunctioncall} primitive does the same but is unexpandable, for
+instance in an \prm {edef}. In addition \LUATEX\ provides a definer:
+
+\starttyping
+                 \luadef\MyFunctionA 1
+          \global\luadef\MyFunctionB 2
+\protected\global\luadef\MyFunctionC 3
+\stoptyping
 
-\section {Alignments}
+You should really use these commands with care. Some references get stored in
+tokens and assume that the function is available when that token expands. On the
+other hand, as we have tested this functionality in relative complex situations
+normal usage should not give problems.
 
-\subsection{\tex {alignmark}}
+\stopsubsection
 
-This primitive duplicates the functionality of \type {#} inside alignment
-preambles.
+\startsubsection[title={\lpr {luabytecode} and \lpr {luabytecodecall}}]
 
-\subsection{\tex {aligntab}}
+Analogue to the function callers discussed in the previous section we have byte
+code callers. Again the call variant is unexpandable.
+
+\starttyping
+\directlua {
+    lua.bytecode[9998] = function(s)
+        tex.sprint(s*token.scan_int())
+    end
+    lua.bytecode[5555] = function(s)
+        tex.sprint(s*token.scan_dimen())
+    end
+}
+\stoptyping
+
+This works with:
+
+\starttyping
+\luabytecode    9998 5  \luabytecode    5555 5sp
+\luabytecodecall9998 5  \luabytecodecall5555 5sp
+\stoptyping
 
-This primitive duplicates the functionality of \type {&} inside alignments and
-preambles.
+The variable \type {s} in the code is the number of the byte code register that
+can be used for diagnostic purposes. The advantage of bytecode registers over
+function calls is that they are stored in the format (but without upvalues).
 
-\section{Catcode tables}
+\stopsubsection
+
+\stopsection
+
+\startsection[title={Catcode tables}]
+
+\startsubsection[title={Catcodes}]
+
+\topicindex {catcodes}
 
 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 behaviour
 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.
+from any other catcode table, and its contents is stored and retrieved from the
+format file.
 
-\subsection{\type {\catcodetable}}
+\stopsubsection
+
+\startsubsection[title={\lpr {catcodetable}}]
 
 \startsyntax
 \catcodetable <15-bit number>
 \stopsyntax
 
-The primitive \type {\catcodetable} switches to a different catcode table. Such a
+The primitive \lpr {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}}
+\stopsubsection
+
+\startsubsection[title={\lpr {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|]
-\NC  0 \NC \tttf \letterbackslash       \NC         \NC \type {escape}       \NC\NR
-\NC  5 \NC \tttf \letterhat\letterhat M \NC return  \NC \type {car_ret}      \NC\NR
-\NC  9 \NC \tttf \letterhat\letterhat @ \NC null    \NC \type {ignore}       \NC\NR
-\NC 10 \NC \tttf <space>                \NC space   \NC \type {spacer}       \NC\NR
-\NC 11 \NC {\tttf a} \endash\ {\tttf z} \NC         \NC \type {letter}       \NC\NR
-\NC 11 \NC {\tttf A} \endash\ {\tttf Z} \NC         \NC \type {letter}       \NC\NR
-\NC 12 \NC everything else              \NC         \NC \type {other}        \NC\NR
-\NC 14 \NC \tttf \letterpercent         \NC         \NC \type {comment}      \NC\NR
-\NC 15 \NC \tttf \letterhat\letterhat ? \NC delete  \NC \type {invalid_char} \NC\NR
+The primitive \lpr {initcatcodetable} creates a new table with catcodes
+identical to those defined by \INITEX. 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. The
+initial values are:
+
+\starttabulate[|c|c|l|l|]
+\DB catcode \BC character               \BC equivalent \BC category          \NC \NR
+\TB
+\NC  0 \NC \tttf \letterbackslash       \NC         \NC \type {escape}       \NC \NR
+\NC  5 \NC \tttf \letterhat\letterhat M \NC return  \NC \type {car_ret}      \NC \NR
+\NC  9 \NC \tttf \letterhat\letterhat @ \NC null    \NC \type {ignore}       \NC \NR
+\NC 10 \NC \tttf <space>                \NC space   \NC \type {spacer}       \NC \NR
+\NC 11 \NC {\tttf a} \endash\ {\tttf z} \NC         \NC \type {letter}       \NC \NR
+\NC 11 \NC {\tttf A} \endash\ {\tttf Z} \NC         \NC \type {letter}       \NC \NR
+\NC 12 \NC everything else              \NC         \NC \type {other}        \NC \NR
+\NC 14 \NC \tttf \letterpercent         \NC         \NC \type {comment}      \NC \NR
+\NC 15 \NC \tttf \letterhat\letterhat ? \NC delete  \NC \type {invalid_char} \NC \NR
+\LL
 \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.
+\stopsubsection
 
-\subsection{\type {\savecatcodetable}}
+\startsubsection[title={\lpr {savecatcodetable}}]
 
 \startsyntax
 \savecatcodetable <15-bit number>
 \stopsyntax
 
-\type {\savecatcodetable} copies the current set of catcodes to a new table with
+\lpr {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.
 
@@ -491,55 +670,78 @@ 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}
+\stopsubsection
+
+\stopsection
 
-\subsection{\type {\suppressfontnotfounderror}}
+\startsection[title={Suppressing errors}]
+
+\startsubsection[title={\lpr {suppressfontnotfounderror}}]
+
+\topicindex {errors}
+
+If this 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 \prm {ifx} equal to \prm
+{nullfont}, so that it can be tested against that without bothering the user.
 
 \startsyntax
 \suppressfontnotfounderror = 1
 \stopsyntax
 
-If this 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.
+\stopsubsection
+
+\startsubsection[title={\lpr {suppresslongerror}}]
 
-\subsection{\type {\suppresslongerror}}
+\topicindex {errors}
+
+If this integer parameter is non|-|zero, then \LUATEX\ will not complain about
+\prm {par} commands encountered in contexts where that is normally prohibited
+(most prominently in the arguments of macros not defined as \prm {long}).
 
 \startsyntax
 \suppresslongerror = 1
 \stopsyntax
 
-If this 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).
+\stopsubsection
 
-\subsection{\type {\suppressifcsnameerror}}
+\startsubsection[title={\lpr {suppressifcsnameerror}}]
 
-\startsyntax
-\suppressifcsnameerror = 1
-\stopsyntax
+\topicindex {errors}
 
 If this integer parameter is non|-|zero, then \LUATEX\ will not complain about
-non-expandable commands appearing in the middle of a \type {\ifcsname} expansion.
+non-expandable commands appearing in the middle of a \prm {ifcsname} expansion.
 Instead, it will keep getting expanded tokens from the input until it encounters
-an \type {\endcsname} command. If the input expansion is unbalanced with respect
-to \type {\csname} \ldots \type {\endcsname} pairs, the \LUATEX\ process may hang
+an \prm {endcsname} command. If the input expansion is unbalanced with respect
+to \prm {csname} \ldots \prm {endcsname} pairs, the \LUATEX\ process may hang
 indefinitely.
 
-\subsection{\type {\suppressoutererror}}
-
 \startsyntax
-\suppressoutererror = 1
+\suppressifcsnameerror = 1
 \stopsyntax
 
+\stopsubsection
+
+\startsubsection[title={\lpr {suppressoutererror}}]
+
+\topicindex {errors}
+
 If this new integer parameter is non|-|zero, then \LUATEX\ will not complain
-about \type {\outer} commands encountered in contexts where that is normally
+about \prm {outer} commands encountered in contexts where that is normally
 prohibited.
 
-\subsection{\type {\suppressmathparerror}}
+\startsyntax
+\suppressoutererror = 1
+\stopsyntax
+
+\stopsubsection
+
+\startsubsection[title={\lpr {suppressmathparerror}}]
+
+\topicindex {errors}
+\topicindex {math}
 
-The following setting will permit \type {\par} tokens in a math formula:
+The following setting will permit \prm {par} tokens in a math formula:
 
 \startsyntax
 \suppressmathparerror = 1
@@ -553,41 +755,30 @@ $ x + 1 =
 a $
 \stoptyping
 
-\subsection{\type {\suppressprimitiveerror}}
+\stopsubsection
+
+\startsubsection[title={\lpr {suppressprimitiveerror}}]
+
+\topicindex {errors}
+\topicindex {primitives}
 
 When set to a non|-|zero value the following command will not issue an error:
 
-\starttyping
+\startsyntax
 \suppressprimitiveerror = 1
 
 \primitive\notaprimitive
-\stoptyping
-
-\section {Math}
-
-\subsection{Extensions}
+\stopsyntax
 
-We will cover math in its own chapter because not only the font subsystem and
-spacing model have been enhanced (thereby introducing many new primitives) but
-also because some more control has been added to existing functionality.
+\stopsubsection
 
-\subsection{\type {\matheqnogapstep}}
+\stopsection
 
-By default \TEX\ will add one quad between the equation and the number. This is
-hard coded. A new primitive can control this:
+\startsection[title={Fonts}]
 
-\startsyntax
-\matheqnogapstep = 1000
-\stopsyntax
+\startsubsection[title={Font syntax}]
 
-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{Fonts}
-
-\subsection{Font syntax}
+\topicindex {fonts}
 
 \LUATEX\ will accept a braced argument as a font name:
 
@@ -598,20 +789,26 @@ is divided by 1000 which is the usual way to mimmick floating point factors in
 This allows for embedded spaces, without the need for double quotes. Macro
 expansion takes place inside the argument.
 
-\subsection{\type {\fontid}}
+\stopsubsection
+
+\startsubsection[title={\lpr {fontid} and \lpr {setfontid}}]
 
 \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
+prefix with \prm {number} (and using \prm {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
+\starttabulate[|l|c|c|]
+\DB style \BC command \BC font id \NC \NR
+\TB
+\NC normal      \NC \type {\tf} \NC \bf \fontid\font \NC \NR
+\NC bold        \NC \type {\bf} \NC \bf \fontid\font \NC \NR
+\NC italic      \NC \type {\it} \NC \it \fontid\font \NC \NR
+\NC bold italic \NC \type {\bi} \NC \bi \fontid\font \NC \NR
+\LL
 \stoptabulate
 
 These numbers depend on the macro package used because each one has its own way
@@ -620,12 +817,15 @@ 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.
 
-\subsection{\type {\setfontid}}
+The primitive \lpr {setfontid} can be used to enable a font with the given id,
+which of course needs to be a valid one.
 
-The primitive \type {\setfontid} can be used to enable a font with the given id
-(which of course needs to be a valid one).
+\stopsubsection
 
-\subsection{\type {\noligs} and \type {\nokerns}}
+\startsubsection[title={\lpr {noligs} and \lpr {nokerns}}]
+
+\topicindex {ligatures+suppress}
+\topicindex {kerns+suppress}
 
 These primitives prohibit ligature and kerning insertion at the time when the
 initial node list is built by \LUATEX's main control loop. You can enable these
@@ -642,15 +842,19 @@ kerning functions, i.e.\ by assigning dummy functions to their associated
 callbacks. Keep in mind that when you define a font (using \LUA) you can also
 omit the kern and ligature tables, which has the same effect as the above.
 
-\subsection{\type{\nospaces}}
+\stopsubsection
+
+\startsubsection[title={\type{\nospaces}}]
+
+\topicindex {spaces+suppress}
 
-This new primitive can be used to overrule the usual \type {\spaceskip}
-related heuristics when a space character is seen in a text flow. The
-value~\type{1} triggers no injection while \type{2} results in injection of
-a zero skip. Below we see the results for four characters separated by a
+This new primitive can be used to overrule the usual \prm {spaceskip} related
+heuristics when a space character is seen in a text flow. The value~\type{1}
+triggers no injection while \type{2} results in injection of a zero skip. In \in
+{figure} [fig:nospaces] we see the results for four characters separated by a
 space.
 
-\startlinecorrection
+\startplacefigure[reference=fig:nospaces,title={The \lpr {nospaces} options.}]
 \startcombination[3*2]
     {\ruledhbox to 5cm{\vtop{\hsize 10mm\nospaces=0\relax x x x x \par}\hss}} {\type {0 / hsize 10mm}}
     {\ruledhbox to 5cm{\vtop{\hsize 10mm\nospaces=1\relax x x x x \par}\hss}} {\type {1 / hsize 10mm}}
@@ -659,24 +863,30 @@ space.
     {\ruledhbox to 5cm{\vtop{\hsize  1mm\nospaces=1\relax x x x x \par}\hss}} {\type {1 / hsize 1mm}}
     {\ruledhbox to 5cm{\vtop{\hsize  1mm\nospaces=2\relax x x x x \par}\hss}} {\type {2 / hsize 1mm}}
 \stopcombination
-\stoplinecorrection
+\stopplacefigure
+
+\stopsubsection
+
+\stopsection
+
+\startsection[title={Tokens, commands and strings}]
 
-\section{Tokens, commands and strings}
+\startsubsection[title={\lpr {scantextokens}}]
 
-\subsection{\type {\scantextokens}}
+\topicindex {tokens+scanning}
 
-The syntax of \type {\scantextokens} is identical to \type {\scantokens}. This
-primitive is a slightly adapted version of \ETEX's \type {\scantokens}. The
+The syntax of \lpr {scantextokens} is identical to \prm {scantokens}. This
+primitive is a slightly adapted version of \ETEX's \prm {scantokens}. The
 differences are:
 
 \startitemize
 \startitem
-    The last (and usually only) line does not have a \type {\endlinechar}
+    The last (and usually only) line does not have a \prm {endlinechar}
     appended.
 \stopitem
 \startitem
-    \type {\scantextokens} never raises an EOF error, and it does not execute
-    \type {\everyeof} tokens.
+    \lpr {scantextokens} never raises an EOF error, and it does not execute
+    \prm {everyeof} tokens.
 \stopitem
 \startitem
     There are no \quote {\unknown\ while end of file \unknown} error tests
@@ -685,7 +895,10 @@ differences are:
 \stopitem
 \stopitemize
 
-\subsection{\type {\toksapp}, \type {\tokspre}, \type {\etoksapp} and \type {\etokspre}}
+\stopsubsection
+
+\startsubsection[title={\lpr {toksapp}, \lpr {tokspre}, \lpr {etoksapp}, \lpr {etokspre},
+\lpr {gtoksapp}, \lpr {gtokspre}, \lpr {xtoksapp},  \lpr {xtokspre}}]
 
 Instead of:
 
@@ -700,15 +913,17 @@ you can use:
 \stoptyping
 
 The \type {pre} variants prepend instead of append, and the \type {e} variants
-expand the passed general text.
+expand the passed general text. The \type {g} and \type {x} variants are global.
+
+\stopsubsection
 
-\subsection{\type {\csstring}, \type {\begincsname} and \type {\lastnamedcs}}
+\startsubsection[title={\prm {csstring}, \lpr {begincsname} and \lpr {lastnamedcs}}]
 
-These are somewhat special. The \type {\csstring} primitive is like
-\type {\string} but it omits the leading escape character. This can be
-somewhat more efficient that stripping it of afterwards.
+These are somewhat special. The \prm {csstring} primitive is like
+\prm {string} but it omits the leading escape character. This can be
+somewhat more efficient than stripping it afterwards.
 
-The \type {\begincsname} primitive is like \type {\csname} but doesn't create
+The \lpr {begincsname} primitive is like \prm {csname} but doesn't create
 a relaxed equivalent when there is no such name. It is equivalent to
 
 \starttyping
@@ -718,10 +933,8 @@ a relaxed equivalent when there is no such name. It is equivalent to
 \stoptyping
 
 The advantage is that it saves a lookup (don't expect much speedup) but more
-important is that it avoids using the \type {\if}.
-
-The \type {\lastnamedcs} is one that should be used with care. The above
-example could be written as:
+important is that it avoids using the \prm {if} test. The \lpr {lastnamedcs}
+is one that should be used with care. The above example could be written as:
 
 \starttyping
 \ifcsname foo\endcsname
@@ -731,9 +944,13 @@ example could be written as:
 
 This is slightly more efficient than constructing the string twice (deep down in
 \LUATEX\ this also involves some \UTF8 juggling), but probably more relevant is
-that it saves a few tokens and can make code a bit more more readable.
+that it saves a few tokens and can make code a bit more readable.
+
+\stopsubsection
 
-\subsection{\type {\clearmarks}}
+\startsubsection[title={\lpr {clearmarks}}]
+
+\topicindex {marks}
 
 This primitive complements the \ETEX\ mark primitives and clears a mark class
 completely, resetting all three connected mark texts to empty. It is an
@@ -743,71 +960,241 @@ immediate command.
 \clearmarks <16-bit number>
 \stopsyntax
 
-\subsection{\type{\letcharcode}}
+\stopsubsection
+
+\startsubsection[title={\lpr {alignmark} and \lpr {aligntab}}]
+
+The primitive \lpr {alignmark} duplicates the functionality of \type {#} inside
+alignment preambles, while \lpr {aligntab} duplicates the functionality of \type
+{&}.
 
-This primitive is still experimental but can be used to assign a meaning to an active
-character, as in:
+\stopsubsection
+
+\startsubsection[title={\lpr {letcharcode}}]
+
+This primitive can be used to assign a meaning to an active character, as in:
 
 \starttyping
 \def\foo{bar} \letcharcode123=\foo
 \stoptyping
 
-This can be a bit nicer that using the uppercase tricks (using the property of
-\type {\uppercase} that it treats active characters special).
+This can be a bit nicer than using the uppercase tricks (using the property of
+\prm {uppercase} that it treats active characters special).
 
-\section{Boxes, rules and leaders}
+\stopsubsection
 
-\subsection{\type {\outputbox}}
+\startsubsection[title={\lpr {glet}}]
 
-\startsyntax
-\outputbox = 65535
-\stopsyntax
+This primitive is similar to:
+
+\starttyping
+\protected\def\glet{\global\let}
+\stoptyping
+
+but faster (only measurable with millions of calls) and probably more convenient
+(after all we also have \type {\gdef}).
+
+\stopsubsection
+
+\startsubsection[title={\lpr {expanded}, \lpr {immediateassignment} and \lpr {immediateassigned}}]
+
+\topicindex {expansion}
+
+The \lpr {expanded} primitive takes a token list and expands it content which can
+come in handy: it avoids a tricky mix of \prm {expandafter} and \prm {noexpand}.
+You can compare it with what happens inside the body of an \prm {edef}. But this
+kind of expansion it still doesn't expand some primitive operations.
+
+\startbuffer
+\newcount\NumberOfCalls
+
+\def\TestMe{\advance\NumberOfCalls1 }
+
+\edef\Tested{\TestMe foo:\the\NumberOfCalls}
+\edef\Tested{\TestMe foo:\the\NumberOfCalls}
+\edef\Tested{\TestMe foo:\the\NumberOfCalls}
+
+\meaning\Tested
+\stopbuffer
+
+\typebuffer
+
+The result is a macro that has the not expanded code in its body:
+
+\getbuffer
+
+Instead we can define \tex {TestMe} in a way that expands the assignment
+immediately. You need of course to be aware of preventing look ahead interference
+by using a space or \tex {relax} (often an expression works better as it doesn't
+leave an \tex {relax}).
+
+\startbuffer
+\def\TestMe{\immediateassignment\advance\NumberOfCalls1 }
+
+\edef\Tested{\TestMe foo:\the\NumberOfCalls}
+\edef\Tested{\TestMe foo:\the\NumberOfCalls}
+\edef\Tested{\TestMe foo:\the\NumberOfCalls}
+
+\meaning\Tested
+\stopbuffer
+
+\typebuffer
+
+This time the counter gets updates and we don't see interference in the
+resulting \tex {Tested} macro:
+
+\getbuffer
+
+Here is a somewhat silly example of expanded comparison:
+
+\startbuffer
+\def\expandeddoifelse#1#2#3#4%
+  {\immediateassignment\edef\tempa{#1}%
+   \immediateassignment\edef\tempb{#2}%
+   \ifx\tempa\tempb
+     \immediateassignment\def\next{#3}%
+   \else
+     \immediateassignment\def\next{#4}%
+   \fi
+   \next}
+
+\edef\Tested
+  {(\expandeddoifelse{abc}{def}{yes}{nop}/%
+    \expandeddoifelse{abc}{abc}{yes}{nop})}
+
+\meaning\Tested
+\stopbuffer
+
+\typebuffer
+
+It gives:
+
+\getbuffer
+
+A variant is:
+
+\starttyping
+\def\expandeddoifelse#1#2#3#4%
+  {\immediateassigned{
+     \edef\tempa{#1}%
+     \edef\tempb{#2}%
+   }%
+   \ifx\tempa\tempb
+     \immediateassignment\def\next{#3}%
+   \else
+     \immediateassignment\def\next{#4}%
+   \fi
+   \next}
+\stoptyping
+
+The possible error messages are the same as using assignments in preambles of
+alignments and after the \prm {accent} command. The supported assignments are the
+so called prefixed commands (except box assignments).
+
+\stopsubsection
+
+\startsubsection[title={\lpr {ifcondition}}]
+
+\topicindex {conditions}
+
+This is a somewhat special one. When you write macros conditions need to be
+properly balanced in order to let \TEX's fast branch skipping work well. This new
+primitive is basically a no||op flagged as a condition so that the scanner can
+recognize it as an if|-|test. However, when a real test takes place the work is
+done by what follows, in the next example \tex {something}.
+
+\starttyping
+\unexpanded\def\something#1#2%
+  {\edef\tempa{#1}%
+   \edef\tempb{#2}
+   \ifx\tempa\tempb}
+
+\ifcondition\something{a}{b}%
+    \ifcondition\something{a}{a}%
+        true 1
+    \else
+        false 1
+    \fi
+\else
+    \ifcondition\something{a}{a}%
+        true 2
+    \else
+        false 2
+    \fi
+\fi
+\stoptyping
+
+If you are familiar with \METAPOST, this is a bit like \type {vardef} where the macro
+has a return value. Here the return value is a test.
+
+\stopsubsection
 
-This new integer parameter allows you to alter the number of the box that will be
+\stopsection
+
+\startsection[title={Boxes, rules and leaders}]
+
+\startsubsection[title={\lpr {outputbox}}]
+
+\topicindex {output}
+
+This 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.
 
-\subsection{\type {\vpack}, \type {\hpack} and \type {\tpack}}
+\startsyntax
+\outputbox = 12345
+\stopsyntax
+
+\stopsubsection
 
-These three primitives are like \type {\vbox}, \type {\hbox} and \type {\vtop}
+\startsubsection[title={\prm {vpack}, \prm {hpack} and \prm {tpack}}]
+
+These three primitives are like \prm {vbox}, \prm {hbox} and \prm {vtop}
 but don't apply the related callbacks.
 
-\subsection{\type {\vsplit}}
+\stopsubsection
+
+\startsubsection[title={\prm {vsplit}}]
+
+\topicindex {splitting}
 
-The \type {\vsplit} primitive has to be followed by a specification of the
-required height. As alternative for the \type {to} keyword you can use \type
-{upto} to get a split of the given size but result has the natural dimensions
-then.
+The \prm {vsplit} primitive has to be followed by a specification of the required
+height. As alternative for the \type {to} keyword you can use \type {upto} to get
+a split of the given size but result has the natural dimensions then.
 
-\subsection{Images and Forms}
+\stopsubsection
+
+\startsubsection[title={Images and reused box objects},reference=sec:imagedandforms]
 
 These two concepts are now core concepts and no longer whatsits. They are in fact
 now implemented as rules with special properties. Normal rules have subtype~0,
 saved boxes have subtype~1 and images have subtype~2. This has the positive side
-effect that whenever we need to take content with dimensions into account, when we
-look at rule nodes, we automatically also deal with these two types.
+effect that whenever we need to take content with dimensions into account, when
+we look at rule nodes, we automatically also deal with these two types.
 
 The syntax of the \type {\save...resource} is the same as in \PDFTEX\ but you
 should consider them to be backend specific. This means that a macro package
 should treat them as such and check for the current output mode if applicable.
-Here are the equivalents:
 
-\starttabulate[|l|l|]
-\NC \type {\saveboxresource}             \EQ \type {\pdfxform}           \NC \NR
-\NC \type {\saveimageresource}           \EQ \type {\pdfximage}          \NC \NR
-\NC \type {\useboxresource}              \EQ \type {\pdfrefxform}        \NC \NR
-\NC \type {\useimageresource}            \EQ \type {\pdfrefximage}       \NC \NR
-\NC \type {\lastsavedboxresourceindex}   \EQ \type {\pdflastxform}       \NC \NR
-\NC \type {\lastsavedimageresourceindex} \EQ \type {\pdflastximage}      \NC \NR
-\NC \type {\lastsavedimageresourcepages} \EQ \type {\pdflastximagepages} \NC \NR
+\starttabulate[|l|p|]
+\DB command \BC explanation \NC \NR
+\TB
+\NC \lpr {saveboxresource}             \NC save the box as an object to be included later \NC \NR
+\NC \lpr {saveimageresource}           \NC save the image as an object to be included later \NC \NR
+\NC \lpr {useboxresource}              \NC include the saved box object here (by index) \NC \NR
+\NC \lpr {useimageresource}            \NC include the saved image object here (by index) \NC \NR
+\NC \lpr {lastsavedboxresourceindex}   \NC the index of the last saved box object \NC \NR
+\NC \lpr {lastsavedimageresourceindex} \NC the index of the last saved image object \NC \NR
+\NC \lpr {lastsavedimageresourcepages} \NC the number of pages in the last saved image object \NC \NR
+\LL
 \stoptabulate
 
 \LUATEX\ accepts optional dimension parameters for \type {\use...resource} in the
 same format as for rules. With images, these dimensions are then used instead of
-the ones given to \type {\useimageresource} but the original dimensions are not
-overwritten, so that a \type {\useimageresource} without dimensions still
-provides the image with dimensions defined by \type {\saveimageresource}. These
-optional parameters are not implemented for \type {\saveboxresource}.
+the ones given to \lpr {useimageresource} but the original dimensions are not
+overwritten, so that a \lpr {useimageresource} without dimensions still
+provides the image with dimensions defined by \lpr {saveimageresource}. These
+optional parameters are not implemented for \lpr {saveboxresource}.
 
 \starttyping
 \useimageresource width 20mm height 10mm depth 5mm \lastsavedimageresourceindex
@@ -820,35 +1207,51 @@ is the \type {type} key. When set to non|-|zero the \type {/Type} entry is
 omitted. A value of 1 or 3 still writes a \type {/BBox}, while 2 or 3 will write
 a \type {/Matrix}.
 
-\subsection{\type {\nohrule} and \type {\novrule}}
+\stopsubsection
+
+\startsubsection[title={\lpr {nohrule} and \lpr {novrule}}]
+
+\topicindex {rules}
 
 Because introducing a new keyword can cause incompatibilities, two new primitives
-were introduced: \type {\nohrule} and \type {\novrule}. These can be used to
+were introduced: \lpr {nohrule} and \lpr {novrule}. These can be used to
 reserve space. This is often more efficient than creating an empty box with fake
-dimensions).
+dimensions.
+
+\stopsubsection
 
-\subsection{\type {\gleaders}}
+\startsubsection[title={\lpr {gleaders}}]
+
+\topicindex {leaders}
 
 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
+they are like normal \prm {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 {Languages}
+\stopsubsection
+
+\stopsection
 
-\subsection{\type {\hyphenationmin}}
+\startsection[title={Languages}]
+
+\startsubsection[title={\lpr {hyphenationmin}}]
+
+\topicindex {languages}
+\topicindex {hyphenation}
 
 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}
+within the constraints of the \prm {lefthyphenmin} and \prm {righthyphenmin}
 values (as stored in the glyph node). This primitive accepts a number and stores
 the value with the language.
 
-\subsection{\type {\boundary}, \type {\noboundary}, \type {\protrusionboundary} and \type
-{\wordboundary}}
+\stopsubsection
+
+\startsubsection[title={\prm {boundary}, \prm {noboundary}, \prm {protrusionboundary} and \prm {wordboundary}}]
 
-The \type {\noboundary} commands used to inject a whatsit node but now injects a normal
-node with type \type {boundary} and subtype~0. In addition you can say:
+The \prm {noboundary} command is used to inject a whatsit node but now injects a normal
+node with type \nod {boundary} and subtype~0. In addition you can say:
 
 \starttyping
 x\boundary 123\relax y
@@ -858,31 +1261,57 @@ This has the same effect but the subtype is now~1 and the value~123 is stored.
 The traditional ligature builder still sees this as a cancel boundary directive
 but at the \LUA\ end you can implement different behaviour. The added benefit of
 passing this value is a side effect of the generalization. The subtypes~2 and~3
-are used to control protrusion and word boundaries in hyphenation.
+are used to control protrusion and word boundaries in hyphenation and have
+related primitives.
 
-\section{Control and debugging}
+\stopsubsection
 
-\subsection {Tracing}
+\stopsection
 
-If \type {\tracingonline} is larger than~2, the node list display will also print
+\startsection[title={Control and debugging}]
+
+\startsubsection[title={Tracing}]
+
+\topicindex {tracing}
+
+If \prm {tracingonline} is larger than~2, the node list display will also print
 the node number of the nodes.
 
-\subsection{\type {\outputmode} and \type {\draftmode}}
+\stopsubsection
 
-The \type {\outputmode} variable tells \LUATEX\ what it has to produce:
+\startsubsection[title={\lpr {outputmode}}]
+
+\topicindex {output}
+\topicindex {backend}
+
+The \lpr {outputmode} variable tells \LUATEX\ what it has to produce:
 
 \starttabulate[|l|l|]
+\DB value \BC output \NC \NR
+\TB
 \NC \type {0} \NC \DVI\ code \NC \NR
 \NC \type {1} \NC \PDF\ code \NC \NR
+\LL
 \stoptabulate
 
-The value of the \type {\draftmode} counter signals the backend if it should
-output less. The \PDF\ backend accepts a value of~$1$, while the \DVI\ backend
-ignores the value.
+\stopsubsection
+
+\startsubsection[title={\lpr {draftmode}}]
 
-\section {Files}
+The value of the \lpr {draftmode} counter signals the backend if it should output
+less. The \PDF\ backend accepts a value of~1, while the \DVI\ backend ignores the
+value. This is no critical feature so we can remove it in future versions when it
+can make the backend cleaner.
 
-\subsection{File syntax}
+\stopsubsection
+
+\stopsection
+
+\startsection[title={Files}]
+
+\startsubsection[title={File syntax}]
+
+\topicindex {files+names}
 
 \LUATEX\ will accept a braced argument as a file name:
 
@@ -894,26 +1323,49 @@ ignores the value.
 This allows for embedded spaces, without the need for double quotes. Macro
 expansion takes place inside the argument.
 
-The \type {\tracingfonts} primitive that has been inherited from \PDFTEX\ has
+The \lpr {tracingfonts} primitive that has been inherited from \PDFTEX\ has
 been adapted to support variants in reporting the font. The reason for this
 extension is that a csname not always makes sense. The zero case is the default.
 
-\starttabulate[|T||]
-\NC 0 \EQ \type{\foo xyz} \NC \NR
-\NC 1 \EQ \type{\foo (bar)} \NC \NR
-\NC 2 \EQ \type{<bar> xyz} \NC \NR
-\NC 3 \EQ \type{<bar @ ..pt> xyz} \NC \NR
-\NC 4 \EQ \type{<id>} \NC \NR
-\NC 5 \EQ \type{<id: bar>} \NC \NR
-\NC 6 \EQ \type{<id: bar @ ..pt> xyz} \NC \NR
+\starttabulate[|l|l|]
+\DB value \BC reported \NC \NR
+\TB
+\NC \type{0} \NC \type{\foo xyz} \NC \NR
+\NC \type{1} \NC \type{\foo (bar)} \NC \NR
+\NC \type{2} \NC \type{<bar> xyz} \NC \NR
+\NC \type{3} \NC \type{<bar @ ..pt> xyz} \NC \NR
+\NC \type{4} \NC \type{<id>} \NC \NR
+\NC \type{5} \NC \type{<id: bar>} \NC \NR
+\NC \type{6} \NC \type{<id: bar @ ..pt> xyz} \NC \NR
+\LL
 \stoptabulate
 
-\subsection{Writing to file}
+\stopsubsection
+
+\startsubsection[title={Writing to file}]
+
+\topicindex {files+writing}
 
-You can now open upto 127 files with \type {\openout}. When no file is open
+You can now open upto 127 files with \prm {openout}. When no file is open
 writes will go to the console and log. As a consequence a system command is
 no longer possible but one can use \type {os.execute} to do the same.
 
+\stopsubsection
+
+\stopsection
+
+\startsection[title={Math}]
+
+\topicindex {math}
+
+We will cover math extensions in its own chapter because not only the font
+subsystem and spacing model have been enhanced (thereby introducing many new
+primitives) but also because some more control has been added to existing
+functionality. Much of this relates to the different approaches of traditional
+\TEX\ fonts and \OPENTYPE\ math.
+
+\stopsection
+
 \stopchapter
 
 \stopcomponent
-- 
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