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-% language=uk
-
-\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 the decision was made to clean
-up the rather hybrid nature of the program. This means that some primitives 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. In \in
-{chapter} [enhancements] we discussed some new primitives, here we will cover
-most of the adapted ones.
-
-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. As a consequence instead of one large file plus change files, we
-    now have multiple files organized in categories like \type {tex}, \type
-    {pdf}, \type {lang}, \type {font}, \type {lua}, etc. There are some artefacts
-    of the conversion to \CCODE, but in due time we will clean up the source code
-    and make sure that the documentation is done right. Many files are in the
-    \CWEB\ format, but others, like those interfacing to \LUA, are \CCODE\ files.
-    Of course we want to stay as close as possible to the original so that the
-    documentation of the fundamentals behind \TEX\ by Don Knuth still applies.
-\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
-    Magnification (\type {\mag}) is only supported in \DVI\ output mode. You can
-    set this parameter and it even works with \type {true} units till you switch
-    to \PDF\ output mode. When you use \PDF\ output you can best not touch the
-    \type {\mag} variable. This fuzzy behaviour is not much different from using
-    \PDF\ backend related functionality while eventually \DVI\ output is
-    required.
-
-    After the output mode has been frozen (normally that happens when the first
-    page is shipped out) or when \PDF\ output is enabled, the \type {true}
-    specification is ignored. When you preload a plain format adapted to
-    \LUATEX\ it can be that the \type {\mag} parameter already has been set.
-\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 adaptations.
-
-\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. Instead we use the \OMEGA\ approach to directionality.
-\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
-    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.
-
-For compatibility reasons we still refer to \type {\pdf...} commands but \LUATEX\
-has a different backend interface. Instead of these primitives there are three
-interfacing primitives: \type {\pdfextension}, \type {\pdfvariable} and
-\type {\pdffeedback} that take keywords and optional further arguments. This way
-we can extend the features when needed but don't need to adapt the core engine.
-The front- and backend are decoupled as much as possible.
-
-\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
-    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. Because \LUATEX\ has a different subsystem for managing images,
-    more diversion from its ancestor happened in the meantime.
-\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 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
-
-\startitem
-    When \type {\adjustspacing} has value~2, hz optimization will be applied to
-    glyphs and kerns. When the value is~3, only glyphs will be treated. A value
-    smaller than~2 disables this feature.
-\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 {\pdfcopyfont} primitive is now \type {\copyfont}.
-\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
-    The introspective primitives \type {\pdflastximagecolordepth} and \type
-    {\pdfximagebbox} have been removed. One can use external applications to
-    determine these properties or use the built|-|in \type {img} library.
-\stopitem
-
-\startitem
-    The initializers \type {\pdfoutput} has been replaced by \type {\outputmode} and
-    \type {\pdfdraftmode} is now \type {\draftmode}.
-\stopitem
-
-\startitem
-    The pixel multiplier dimension \type {\pdfpxdimen} lots its prefix and is now calles
-    \type {\pxdimen}.
-\stopitem
-
-\startitem
-    An extra \type {\pdfimageaddfilename} option has been added that can be used to block
-    writing the filename to the \PDF\ file.
-\stopitem
-
-\startitem
-    The primitive \type {\pdftracingfonts} is now \type {\tracingfonts} as it
-    doesn't relate to the backend.
-\stopitem
-
-\startitem
-    The experimental primitive \type {\pdfinsertht} is kept as \type {\insertht}.
-\stopitem
-
-\startitem
-    The promotion of primitives to core primitives as well as the separation of
-    font- and backend means that the initialization namespace \type {pdftex} is
-    gone.
-\stopitem
-
-\stopitemize
-
-One change involves the so called xforms and ximages. In \PDFTEX\ these are
-implemented as so called whatsits. But contrary to other whatsits they have
-dimensions that need to be taken into account when for instance calculating
-optimal line breaks. In \LUATEX\ these are now promoted to normal nodes, which
-simplifies code that needs those dimensions.
-
-Another reason for promotion is that these are useful concepts. Backends can
-provide the ability to use content that has been rendered in several places,
-and images are also common. For that reason we also changed the names:
-
-\starttabulate[|l|l|]
-\NC \bf new name                         \NC \bf old name \NC \NR
-\NC \type {\saveboxresource}             \NC \type {\pdfxform}           \NC \NR
-\NC \type {\saveimageresource}           \NC \type {\pdfximage}          \NC \NR
-\NC \type {\useboxresource}              \NC \type {\pdfrefxform}        \NC \NR
-\NC \type {\useimageresource}            \NC \type {\pdfrefximage}       \NC \NR
-\NC \type {\lastsavedboxresourceindex}   \NC \type {\pdflastxform}       \NC \NR
-\NC \type {\lastsavedimageresourceindex} \NC \type {\pdflastximage}      \NC \NR
-\NC \type {\lastsavedimageresourcepages} \NC \type {\pdflastximagepages} \NC \NR
-\stoptabulate
-
-There are a few \type {\pdffeedback} features that relate to this but these are
-typical backend specific ones. The index that gets returned is to be considered
-as \quote {just a number} and although it still has the same meaning (object
-related) as before, you should not depend on that.
-
-The protrusion detection mechanism is enhanced a bit to enable a bit more complex
-situations. When protrusion characters are identified some nodes are skipped:
-
-\startitemize[packed]
-\startitem zero glue \stopitem
-\startitem penalties \stopitem
-\startitem empty discretionaries \stopitem
-\startitem normal zero kerns \stopitem
-\startitem rules with zero dimensions \stopitem
-\startitem math nodes with a surround of zero \stopitem
-\startitem dir nodes \stopitem
-\startitem empty horizontal lists \stopitem
-\startitem local par nodes \stopitem
-\startitem inserts, marks and adjusts \stopitem
-\startitem boundaries \stopitem
-\startitem whatsits \stopitem
-\stopitemize
-
-Because this can not be enough, you can also use a protrusion boundary node to
-make the next node being ignored. When the value is~1 or~3, the next node will be
-ignored in the test when locating a left boundary condition. When the value is~2
-or~3, the previous node will be ignored when locating a right boundary condition
-(the search goes from right to left). This permits protrusion combined with for
-instance content moved into the margin:
-
-\starttyping
-\protrusionboundary1\llap{!\quad}«Who needs protrusion?»
-\stoptyping
-
-\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 has been removed completely and 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 have been fixed an confusing implementation details have been sorted
-    out.
-\stopitem
-
-\startitem
-    The scanner for direction specifications now allows an optional space after
-    the direction is completely parsed.
-\stopitem
-
-\startitem
-    The \type {^^} notation has been extended: after \type {^^^^} four hexadecimal
-    characters are expected and after \type {^^^^^^} six hexadecimal characters
-    have to be given. The original \TEX\ interpretation is still valid for the
-    \type {^^} case but the four and six variants do no backtracking, i.e.\ when
-    they are not followed by the right number of hexadecimal digits they issue an
-    error message. Because \type{^^^} is a normal \TEX\ case, we don't support the
-    odd number of \type {^^^^^} either.
-\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. The \type {\hoffset} and
-    \type {\voffset} primitives have been fixed.
-\stopitem
-
-\startitem
-    The primitives \type {\charwd}, \type {\charht}, \type {\chardp} and \type
-    {\charit} have been removed 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 means that the initialization namespace \type {aleph} is gone.
-\stopitem
-
-\stopitemize
-
-The above let's itself summarize as: we took the 32 bit aspects and much of the
-directional mechanisms.
-
-\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 encoding related command line 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 \WEBC\ 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[reference=backendprimitives,title=The backend primitives \type {\pdf*}]
-
-In a previous section we mentioned that some \PDFTEX\ primitives were removed and
-others promoted to core \LUATEX\ primitives. That is only part of the story. In
-order to separate the backend specific primitives in de code these commands are
-now replaced by only a few. In traditional \TEX\ we only had the \DVI\ backend
-but now we have two: \DVI\ and \PDF. Additional functionality is implemented as
-\quote {extensions} in \TEX speak. By separating more strickly we are able to
-keep the core (fontend) clean and stable. If for some reason an extra backend
-option is needed, it can be implemented without touching the core. The three
-\PDF\ backend related primitives are
-
-\starttyping
-\pdfextension command [specification]
-\pdfvariable  name
-\pdffeedback  name
-\stoptyping
-
-An extension triggers further parsing, depending on the command given. A variable is
-a (kind of) register and can be read and written, while a feedback is reporting
-something (as it comes from the backend it's normally a sequence of tokens).
-
-In order for \LUATEX\ to be more than just \TEX\ you need to enable primitives. That
-has already be the case right from the start. If you want the traditional \PDFTEX\
-primitives (for as far their functionality is still around) you now can do this:
-
-\starttyping
-\protected\def\pdfliteral             {\pdfextension literal}
-\protected\def\pdfcolorstack          {\pdfextension colorstack}
-\protected\def\pdfsetmatrix           {\pdfextension setmatrix}
-\protected\def\pdfsave                {\pdfextension save\relax}
-\protected\def\pdfrestore             {\pdfextension restore\relax}
-\protected\def\pdfobj                 {\pdfextension obj }
-\protected\def\pdfrefobj              {\pdfextension refobj }
-\protected\def\pdfannot               {\pdfextension annot }
-\protected\def\pdfstartlink           {\pdfextension startlink }
-\protected\def\pdfendlink             {\pdfextension endlink\relax}
-\protected\def\pdfoutline             {\pdfextension outline }
-\protected\def\pdfdest                {\pdfextension dest }
-\protected\def\pdfthread              {\pdfextension thread }
-\protected\def\pdfstartthread         {\pdfextension startthread }
-\protected\def\pdfendthread           {\pdfextension endthread\relax}
-\protected\def\pdfinfo                {\pdfextension info }
-\protected\def\pdfcatalog             {\pdfextension catalog }
-\protected\def\pdfnames               {\pdfextension names }
-\protected\def\pdfincludechars        {\pdfextension includechars }
-\protected\def\pdffontattr            {\pdfextension fontattr }
-\protected\def\pdfmapfile             {\pdfextension mapfile }
-\protected\def\pdfmapline             {\pdfextension mapline }
-\protected\def\pdftrailer             {\pdfextension trailer }
-\protected\def\pdfglyphtounicode      {\pdfextension glyphtounicode }
-\stoptyping
-
-The introspective primitives can be defined as:
-
-\starttyping
-\def\pdftexversion    {\numexpr\pdffeedback version\relax}
-\def\pdftexrevision           {\pdffeedback revision}
-\def\pdflastlink      {\numexpr\pdffeedback lastlink\relax}
-\def\pdfretval        {\numexpr\pdffeedback retval\relax}
-\def\pdflastobj       {\numexpr\pdffeedback lastobj\relax}
-\def\pdflastannot     {\numexpr\pdffeedback lastannot\relax}
-\def\pdfxformname     {\numexpr\pdffeedback xformname\relax}
-\def\pdfcreationdate          {\pdffeedback creationdate}
-\def\pdffontname      {\numexpr\pdffeedback fontname\relax}
-\def\pdffontobjnum    {\numexpr\pdffeedback fontobjnum\relax}
-\def\pdffontsize      {\dimexpr\pdffeedback fontsize\relax}
-\def\pdfpageref       {\numexpr\pdffeedback pageref\relax}
-\def\pdfcolorstackinit        {\pdffeedback colorstackinit}
-\stoptyping
-
-The configuration related registers have become:
-
-\starttyping
-\edef\pdfcompresslevel            {\pdfvariable compresslevel}
-\edef\pdfobjcompresslevel         {\pdfvariable objcompresslevel}
-\edef\pdfdecimaldigits            {\pdfvariable decimaldigits}
-\edef\pdfgamma                    {\pdfvariable gamma}
-\edef\pdfimageresolution          {\pdfvariable imageresolution}
-\edef\pdfimageapplygamma          {\pdfvariable imageapplygamma}
-\edef\pdfimagegamma               {\pdfvariable imagegamma}
-\edef\pdfimagehicolor             {\pdfvariable imagehicolor}
-\edef\pdfimageaddfilename         {\pdfvariable imageaddfilename}
-\edef\pdfpkresolution             {\pdfvariable pkresolution}
-\edef\pdfpkfixeddpi               {\pdfvariable pkfixeddpi}
-\edef\pdfinclusioncopyfonts       {\pdfvariable inclusioncopyfonts}
-\edef\pdfinclusionerrorlevel      {\pdfvariable inclusionerrorlevel}
-\edef\pdfignoreunknownimages      {\pdfvariable ignoreunknownimages}
-\edef\pdfgentounicode             {\pdfvariable gentounicode}
-\edef\pdfpagebox                  {\pdfvariable pagebox}
-\edef\pdfminorversion             {\pdfvariable minorversion}
-\edef\pdfuniqueresname            {\pdfvariable uniqueresname}
-
-\edef\pdfhorigin                  {\pdfvariable horigin}
-\edef\pdfvorigin                  {\pdfvariable vorigin}
-\edef\pdflinkmargin               {\pdfvariable linkmargin}
-\edef\pdfdestmargin               {\pdfvariable destmargin}
-\edef\pdfthreadmargin             {\pdfvariable threadmargin}
-\edef\pdfxformmargin              {\pdfvariable xformmargin}
-
-\edef\pdfpagesattr                {\pdfvariable pagesattr}
-\edef\pdfpageattr                 {\pdfvariable pageattr}
-\edef\pdfpageresources            {\pdfvariable pageresources}
-\edef\pdfxformattr                {\pdfvariable xformattr}
-\edef\pdfxformresources           {\pdfvariable xformresources}
-\edef\pdfpkmode                   {\pdfvariable pkmode}
-
-\edef\pdfsuppressoptionalinfo     {\pdfvariable suppressoptionalinfo }
-\edef\pdftrailerid                {\pdfvariable trailerid }
-\stoptyping
-
-The variables are internal ones, so they are anonymous. When you ask for the
-meaning of a few previously defined ones:
-
-\starttyping
-\meaning\pdfhorigin
-\meaning\pdfcompresslevel
-\meaning\pdfpageattr
-\stoptyping
-
-you will get:
-
-\starttyping
-macro:->[internal backend dimension]
-macro:->[internal backend integer]
-macro:->[internal backend tokenlist]
-\stoptyping
-
-The \type {\edef} can also be an \type {\def} but it's a bit more efficient
-to expand the lookup related register beforehand. After that you can adapt
-the defaults; these are:
-
-\starttyping
-\pdfcompresslevel         9
-\pdfobjcompresslevel      1 % used: (0,9)
-\pdfdecimaldigits         4 % used: (3,6)
-\pdfgamma              1000
-\pdfimageresolution      71
-\pdfimageapplygamma       0
-\pdfimagegamma         2200
-\pdfimagehicolor          1
-\pdfimageaddfilename      1
-\pdfpkresolution         72
-\pdfpkfixeddpi            0
-\pdfinclusioncopyfonts    0
-\pdfinclusionerrorlevel   0
-\pdfignoreunknownimages   0
-\pdfgentounicode          0
-\pdfpagebox               0
-\pdfminorversion          4
-\pdfuniqueresname         0
-
-\pdfhorigin             1in
-\pdfvorigin             1in
-\pdflinkmargin          0pt
-\pdfdestmargin          0pt
-\pdfthreadmargin        0pt
-\pdfxformmargin         0pt
-\stoptyping
-
-If you also want some backward compatibility, you can add:
-
-\starttyping
-\let\pdfpagewidth      \pagewidth
-\let\pdfpageheight     \pageheight
-
-\let\pdfadjustspacing  \adjustspacing
-\let\pdfprotrudechars  \protrudechars
-\let\pdfnoligatures    \ignoreligaturesinfont
-\let\pdffontexpand     \expandglyphsinfont
-\let\pdfcopyfont       \copyfont
-
-\let\pdfxform          \saveboxresource
-\let\pdflastxform      \lastsavedboxresourceindex
-\let\pdfrefxform       \useboxresource
-
-\let\pdfximage         \saveimageresource
-\let\pdflastximage     \lastsavedimageresourceindex
-\let\pdflastximagepages\lastsavedimageresourcepages
-\let\pdfrefximage      \useimageresource
-
-\let\pdfsavepos        \savepos
-\let\pdflastxpos       \lastxpos
-\let\pdflastypos       \lastypos
-
-\let\pdfoutput         \outputmode
-\let\pdfdraftmode      \draftmode
-
-\let\pdfpxdimen        \pxdimen
-
-\let\pdfinsertht       \insertht
-
-\let\pdfnormaldeviate  \normaldeviate
-\let\pdfuniformdeviate \uniformdeviate
-\let\pdfsetrandomseed  \setrandomseed
-\let\pdfrandomseed     \randomseed
-
-\let\pdfprimitive      \primitive
-\let\ifpdfprimitive    \ifprimitive
-
-\let\ifpdfabsnum       \ifabsnum
-\let\ifpdfabsdim       \ifabsdim
-\stoptyping
-
-And even:
-
-\starttyping
-\newdimen\pdfeachlineheight
-\newdimen\pdfeachlinedepth
-\newdimen\pdflastlinedepth
-\newdimen\pdffirstlineheight
-\newdimen\pdfignoreddimen
-\stoptyping
-
-The backend is derived from \PDFTEX\ so the same syntax applies. However, the
-\type {outline} command accepts a \type {objnum} followed by a number. No
-checking takes place so when this is used it had better be a valid (flushed)
-object.
-
-In order to be (more or less) compatible with \PDFTEX\ we also support the
-option to suppress some info:
-
-\starttyping
-\pdfvariable suppressoptionalinfo \numexpr
-        0
-    +   1   % PTEX.FullBanner
-    +   2   % PTEX.FileName
-    +   4   % PTEX.PageNumber
-    +   8   % PTEX.InfoDict
-    +  16   % Creator
-    +  32   % CreationDate
-    +  64   % ModDate
-    + 128   % Producer
-    + 256   % Trapped
-    + 512   % ID
-\relax
-\stoptyping
-
-In addition you can overload the trailer id, but we don't do any checking on
-validity, so you have to pass a valid array. The following is like the ones
-normally generated by the engine:
-
-\starttyping
-\pdfvariable trailerid {[
-    <FA052949448907805BA83C1E78896398>
-    <FA052949448907805BA83C1E78896398>
-]}
-\stoptyping
-
-So, you even need to include the brackets!
-
-Although we started from a merge of \PDFTEX\ and \ALEPH, by now the code base as
-well as functionality has diverted from those parents. Here we show the options
-that can be passed to the extensions.
-
-\starttexsyntax
-\pdfextension literal
-    [ direct | page ] { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension dest
-    num integer | name { tokens }!crlf
-    [ fitbh | fitbv | fitb | fith| fitv | fit |
-      fitr <rule spec> | xyz [ zoom <integer> ]
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension annot
-    reserveobjnum | useobjnum <integer>
-    { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension save
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension restore
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension setmatrix
-    { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-[ \immediate ] \pdfextension obj
-    reserveobjnum
-\stoptexsyntax
-
-\starttexsyntax
-[ \immediate ] \pdfextension obj
-    [ useobjnum <integer> ]
-    [ uncompressed ]
-    [ stream  [ attr { tokens } ] ]
-    [ file ]
-    { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension refobj
-    <integer>
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension colorstack
-    <integer>
-    set { tokens } | push { tokens } | pop | current
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension startlink
-    [ attr { tokens } ]
-    user { tokens } | goto | thread
-    [ file { tokens } ]
-    [ page <integer> { tokens } | name { tokens } | num  integer ]
-    [ newwindow  | nonewwindow ]
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension endlink
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension startthread
-    num <integer> | name { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension endthread
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension thread
-    num <integer> | name { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension outline
-    [ attr { tokens } ]
-    [ useobjnum <integer> ]
-    [ count <integer> ]
-    { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension glyphtounicode
-    { tokens }
-    { tokens }
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension catalog
-    { tokens }
-    [ openaction
-      user { tokens } | goto | thread
-      [ file { tokens } ]
-      [ page <integer> { tokens } | name { tokens } | num <integer> ]
-      [ newwindow  | nonewwindow ] ]
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension fontattr
-    <integer>
-    {tokens}
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension mapfile
-    {tokens}
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension mapline
-    {tokens}
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension includechars
-    {tokens}
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension info
-    {tokens}
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension names
-    {tokens}
-\stoptexsyntax
-
-\starttexsyntax
-\pdfextension trailer
-    {tokens}
-\stoptexsyntax
-
-\stopsection
-
-\startsection[title=Directions]
-
-The directional model in \LUATEX\ is inherited from \OMEGA|/|\ALEPH\ but we tried
-to improve it a bit. At some point we played with recovery of modes but that was
-disabled later on when we found that it interfered with nested directions. That
-itself had as side effect that the node list was no longer balanced with respect
-to directional nodes which in turn can give side effects when a series of dir
-changes happens without grouping.
-
-The current (0.97 onward) approach is that we again make the list balanced but
-try to avoid some side effects. What happens is quite intuitive if we forget
-about spaces (turned into glue) but even there what happens makes sense if you
-look at it in detail. However that logic makes in|-|group switching kind of
-useless when no proper nested grouping is used: switching from right to left
-several times nested, results in spacing ending up after each other due to nested
-mirroring. Of course a sane macro package will manage this for the user but here
-we are discussing the low level dir injection.
-
-This is what happens:
-
-\starttyping
-\textdir TRT nur {\textdir TLT run \textdir TRT NUR} nur
-\stoptyping
-
-This becomes stepwise:
-
-\startnarrower
-\starttyping
-injected: [+TRT]nur {[+TLT]run [+TRT]NUR} nur
-balanced: [+TRT]nur {[+TLT]run [-TLT][+TRT]NUR[-TRT]} nur[-TRT]
-result  : run {RUNrun } run
-\stoptyping
-\stopnarrower
-
-And this:
-
-\starttyping
-\textdir TRT nur {nur \textdir TLT run \textdir TRT NUR} nur
-\stoptyping
-
-becomes:
-
-\startnarrower
-\starttyping
-injected: [+TRT]nur {nur [+TLT]run [+TRT]NUR} nur
-balanced: [+TRT]nur {nur [+TLT]run [-TLT][+TRT]NUR[-TRT]} nur[-TRT]
-result  : run {run RUNrun } run
-\stoptyping
-\stopnarrower
-
-Now, in the following examples watch where we put the braces:
-
-\startbuffer
-\textdir TRT nur {{\textdir TLT run} {\textdir TRT NUR}} nur
-\stopbuffer
-
-\typebuffer
-
-This becomes:
-
-\startnarrower
-\getbuffer
-\stopnarrower
-
-Compare this to:
-
-\startbuffer
-\textdir TRT nur {{\textdir TLT run }{\textdir TRT NUR}} nur
-\stopbuffer
-
-\typebuffer
-
-Which renders as:
-
-\startnarrower
-\getbuffer
-\stopnarrower
-
-So how do we deal with the next?
-
-\startbuffer
-\def\ltr{\textdir TLT\relax}
-\def\rtl{\textdir TRT\relax}
-
-run {\rtl nur {\ltr run \rtl NUR \ltr run \rtl NUR} nur}
-run {\ltr run {\rtl nur \ltr RUN \rtl nur \ltr RUN} run}
-\stopbuffer
-
-\typebuffer
-
-It gets typeset as:
-
-\startnarrower
-\startlines
-\getbuffer
-\stoplines
-\stopnarrower
-
-We could define the two helpers to look back, pick up a skip, remove it and
-inject it after the dir node. But that way we loose the subtype information that
-for some applications can be handy to be kept as|-|is. This is why we now have a
-variant of \type {\textdir} which injects the balanced node before the skip.
-Instead of the previous definition we can use:
-
-\startbuffer[def]
-\def\ltr{\linedir TLT\relax}
-\def\rtl{\linedir TRT\relax}
-\stopbuffer
-
-\typebuffer[def]
-
-and this time:
-
-\startbuffer[txt]
-run {\rtl nur {\ltr run \rtl NUR \ltr run \rtl NUR} nur}
-run {\ltr run {\rtl nur \ltr RUN \rtl nur \ltr RUN} run}
-\stopbuffer
-
-\typebuffer[txt]
-
-comes out as a properly spaced:
-
-\startnarrower
-\startlines
-\getbuffer[def,txt]
-\stoplines
-\stopnarrower
-
-Anything more complex that this, like combination of skips and penalties, or
-kerns, should be handled in the input or macro package because there is no way we
-can predict the expected behaviour. In fact, the \type {\linedir} is just a
-convenience extra which could also have been implemented using node list parsing.
-
-Another adaptation to the \ALEPH\ directional model is control over shapes driven
-by \type {\hangindent} and \type {\parshape}. This is controlled by a new parameter
-\type {\shapemode}:
-
-\starttabulate[|cTB|c|]
-\NC   \NC \bf \type {\hangindent} \NC \bf \type {\parshape} \NC \NR
-\NC 0 \NC  normal                 \NC normal                \NC \NR
-\NC 1 \NC  mirrored               \NC normal                \NC \NR
-\NC 2 \NC  normal                 \NC mirrored              \NC \NR
-\NC 3 \NC  mirrored               \NC mirrored              \NC \NR
-\stoptabulate
-
-The value is reset to zero (like \type {\hangindent} and \type {\parshape})
-after the paragraph is done with. You can use negative values to preven t
-this.
-
-In \in {figure} [fig:shapemode] a few examples are given.
-
-\startplacefigure[reference=fig:shapemode,title={The effect of \type {shapemode}.}]
-    \startcombination[2*3]
-        {\ruledvbox \bgroup \setuptolerance[verytolerant]
-            \hsize .45\textwidth \switchtobodyfont[6pt]
-                \pardir TLT \textdir TLT
-                \hangindent 40pt \hangafter -3
-                \leftskip10pt \input tufte \par
-         \egroup} {TLT: hangindent}
-        {\ruledvbox \bgroup \setuptolerance[verytolerant]
-            \hsize .45\textwidth \switchtobodyfont[6pt]
-            \pardir TLT \textdir TLT
-            \parshape 4 0pt .8\hsize 10pt .8\hsize 20pt .8\hsize 0pt \hsize
-            \input tufte \par
-         \egroup} {TLT: parshape}
-        {\ruledvbox \bgroup \setuptolerance[verytolerant]
-            \hsize .45\textwidth \switchtobodyfont[6pt]
-            \pardir TRT \textdir TRT
-            \hangindent 40pt \hangafter -3
-            \leftskip10pt \input tufte \par
-         \egroup} {TRT: hangindent mode 0}
-        {\ruledvbox \bgroup \setuptolerance[verytolerant]
-            \hsize .45\textwidth \switchtobodyfont[6pt]
-            \pardir TRT \textdir TRT
-            \parshape 4 0pt .8\hsize 10pt .8\hsize 20pt .8\hsize 0pt \hsize
-            \input tufte \par
-         \egroup} {TRT: parshape mode 0}
-        {\ruledvbox \bgroup \setuptolerance[verytolerant]
-            \hsize .45\textwidth \switchtobodyfont[6pt]
-            \shapemode=3
-            \pardir TRT \textdir TRT
-            \hangindent 40pt \hangafter -3
-            \leftskip10pt \input tufte \par
-         \egroup} {TRT: hangindent mode 1 & 3}
-        {\ruledvbox \bgroup \setuptolerance[verytolerant]
-            \hsize .45\textwidth \switchtobodyfont[6pt]
-            \shapemode=3
-            \pardir TRT \textdir TRT
-            \parshape 4 0pt .8\hsize 10pt .8\hsize 20pt .8\hsize 0pt \hsize
-            \input tufte \par
-         \egroup} {TRT: parshape mode 2 & 3}
-    \stopcombination
-\stopplacefigure
-
-\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}. We mention this because using the \TEX book as
-reference is still quite valid but not for memory related details. Another
-significate detail is that we have double linked node lists and that some nodes
-carry more data.
-
-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. Details like this are
-of no concern to users.
-
-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} (and the new \type {\hjcode}) 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}, \type {\uccode} and \type
-{\hjcode} assignments do not yet show up when using the \ETEX\ tracing routines
-\type {\tracingassigns} and \type {\tracingrestores}.
-
-A side|-|effect of the current implementation is that \type {\global} is now more
-expensive in terms of processing than non|-|global assignments.
-
-The glyph ids within a font are also managed by means of a sparse array as 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 \type {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 \CCODE\ 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 \IO\ subsystem).
-
-\stopsubsection
-
-\stopsection
-
-\stopchapter
-
-\stopcomponent