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+%D \module
+%D   [       file=syst-ini,
+%D        version=2008.11.04, % 2001.11.16, % 1999.03.17,  % an oldie: 1995.10.10
+%D          title=\CONTEXT\ System Macros,
+%D       subtitle=Bootstrapping \TEX,
+%D         author=Hans Hagen,
+%D           date=\currentdate,
+%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
+%C
+%C This module is part of the \CONTEXT\ macro||package and is
+%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
+%C details.
+
+%D We used to load plain \TEX\ in a special way, but redefining a couple of
+%D primitives so that for instance font loading was ignored. For those interested,
+%D this loader is found in \type {syst-tex.tex}. Some of the comment's are Don
+%D Knuths and more of it can be found in the plain \TEX\ format.
+%D
+%D Characters can have special states, that can be triggered by setting their
+%D category coded. Some are preset, others are to be set as soon as possible,
+%D otherwise we cannot define any useful macros.
+%D
+%D First we define a bunch of constants. Normally we would \type {\setconstant}
+%D but we're prestine and have no macros defined yet. Abstraction also makes it
+%D possible to avoid the \type {^^} in the input.
+
+\chardef\escapecatcode             0
+\chardef\begingroupcatcode         1
+\chardef\endgroupcatcode           2
+\chardef\mathshiftcatcode          3
+\chardef\alignmentcatcode          4
+\chardef\endoflinecatcode          5
+\chardef\parametercatcode          6
+\chardef\superscriptcatcode        7
+\chardef\subscriptcatcode          8
+\chardef\ignorecatcode             9
+\chardef\spacecatcode             10
+\chardef\lettercatcode            11
+\chardef\othercatcode             12  % finally obsolete: \let\other \othercatcode
+\chardef\activecatcode            13  % finally obsolete: \let\active\activecatcode
+\chardef\commentcatcode           14
+\chardef\invalidcatcode           15
+
+%chardef\zeroasciicode             0
+\chardef\tabasciicode              9
+\chardef\newlineasciicode         10  % don't confuse this one with \endoflineasciicode
+\chardef\formfeedasciicode        12
+\chardef\endoflineasciicode       13  % somewhat messy but this can be the active \par
+\chardef\endoffileasciicode       26
+\chardef\spaceasciicode           32
+\chardef\exclamationmarkasciicode 33 % ! used in namespace protection
+\chardef\doublequoteasciicode     34 % "
+\chardef\hashasciicode            35
+\chardef\dollarasciicode          36
+\chardef\commentasciicode         37
+\chardef\ampersandasciicode       38
+\chardef\singlequoteasciicode     39 % '
+\chardef\primeasciicode           39 % '
+\chardef\leftparentasciicode      40
+\chardef\rightparentasciicode     41
+\chardef\hyphenasciicode          45
+\chardef\forwardslashasciicode    47 % /
+\chardef\colonasciicode           58
+\chardef\lessthanasciicode        60 % < used as alternative verbatim {
+\chardef\morethanasciicode        62 % > used as alternative verbatim }
+\chardef\questionmarkasciicode    63 % ? used in namespace protection
+\chardef\atsignasciicode          64 % @ used in namespace protection
+\chardef\backslashasciicode       92 % `\\
+\chardef\circumflexasciicode      94
+\chardef\underscoreasciicode      95
+\chardef\leftbraceasciicode      123 % `\{
+\chardef\barasciicode            124 % `\|
+\chardef\rightbraceasciicode     125 % `\}
+\chardef\tildeasciicode          126 % `\~
+\chardef\delasciicode            127
+
+%catcode\zeroasciicode           \ignorecatcode      % `\^^@   ascii null is ignored
+\catcode\tabasciicode            \spacecatcode       % `\^^I   ascii tab is a blank space
+\catcode\formfeedasciicode       \activecatcode      % `\^^L   ascii form-feed (active, set later)
+%catcode\endoflineasciicode      \endoflinecatcode   % `\^^M   ascii return is end-line
+\catcode\endoffileasciicode      \ignorecatcode      % `\^^Z   endoffile (ignored in ConTeXt)
+%catcode\spaceasciicode          \spacecatcode       % `\      ascii space is blank space
+\catcode\hashasciicode           \parametercatcode   % `\#     hash mark is macro parameter character
+\catcode\dollarasciicode         \mathshiftcatcode   % `\$     dollar sign is math shift
+%catcode\commentasciicode        \commentcatcode     % `\%     percent sign is comment character
+\catcode\ampersandasciicode      \alignmentcatcode   % `\&     ampersand is alignment tab
+%catcode\backslashasciicode      \escapecatcode      % `\\     backslash is TeX escape character
+\catcode\circumflexasciicode     \superscriptcatcode % `\^     circumflex and uparrow are for superscripts
+\catcode\underscoreasciicode     \subscriptcatcode   % `\_     underline and downarrow are for subscripts
+\catcode\leftbraceasciicode      \begingroupcatcode  % `\{     left brace is begin-group character
+\catcode\rightbraceasciicode     \endgroupcatcode    % `\}     right brace is end-group character
+\catcode\tildeasciicode          \activecatcode      % `\~     tilde is active
+%catcode\delasciicode            \invalidcatcode     % `\^^?   ascii delete is invalid
+
+\chardef\statuswrite   128
+
+%D Initialization of primitives.
+
+\directlua {
+    local baseprimitives = tex.extraprimitives("core","tex")
+    local moreprimitives = tex.extraprimitives("etex","luatex")
+
+    tex.enableprimitives("",moreprimitives)
+
+    tex.enableprimitives("normal",baseprimitives)
+    tex.enableprimitives("normal",moreprimitives)
+
+    function tex.enableprimitives() end
+}
+
+\def\space{ }
+\def\empty{}
+
+\letcharcode \formfeedasciicode \par    % \def ^^L{\par}  formfeed
+\letcharcode \tildeasciicode    \       %                 tilde
+\letcharcode \spaceasciicode    \space  %                 space
+
+\expandafter\def\csname\Uchar\tabasciicode      \endcsname {\ }   % \def\^^I{\ }    tab
+\expandafter\def\csname\Uchar\formfeedasciicode \endcsname {\par} % \def\^^L{\par}  formfeed
+\expandafter\def\csname\Uchar\endoflineasciicode\endcsname {\ }   % \def\^^M{\ }    return
+
+%D For now:
+
+\def\gobbleoneargument#1{} % will be defined later on anyway
+
+%D First we define a simplified version of the \CONTEXT\ protection mechanism.
+%D Later we will implement a better variant.
+
+\def\unprotect
+  {\edef\protect
+     {\catcode\atsignasciicode         \the\catcode\atsignasciicode         \relax
+      \catcode\exclamationmarkasciicode\the\catcode\exclamationmarkasciicode\relax
+      \catcode\questionmarkasciicode   \the\catcode\questionmarkasciicode   \relax
+      \catcode\underscoreasciicode     \the\catcode\underscoreasciicode     \relax
+      \let\protect\relax}%
+   \catcode\atsignasciicode         \lettercatcode
+   \catcode\exclamationmarkasciicode\lettercatcode
+   \catcode\questionmarkasciicode   \lettercatcode
+   \catcode\underscoreasciicode     \lettercatcode}
+
+\let\protect\relax
+
+\unprotect
+
+%D Some pretty important definitions:
+
+\let\bgroup={
+\let\egroup=}
+
+%D \macros
+%D   {normalbgroup,normalgroup}
+%D
+%D No comment.
+
+%D Allocation of registers is done slightly different than in plain \TEX. First of
+%D all we use different reserved counters. We also don't implement a family handler
+%D because users are not supposed to implement their own math. We reserve the lowest
+%D 31 registers for scratch purposes. Keep in mind that in the core engine some
+%D registers are reserved: counters 0 upto 9, and counter 255.
+%D
+%D As with plain \TEX\ we recommend that macro designers always use \type {\global}
+%D assignments with respect to registers numbered 1, 3, 5 \unknown\ 31, and always
+%D non||\type {\global} assignments with respect to registers 0, 2, 4, \unknown\ 30.
+%D This will prevent \quote {save stack buildup} that might otherwise occur.
+%D
+%D We reserve some registers for special (management) purposes:
+
+%   0 -  20 : scratch
+%  21 - 127 : internal
+% 128 - 254 : inserts
+% 255       : page
+% 256 -     : user
+
+\countdef   \c_syst_min_allocated_register   =    52 \c_syst_min_allocated_register   =   256 % can change
+\countdef   \c_syst_max_allocated_register   =    53 \c_syst_max_allocated_register   = 32767
+\countdef   \c_syst_min_allocated_read       =    54 \c_syst_min_allocated_read       =    -1
+\countdef   \c_syst_max_allocated_read       =    55 \c_syst_max_allocated_read       =    16
+\countdef   \c_syst_min_allocated_language   =    56 \c_syst_min_allocated_language   =     0
+\countdef   \c_syst_max_allocated_language   =    57 \c_syst_max_allocated_language   =   255
+\countdef   \c_syst_min_allocated_insert     =    58 \c_syst_min_allocated_insert     =   128
+\countdef   \c_syst_max_allocated_insert     =    59 \c_syst_max_allocated_insert     =   254
+\countdef   \c_syst_min_allocated_family     =    60 \c_syst_min_allocated_family     =   128
+\countdef   \c_syst_max_allocated_family     =    61 \c_syst_max_allocated_family     =   255
+\countdef   \c_syst_min_allocated_attribute  =    62 \c_syst_min_allocated_attribute  =  1024 % 0-1023 : private
+\countdef   \c_syst_min_allocated_write      =    63 \c_syst_min_allocated_write      =     0
+\countdef   \c_syst_max_allocated_write      =    64 \c_syst_max_allocated_write      =   127
+
+\countdef   \c_syst_last_allocated_count     =    32 \c_syst_last_allocated_count     = \c_syst_min_allocated_register
+\countdef   \c_syst_last_allocated_dimen     =    33 \c_syst_last_allocated_dimen     = \c_syst_min_allocated_register
+\countdef   \c_syst_last_allocated_skip      =    34 \c_syst_last_allocated_skip      = \c_syst_min_allocated_register
+\countdef   \c_syst_last_allocated_muskip    =    35 \c_syst_last_allocated_muskip    = \c_syst_min_allocated_register
+\countdef   \c_syst_last_allocated_box       =    36 \c_syst_last_allocated_box       = \c_syst_min_allocated_register
+\countdef   \c_syst_last_allocated_toks      =    37 \c_syst_last_allocated_toks      = \c_syst_min_allocated_register
+\countdef   \c_syst_last_allocated_read      =    38 \c_syst_last_allocated_read      = \c_syst_min_allocated_read
+\countdef   \c_syst_last_allocated_write     =    39 \c_syst_last_allocated_write     = \c_syst_min_allocated_write
+\countdef   \c_syst_last_allocated_marks     =    40 \c_syst_last_allocated_marks     = \c_syst_min_allocated_register
+\countdef   \c_syst_last_allocated_language  =    41 \c_syst_last_allocated_language  = \c_syst_min_allocated_language    % not used in context
+\countdef   \c_syst_last_allocated_insertion =    42 \c_syst_last_allocated_insertion = \c_syst_min_allocated_insert
+\countdef   \c_syst_last_allocated_family    =    43 \c_syst_last_allocated_family    = \c_syst_min_allocated_family      % not used in context
+\countdef   \c_syst_last_allocated_attribute =    44 \c_syst_last_allocated_attribute = \c_syst_min_allocated_attribute   % not used in context
+
+\countdef   \c_syst_min_counter_value =   125 \c_syst_min_counter_value = -"7FFFFFFF % beware, we use index 125 at the lua end
+\countdef   \c_syst_max_counter_value =   126 \c_syst_max_counter_value =  "7FFFFFFF % beware, we use index 126 at the lua end
+
+\countdef   \zerocount                =   120 \zerocount                =  0
+\countdef   \plusone                  =   121 \plusone                  =  1
+\countdef   \minusone                 =   122 \minusone                 = -1
+
+\countdef   \normalpagebox            =   127 \normalpagebox            = 255  % hardcoded in pdftex/xetex
+
+% Only to be used by developers in very special cases!
+
+% \def\lastallocatedcount    {\the\c_syst_last_allocated_count}
+% \def\lastallocateddimen    {\the\c_syst_last_allocated_dimen}
+% \def\lastallocatedskip     {\the\c_syst_last_allocated_skip}
+% \def\lastallocatedmuskip   {\the\c_syst_last_allocated_muskip}
+% \def\lastallocatedbox      {\the\c_syst_last_allocated_dimen}
+% \def\lastallocatedtoks     {\the\c_syst_last_allocated_toks}
+% \def\lastallocatedattribute{\the\c_syst_last_allocated_attribute}
+
+% A few traditional allocations (these might go):
+
+\countdef \count@   255 % hm, used in \newif .. todo: replace it there
+\dimendef \dimen@     0
+\dimendef \dimen@i    1 % global only
+\dimendef \dimen@ii   2
+
+%D So, effectively we start allocating from 256 and upwards. The inserts sit in the
+%D range 128 upto 254. Page numbers use the counters 0 upto 9 and the pagebox is
+%D 255. Users can use the scratch registers upto 31 without problem but all others
+%D are reserved.
+
+\let\wlog\gobbleoneargument % Let's get rid of this one.
+
+%D The allocators share a common helper macro.
+
+\normalprotected\def\newcount   {\syst_basics_allocate\c_syst_last_allocated_count    \count   \countdef   \c_syst_max_allocated_register}
+\normalprotected\def\newdimen   {\syst_basics_allocate\c_syst_last_allocated_dimen    \dimen   \dimendef   \c_syst_max_allocated_register}
+\normalprotected\def\newskip    {\syst_basics_allocate\c_syst_last_allocated_skip     \skip    \skipdef    \c_syst_max_allocated_register}
+\normalprotected\def\newmuskip  {\syst_basics_allocate\c_syst_last_allocated_muskip   \muskip  \muskipdef  \c_syst_max_allocated_register}
+\normalprotected\def\newbox     {\syst_basics_allocate\c_syst_last_allocated_box      \box     \mathchardef\c_syst_max_allocated_register}
+\normalprotected\def\newtoks    {\syst_basics_allocate\c_syst_last_allocated_toks     \toks    \toksdef    \c_syst_max_allocated_register}
+\normalprotected\def\newread    {\syst_basics_allocate\c_syst_last_allocated_read     \read    \chardef    \c_syst_max_allocated_read}
+\normalprotected\def\newwrite   {\syst_basics_allocate\c_syst_last_allocated_write    \write   \chardef    \c_syst_max_allocated_write}
+\normalprotected\def\newmarks   {\syst_basics_allocate\c_syst_last_allocated_marks    \marks   \mathchardef\c_syst_max_allocated_register}
+\normalprotected\def\newinsert  {\syst_basics_allocate\c_syst_last_allocated_insertion\insert  \chardef    \c_syst_max_allocated_insert}
+
+%D We don't need these in \CONTEXT:
+
+\normalprotected\def\newlanguage{\syst_basics_allocate\c_syst_last_allocated_language \language\chardef    \c_syst_max_allocated_language}
+\normalprotected\def\newfamily  {\syst_basics_allocate\c_syst_last_allocated_family   \fam     \chardef    \c_syst_max_allocated_family}
+
+\let\newfam\newfamily
+
+\firstvalidlanguage\plusone
+
+% Watch out, for the moment we disable the check for already being defined
+% later we will revert this but first all chardefs must be replaced.
+
+\normalprotected\def\newconstant       #1{\ifdefined#1\let#1\undefined\fi\newcount#1}
+\normalprotected\def\setnewconstant    #1{\ifdefined#1\let#1\undefined\fi\newcount#1#1} % just a number
+\normalprotected\def\setconstant         {}                                             % dummy, no checking, so it warns
+\normalprotected\def\setconstantvalue#1#2{\csname#1\endcsname\numexpr#2\relax}
+
+% maybe setconstant with check
+
+% %D The next definitions are really needed (in \CONTEXT):
+
+\newlinechar\newlineasciicode  \edef\outputnewlinechar{\Uchar\newlineasciicode} % {^^J}
+
+%D One reason to start high with allocation is that it permits us to allocate
+%D consecutive ranges more easily, for instance if for \MPLIB\ we want to allocate a
+%D continuous range of boxes. It also permits us to do a proper upward allocation
+%D for inserts. The current code evolved from code that dealt with older engines but
+%D as all engines now provide many registers we removed all traces.
+
+\ifdefined\writestatus \else
+   %\normalprotected\def\writestatus#1#2{\immediate\write\statuswrite{#1: #2}}
+    \normalprotected\def\writestatus#1#2{\message{#1: #2}}
+\fi
+
+\def\syst_basics_allocate_yes#1#2#3#4#5% last class method max name
+  {\ifnum#1<#4\relax
+     \global\advance#1\plusone
+     \global#3#5=#1\relax
+   \else
+     \writestatus{warning}{no room for \string#2\space \string#5\space (max: \number#4)}%
+   \fi}
+
+\def\syst_basics_allocate_nop#1#2#3#4#5% last class method max name
+  {\writestatus{warning}{\string#2 \string#5 is already defined (\string\relax\space it first)}}
+
+\def\syst_basics_allocate#1#2#3#4#5% last class method max name
+  {\ifx#5\undefined
+     \expandafter\syst_basics_allocate_yes
+   \else\ifx#5\relax
+     \expandafter\expandafter\expandafter\syst_basics_allocate_yes
+   \else
+     \expandafter\expandafter\expandafter\syst_basics_allocate_nop
+   \fi\fi
+   #1#2#3#4#5}
+
+%D Since the number of chars exceed 256 now, we can use \type {\chardef} instead of
+%D the more limited \type {\mathchardef}.
+
+\normalprotected\def\newbox  {\syst_basics_allocate\c_syst_last_allocated_box  \box  \chardef\c_syst_max_allocated_register}
+\normalprotected\def\newmarks{\syst_basics_allocate\c_syst_last_allocated_marks\marks\chardef\c_syst_max_allocated_register}
+
+%D Attributes are something very \LUATEX. In \CONTEXT\ you are not supposed to use
+%D the attributes directly but always allocate then first. For instance attribute~0
+%D is reserved for special purposes (this might change). Attributes in the range
+%D 128-1023 are private and should not be touched.
+
+\let\attributeunsetvalue\c_syst_min_counter_value % used to be \minusone
+
+\normalprotected\def\newattribute{\syst_basics_allocate\c_syst_last_allocated_attribute\attribute\attributedef\c_syst_max_allocated_register}
+
+%D Not used by \CONTEXT\ but for instance \PICTEX\ needs it. It's a trick to force
+%D strings instead of tokens that take more memory. It's a trick to trick to force
+%D strings. This macro is never used in \CONTEXT.
+
+%normalprotected\def\newhelp#1#2{\newtoks#1#1\expandafter{\csname#2\endcsname}}
+\normalprotected\def\newhelp#1#2{\newtoks#1#1\expandafter{\detokenize{#2}}}
+
+%D \macros
+%D   {scratchcounter,
+%D    scratchdimen,scratchskip,scratchmuskip,
+%D    scratchbox,
+%D    scratchtoks}
+%D
+%D We now define a few scratch registers, so that successive loads at least have
+%D some available. The private ones are used in cases where we don't want to
+%D intrude on normal scratch ones.
+
+\newcount \scratchcounter  \newcount \globalscratchcounter  \newcount \privatescratchcounter
+\newdimen \scratchdimen    \newdimen \globalscratchdimen    \newdimen \privatescratchdimen
+\newskip  \scratchskip     \newskip  \globalscratchskip     \newskip  \privatescratchskip
+\newmuskip\scratchmuskip   \newmuskip\globalscratchmuskip   \newmuskip\privatescratchmuskip
+\newtoks  \scratchtoks     \newtoks  \globalscratchtoks     \newtoks  \privatescratchtoks
+\newbox   \scratchbox      \newbox   \globalscratchbox      \newbox   \privatescratchbox
+
+\newcount\scratchcounterone  \newcount\scratchcountertwo  \newcount\scratchcounterthree
+\newdimen  \scratchdimenone  \newdimen  \scratchdimentwo  \newdimen  \scratchdimenthree
+\newskip    \scratchskipone  \newskip    \scratchskiptwo  \newskip    \scratchskipthree
+\newmuskip\scratchmuskipone  \newmuskip\scratchmuskiptwo  \newmuskip\scratchmuskipthree
+\newtoks    \scratchtoksone  \newtoks    \scratchtokstwo  \newtoks    \scratchtoksthree
+\newbox      \scratchboxone  \newbox      \scratchboxtwo  \newbox      \scratchboxthree
+
+\newcount\scratchcounterfour \newcount\scratchcounterfive \newcount\scratchcountersix
+\newdimen  \scratchdimenfour \newdimen  \scratchdimenfive \newdimen  \scratchdimensix
+\newskip    \scratchskipfour \newskip    \scratchskipfive \newskip    \scratchskipsix
+\newmuskip\scratchmuskipfour \newmuskip\scratchmuskipfive \newmuskip\scratchmuskipsix
+\newtoks    \scratchtoksfour \newtoks    \scratchtoksfive \newtoks    \scratchtokssix
+\newbox      \scratchboxfour \newbox      \scratchboxfive \newbox      \scratchboxsix
+
+\newcount\globalscratchcounterone
+\newcount\globalscratchcountertwo
+\newcount\globalscratchcounterthree
+
+%D \macros
+%D   {tempstring}
+
+\let\tempstring\empty
+
+%D \macros
+%D   {scratchwidth, scratchheight, scratchdepth, scratchoffset, scratchdistance}
+%D
+%D A few more scratch dimensions:
+
+\newdimen\scratchwidth
+\newdimen\scratchheight
+\newdimen\scratchdepth
+
+\newdimen\scratchoffset
+\newdimen\scratchleftoffset
+\newdimen\scratchrightoffset
+\newdimen\scratchtopoffset
+\newdimen\scratchbottomoffset
+
+\newdimen\scratchdistance
+
+\newdimen\scratchhsize
+\newdimen\scratchvsize
+
+\newdimen\scratchxoffset
+\newdimen\scratchyoffset
+\newdimen\scratchhoffset
+\newdimen\scratchvoffset
+
+\newdimen\scratchxposition
+\newdimen\scratchyposition
+
+\newcount\scratchnx
+\newcount\scratchny
+
+\newcount\scratchmx
+\newcount\scratchmy
+
+\newcount\scratchmin
+\newcount\scratchmax
+
+\newcount\scratchunicode
+
+\newdimen\scratchleftskip
+\newdimen\scratchrightskip
+\newdimen\scratchtopskip
+\newdimen\scratchbottomskip
+
+%D More allocations:
+
+\newskip  \zeroskip      \zeroskip      0pt plus 0pt minus 0pt
+\newdimen \zeropoint     \zeropoint     0pt
+\newdimen \onepoint      \onepoint      1pt
+\newdimen \halfapoint    \halfapoint    0.5pt
+\newdimen \maxdimen      \maxdimen      16383.99999pt % 1073741823sp
+\newcount \maxcount      \maxcount      2147483647
+\newdimen \onebasepoint  \onebasepoint  1bp
+\newdimen \scaledpoint   \scaledpoint   1sp
+\newdimen \thousandpoint \thousandpoint 1000pt
+\newmuskip\zeromuskip    \zeromuskip    0mu
+\newmuskip\onemuskip     \onemuskip     1mu
+
+\newmuskip\muquad        \muquad        18mu
+
+\let\points   \onepoint
+\let\halfpoint\halfapoint
+
+\newtoks \emptytoks
+
+%D And even more: (todo: countdefs 60+)
+
+%newcount\minusone \minusone    -1
+\newcount\minustwo \minustwo    -2
+%chardef \zerocount              0
+%chardef \plusone                1
+\chardef \plustwo                2
+\chardef \plusthree              3
+\chardef \plusfour               4
+\chardef \plusfive               5
+\chardef \plussix                6
+\chardef \plusseven              7
+\chardef \pluseight              8
+\chardef \plusnine               9
+\chardef \plusten               10
+\chardef \plussixteen           16
+\chardef \plusfifty             50
+\chardef \plushundred          100
+\chardef \plusonehundred       100
+\chardef \plustwohundred       200
+\chardef \plusfivehundred      500
+\chardef \pluscxxvii           127
+\chardef \pluscxxviii          128
+\chardef \pluscclv             255
+\chardef \pluscclvi            256
+\chardef \plusthousand        1000
+\chardef \plustenthousand    10000
+\chardef \plustwentythousand 20000
+\chardef \medcard            32768
+\chardef \maxcard            65536 % pdftex has less mathchars
+\chardef \maxcardminusone    65535
+
+%D \macros
+%D   {doubleexpandafter,tripleexpandafter,expanded,startexpanded}
+%D
+%D A few handy shortcuts
+
+\let\singleexpandafter \expandafter
+\def\doubleexpandafter{\expandafter\expandafter\expandafter}
+\def\tripleexpandafter{\expandafter\doubleexpandafter\expandafter}
+
+%D We prefer the more readable variant than in plain \TEX. User should only
+%D use \type {\emptybox}:
+
+\newbox\voidbox  % public
+
+\let\normalhbox\hbox
+\let\normalvbox\vbox
+
+\def\unvoidbox{\unhbox\voidbox}
+\def\emptybox {\box   \voidbox}  % used in initializations so no attributes
+\def\emptyvbox{\normalvpack{}}   % no copy as we need to set attributes
+\def\emptyhbox{\normalhpack{}}   % no copy as we need to set attributes
+
+\let\leavevmode\unvoidbox % we prefer to use \dontleavehmode
+
+%D \macros
+%D   {dontcomplain}
+%D
+%D We need this one soon:
+
+\normalprotected\def\dontcomplain
+  {\hbadness\plustenthousand
+   \vbadness\plustenthousand
+   \hfuzz   \maxdimen
+   \vfuzz   \maxdimen}
+
+%D Some expected plain variants follow. We don't reuse registers because we
+%D don't want clashes.
+
+\let     \p@             \onepoint
+\let     \m@ne           \minusone
+\let     \z@             \zeropoint
+\let     \@ne            \plusone
+\let     \tw@            \plustwo
+\let     \thr@@          \plusthree
+\let     \sixt@@n        \plussixteen
+\let     \@cclv          \pluscclv
+\let     \@cclvi         \pluscclvi
+\let     \voidb@x        \voidbox
+\newtoks \toks@        % \scratchtoks
+
+%D We define \type {\newif} a la plain \TEX, but will redefine it later. As
+%D Knuth says:
+%D
+%D \startnarrower
+%D And here's a different sort of allocation: for example,
+%D
+%D \starttyping
+%D \newif\iffoo
+%D \stoptyping
+%D
+%D creates \type {\footrue}, \type {\foofalse} to go with \type {\iffoo}.
+%D \stopnarrower
+
+% \normalprotected\def\newif#1%
+%   {\count@\escapechar
+%    \escapechar\minusone
+%    \expandafter\expandafter\expandafter\def\new_if #1{true}{\let#1\iftrue }%
+%    \expandafter\expandafter\expandafter\def\new_if#1{false}{\let#1\iffalse}%
+%    \new_if#1{false}% the condition starts out false
+%    \escapechar\count@}
+%
+% \def\new_if#1#2%
+%   {\csname\expandafter\if@\string#1#2\endcsname}
+%
+% \bgroup % `if' is required
+%   \uccode`1=`i \uccode`2=`f \uppercase{\gdef\if@12{}}
+% \egroup
+
+% We use \csstring so there is no need to push/pop escapechar.
+% We use different names so that we get a better error message.
+%
+% \normalprotected\def\newif#1%
+%   {\let\new_if_saved\newif
+%    \let\newif\new_if_check
+%    \expandafter\expandafter\expandafter\def\new_if_cs #1{true}{\let#1\iftrue }%
+%    \expandafter\expandafter\expandafter\def\new_if_cs#1{false}{\let#1\iffalse}%
+%    \new_if_cs#1{false}%
+%    \let\newif\new_if_saved}
+%
+% \normalprotected\def\new_if_cs#1#2%
+%   {\csname\expandafter\newif\csstring#1#2\endcsname}
+%
+% We wrap all into one macro:
+
+\normalprotected\def\newif#1%
+  {\let\new_if_saved\newif
+   \let\newif\new_if_check
+   \expandafter\def\csname\expandafter\newif\csstring#1true\endcsname {\let#1\iftrue }%
+   \expandafter\def\csname\expandafter\newif\csstring#1false\endcsname{\let#1\iffalse}%
+   \csname\expandafter\newif\csstring#1false\endcsname
+   \let\newif\new_if_saved}
+
+\bgroup
+   \normalexpanded{\gdef\noexpand\new_if_check\string i\string f{}}
+\egroup
+
+%D Let's test this one:
+
+\newif\ifdone
+\newif\iffound
+
+\let\htdp\boxtotal
+
+%D A few shortcuts:
+
+\normalprotected\def\udef {\normalprotected\def }
+\normalprotected\def\ugdef{\normalprotected\gdef}
+\normalprotected\def\uedef{\normalprotected\edef}
+\normalprotected\def\uxdef{\normalprotected\xdef}
+
+%D For a while we keep the following, as systems like tikz need it. Best
+%D not use that one \CONTEXT.
+
+\let\active\activecatcode
+
+%D Constants to be used with \type {\currentgrouptype}.
+
+\chardef\bottomlevelgroupcode   =  0
+\chardef\simplegroupcode        =  1
+\chardef\hboxgroupcode          =  2
+\chardef\adjustedhboxgroupcode  =  3
+\chardef\vboxgroupcode          =  4
+\chardef\vtopgroupcode          =  5
+\chardef\aligngroupcode         =  6
+\chardef\noaligngroupcode       =  7
+\chardef\outputgroupcode        =  8
+\chardef\mathgroupcode          =  9
+\chardef\discretionarygroupcode = 10
+\chardef\insertgroupcode        = 11
+\chardef\vcentergroupcode       = 12
+\chardef\mathchoicegroupcode    = 13
+\chardef\semisimplegroupcode    = 14
+\chardef\mathshiftgroupcode     = 15
+\chardef\mathleftgroupcode      = 16
+\chardef\vadjustgroupcode       = \insertgroupcode
+
+%D Constants to be used with \type {\interactionmode}.
+
+\chardef\batchmodecode     \zerocount
+\chardef\nonstopmodecode   \plusone
+\chardef\scrollmodecode    \plustwo
+\chardef\errorstopmodecode \plusthree
+
+%D Constants to be used with \type {\lastnodetype}. The \type {\lastnodetype}
+%D primitive is \ETEX\ compliant. The valid range is still -1 .. 15 and glyph nodes
+%D have number 0 (used to be char node) and ligature nodes are mapped to 7. That way
+%D macro packages can use the same symbolic names as in traditional \ETEX. Keep in
+%D mind that the internal node numbers are different and that there are more node
+%D types that 15. The mode parameter forces \LUAMETATEX\ to use the real node
+%D numbers.
+
+\internalcodesmode\plusone
+
+%D Constants to be used with \type {\currentiftype}. I wonder if we will ever
+%D use these in \CONTEXT. We have a few more anyway and in \LUAMETATEX\ we
+%D have different numbers. So for now let's just not define them. The
+%D previously mentioned mode parameters enables the real numbers (we have
+%D some more and they are therefore ordered differently).
+
+% \chardef\charifcode     =  1
+% \chardef\catifcode      =  2
+% \chardef\numifcode      =  3
+% \chardef\dimifcode      =  4
+% \chardef\oddifcode      =  5
+% \chardef\vmodeifcode    =  6
+% \chardef\hmodeifcode    =  7
+% \chardef\mmodeifcode    =  8
+% \chardef\innerifcode    =  9
+% \chardef\voidifcode     = 10
+% \chardef\hboxifcode     = 11
+% \chardef\vboxifcode     = 12
+% \chardef\xifcode        = 13
+% \chardef\eofifcode      = 14
+% \chardef\trueifcode     = 15
+% \chardef\falseifcode    = 16
+% \chardef\caseifcode     = 17
+% \chardef\definedifcode  = 18
+% \chardef\csnameifcode   = 19
+% \chardef\fontcharifcode = 20
+
+%D Of course we want even bigger log files, so we copied this from the \ETEX\
+%D source files.
+%D
+%D When watching such logs, beware of nasty side effects of \type {\scantokens},
+%D as in:
+%D
+%D \starttyping
+%D \bgroup
+%D   \lccode`a=12\lowercase{\xdef\whatever{a}}\egroup
+%D   \def\whatever{test \whatever test}
+%D   \scantokens\expandafter{\whatever}
+%D \egroup
+%D \stoptyping
+%D
+%D In \LUATEX\ we have ways around this.
+
+% no longer \errorstopmode cf. plain tex 3.141592653
+
+\normalprotected\def\tracingall
+  {\tracingonline    \plusone
+   \tracingcommands  \plusthree
+   \tracingstats     \plustwo
+   \tracingpages     \plusone
+   \tracingoutput    \plusone
+   \tracinglostchars \plustwo
+   \tracingmacros    \plustwo
+   \tracingparagraphs\plusone
+   \tracingrestores  \plusone
+   \showboxbreadth   \maxdimen
+   \showboxdepth     \maxdimen
+   \tracinggroups    \plusone
+   \tracingifs       \plusone
+   \tracingscantokens\plusone
+   \tracingnesting   \plusone
+   \tracingassigns   \plustwo}
+
+\normalprotected\def\loggingall
+  {\tracingall
+   \tracingonline    \zerocount}
+
+\normalprotected\def\tracingnone
+  {\tracingassigns   \zerocount
+   \tracingnesting   \zerocount
+   \tracingscantokens\zerocount
+   \tracingifs       \zerocount
+   \tracinggroups    \zerocount
+   \showboxdepth     \plusthree
+   \showboxbreadth   \plusfive
+   \tracingrestores  \zerocount
+   \tracingparagraphs\zerocount
+   \tracingmacros    \zerocount
+   \tracinglostchars \plusone
+   \tracingoutput    \zerocount
+   \tracingpages     \zerocount
+   \tracingstats     \zerocount
+   \tracingcommands  \zerocount
+   \tracingonline    \zerocount}
+
+%D When we want to see a box we can as well show all of it.
+
+\showboxdepth  \maxdimen
+\showboxbreadth\maxdimen
+
+%D Just for tracing purposes we set:
+
+\tracingstats\plusone
+
+%D Here we also save \type {\input}, more will be saved later.
+
+\ifdefined\normalinput \else \let\normalinput\input \fi
+
+%D We don't like outer commands, and we always want access to the original
+%D \type {\input} primitive.
+
+\let\normalouter\outer  \def\outer{} % no longer \relax
+
+%D To circumvent dependencies, we can postpone certain initializations to
+%D dumping time, by appending them to the \type {\everydump} token register.
+
+\ifdefined\normaldump \else \let\normaldump\dump \fi
+
+\newtoks\everydump
+
+\def\dump{\the\everydump\normaldump}
+
+%D The same applies for the startup actions.
+
+\ifdefined\normaleveryjob \else \let\normaleveryjob\everyjob \fi
+
+\let\everyjob\relax \newtoks\everyjob
+
+\normaleveryjob{\the\everyjob}
+
+%D \macros
+%D   {newconditional,
+%D    settrue, setfalse,
+%D    ifconditional,then}
+%D
+%D \TEX's lacks boolean variables, although the \PLAIN\ format implements \type
+%D {\newif}. The main disadvantage of this scheme is that it takes three hash table
+%D entries. A more memory saving alternative is presented here. A conditional is
+%D defined by:
+%D
+%D \starttyping
+%D \newconditional\doublesided
+%D \setfalse
+%D \stoptyping
+%D Setting a conditional is done by \type{\settrue} and
+%D \type{\setfalse}:
+%D
+%D \starttyping
+%D \settrue\doublesided
+%D \setfalse
+%D \stoptyping
+%D while testing is accomplished by:
+%D
+%D \starttyping
+%D \ifconditional\doublesided  ... \else ... \fi
+%D \setfalse
+%D \stoptyping
+%D We cannot use the simple scheme:
+%D
+%D \starttyping
+%D \def\settrue #1{\let#1=\iftrue}
+%D \def\setfalse#1{\let#1=\iffalse}
+%D \stoptyping
+%D
+%D Such an implementation gives problems with nested conditionals. The next
+%D implementation is about as fast and just as straightforward:
+
+\let\conditionalfalse\plusone    % maybe we will have a dedicated count/chardef
+\let\conditionaltrue \zerocount  % maybe we will have a dedicated count/chardef
+
+\normalprotected\def\settrue #1{\let#1\conditionaltrue }
+\normalprotected\def\setfalse#1{\let#1\conditionalfalse}
+
+\normalprotected\def\settruevalue #1{\expandafter\let\csname#1\endcsname\conditionaltrue }
+\normalprotected\def\setfalsevalue#1{\expandafter\let\csname#1\endcsname\conditionalfalse}
+
+\let\newconditional\setfalse
+\let\ifconditional \ifcase
+
+\let\then\relax % so that we can say: \ifnum1>2\then -)
+
+% This one has to be unprotected otherwise we get a files-ends-to-soon but it's ok
+% as conditions expand anyway.
+
+\def\quitcondition{\orelse\iffalse}
+
+%D \macros
+%D   {newmacro,setnewmacro,newfraction}
+%D
+%D Let's be complete and also introduce some definers. These are not mandate
+%D but handy for grepping.
+
+\normalprotected\def\newmacro   #1{\let#1\empty}
+\normalprotected\def\setnewmacro#1{\let#1}
+
+\def\!!zerocount{0}
+\def\!!plusone  {1}
+
+\normalprotected\def\newfraction#1{\let#1\!!plusone}
+
+%D It would be handy to have a primitive \type {\unless\ifcase} because then we
+%D could use nicer values. Anyhow, this conditional code used to be in the \type
+%D {syst-aux} module but is now promoted to here.
+
+%D \macros
+%D   {ifzeropt}
+%D
+%D The next macro is both cosmetic and byte saving. It is pretty \type
+%D {\if}||safe too. It can be used in cases like:
+%D
+%D \starttyping
+%D \ifzeropt \somedimen ... \else ... \fi
+%D \stoptyping
+
+\let\ifzeropt\ifcase
+
+% these token list helpers might move to syst-aux.mkiv
+%
+% we assume a \cs. not toks0 or so
+%
+% \normalprotected\def\appendtotoks #1#{\def\temp{#1}\afterassignment\doappendtotoks \scratchtoks=}
+% \normalprotected\def\prependtotoks#1#{\def\temp{#1}\afterassignment\doprependtotoks\scratchtoks=}
+
+\newtoks\t_syst_toks_temp \let\m_syst_toks_temp\t_syst_toks_temp
+
+\normalprotected\def\appendtotoks #1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_append_l \t_syst_toks_temp=}
+\normalprotected\def\prependtotoks#1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_prepend_l\t_syst_toks_temp=}
+
+% \def\syst_toks_append {\m_syst_toks_temp\expandafter\expandafter\expandafter{\expandafter\the\expandafter\m_syst_toks_temp\the\t_syst_toks_temp}}}
+% \def\syst_toks_prepend{\m_syst_toks_temp\expandafter\expandafter\expandafter{\expandafter\the\expandafter\t_syst_toks_temp\the\m_syst_toks_temp}}}
+
+\normalprotected\def\globalappendtotoks #1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_append_g \t_syst_toks_temp=}
+\normalprotected\def\globalprependtotoks#1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_prepend_g\t_syst_toks_temp=}
+
+\def\syst_toks_append_l {\normalexpanded{\m_syst_toks_temp{\the\m_syst_toks_temp\the\t_syst_toks_temp}}}
+\def\syst_toks_prepend_l{\normalexpanded{\m_syst_toks_temp{\the\t_syst_toks_temp\the\m_syst_toks_temp}}}
+
+\def\syst_toks_append_g {\global\syst_toks_append_l }
+\def\syst_toks_prepend_g{\global\syst_toks_prepend_l}
+
+\normalprotected\def\addtotoks      #1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_add_l\let\next}
+\normalprotected\def\globaladdtotoks#1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_add_g\let\next}
+
+\def\syst_toks_add_l{\m_syst_toks_temp\expandafter\bgroup\the\m_syst_toks_temp}
+\def\syst_toks_add_g{\global\syst_toks_add_l}
+
+\normalprotected\def\addtotokscs      #1#2{#1{\the#1#2}}        % saves a few bytes
+\normalprotected\def\globaladdtotokscs#1#2{\global#1{\the#1#2}} % saves a few bytes
+
+%D \macros
+%D   {begcsname}
+%D
+%D Handy for \ETEX-only usage (avoids making \type {\relax}'s:
+
+% \def\begcsname#1\endcsname{\ifcsname#1\endcsname\csname#1\endcsname\fi}
+
+\let\begcsname\begincsname
+
+%D Now come a few macros that might be needed in successive loading. We redefine the
+%D \type {\par} primitive pretty soon so that we get the equivalents right.
+
+% too tricky: \par is use more often than a par starts so we have too much change
+% that we get assymetrical behaviour
+%
+% \newtoks\everyendpar
+%
+% \normalprotected\def\endpar{\the\everyendpar\normalpar}
+% \normalprotected\def\par   {\endpar}
+%
+% \normalprotected\def\reseteverypar
+%   {\everypar   \emptytoks
+%    \everyendpar\emptytoks}
+
+\normalprotected\def\reseteverypar
+  {\everypar\emptytoks}
+
+\let\endgraf\par
+\let\endline\cr
+
+\normalprotected\def\null{\hpack{}}
+
+%D The following two might be overloaded later on but some modules need then
+%D earlier. These functionality is reflected in the name and will not change.
+
+% \bgroup
+%     \catcode`\^^M=\activecatcode%
+%     \gdef\obeylines{\catcode`\^^M\activecatcode \let^^M\par}%
+%     \glet^^M\par%
+% \egroup
+%
+% \bgroup
+%     \gdef\obeyspaces{\catcode`\ \activecatcode}%
+%     \obeyspaces\glet =\space%
+% \egroup
+
+\def\obeylines {\catcode\endoflineasciicode\activecatcode\letcharcode\endoflineasciicode\par}
+\def\obeyspaces{\catcode\spaceasciicode    \activecatcode\letcharcode\spaceasciicode    \space}
+
+% %D A constant:
+%
+% \let\endoflinetoken=^^M
+
+%D Also needed might be a simple loop structure and we borrow plain \TEX's one
+%D as it is often expected to be present and it is about the fastest you can
+%D get. Beware: this macro does not support nested loops. We use a namespace
+%D prefix \type {@@pln}.
+
+\def\loop#1\repeat{\def\@@plnbody{#1}\@@plniterate} % might go
+
+%D The following makes \type {\loop} \unknown\ \type {\if} \unknown\ \type
+%D {\repeat} skippable (clever trick):
+
+\let\repeat\fi % so both \loop and \repeat are reserved words!
+
+%D The original (no \type {@@pln} there):
+%D
+%D \starttyping
+%D \def\@@plniterate{\@@plnbody\let\next\@@plniterate\else\let\next\relax\fi\next}
+%D \stoptyping
+%D
+%D A more efficient alternative:
+%D
+%D \starttyping
+%D \def\@@plniterate{\@@plnbody\expandafter\@@plniterate\else\expandafter\relax\fi}
+%D \stoptyping
+%D
+%D An even more efficient one:
+
+\def\@@plniterate{\@@plnbody\expandafter\@@plniterate\else\fi}
+
+%D We don't define a real output routine yet but at least get rid of pages:
+
+\output{\shipout\box\normalpagebox}
+
+%D Although we don't add pagenumbers yet we alias the default register used
+%D for counting pages:
+
+\countdef\pageno\zerocount \pageno\plusone % first page is number 1
+
+%D Beside the raw counter \type {\pageno} the \type {\folio} macro provides
+%D the value.
+
+\def\folio{\the\pageno} % kind of expected and therefore reserved
+
+%D The following registers are kind of standard and (for the moment) we define
+%D them here. This might change.
+
+\newskip \bigskipamount    \bigskipamount   = 12pt plus 4pt minus 4pt
+\newskip \medskipamount    \medskipamount   =  6pt plus 2pt minus 2pt
+\newskip \smallskipamount  \smallskipamount =  3pt plus 1pt minus 1pt
+
+\baselineskip  = 12pt
+\lineskip      =  1pt
+\lineskiplimit =  0pt
+
+%D Sometimes kerns make more sense than glue but we need to be in the
+%D right mode:
+
+\normalprotected\def\vkern{\ifhmode\par           \fi\kern}
+\normalprotected\def\hkern{\ifvmode\dontleavehmode\fi\kern}
+
+%D Again a few kind-of-extensions the core. These come from plain \TEX\ but
+%D are probably not used in \CONTEXT.
+
+\newskip \hideskip   \hideskip  = -1000pt plus 1fill
+\newskip \centering  \centering = 0pt plus 1000pt minus 1000pt
+
+\def\hidewidth % for alignment entries that can stick out
+  {\hskip\hideskip}
+
+\def\ialign % initialized \halign
+  {\everycr\emptytoks
+   \tabskip\zeroskip
+   \halign}
+
+\newcount \mscount
+
+\def\spanomit{\span\omit} % bypass error message
+
+\def\multispan#1%
+  {\omit
+   \mscount#1\relax
+   \loop
+     \ifnum\mscount>\plusone
+       \spanomit \advance\mscount\minusone
+   \repeat}
+
+\let\nopdfcompression        \relax
+\let\onlypdfobjectcompression\relax
+\let\maximumpdfcompression   \relax
+\let\normalpdfcompression    \relax
+
+%D Basic status stuff.
+
+\newif\ifproductionrun
+
+%D For those who expect this \unknown
+
+\ifx\fmtname   \undefined \def\fmtname   {ConTeXt Initial TeX} \fi
+\ifx\fmtversion\undefined \def\fmtversion{3.1415926}           \fi
+
+%D A few bonus macros:
+
+\def\modulonumber#1#2{\the\numexpr#2-((((#2+(#1/2))/#1)-1)*#1)\relax}
+\def\dividenumber#1#2{\the\numexpr(#2-(#1/2))/#1\relax}
+
+%D These could be set at the \LUA\ end instead:
+
+\edef\texenginename         {\directlua{tex.print(LUATEXENGINE)}}
+\edef\texengineversion      {\directlua{tex.print(LUATEXVERSION)}}
+\edef\texenginefunctionality{\directlua{tex.print(LUATEXFUNCTIONALITY)}}
+
+%D We have no reason not to enable this:
+
+\savingvdiscards\plusone
+
+%D We only can set this one via directives (system.synctex) and we only support
+%D the context variant. This will go away completely.
+
+\newcount\synctex \let\normalsynctex\synctex
+
+%D We get rid of the funny \TEX\ offset defaults of one inch by setting them to zero.
+
+\voffset\zeropoint \let\voffset\relax \newdimen\voffset \let\normalvoffset\voffset
+\hoffset\zeropoint \let\hoffset\relax \newdimen\hoffset \let\normalhoffset\hoffset
+
+\matheqnogapstep\zerocount % for now
+
+%D Now we define a few helpers that we need in a very early stage. We have no
+%D message system yet but redundant definitions are fatal anyway.
+
+\newcount\c_syst_helpers_n_of_namespaces \c_syst_helpers_n_of_namespaces\pluseight % 1-8 reserved for catcodes
+
+\def\v_interfaces_prefix_template_system{\number    \c_syst_helpers_n_of_namespaces>>}
+%def\v_interfaces_prefix_template_system{\characters\c_syst_helpers_n_of_namespaces>>} % no \characters yet
+
+\normalprotected\def\installsystemnamespace#1%
+  {\ifcsname ??#1\endcsname
+     \immediate\write\statuswrite{fatal error: duplicate system namespace '#1'}%
+     \expandafter\normalend
+   \else
+     \global\advance\c_syst_helpers_n_of_namespaces\plusone
+     \expandafter\edef\csname ??#1\endcsname{\v_interfaces_prefix_template_system}%
+   \fi}
+
+%D It makes more sense to have these here:
+
+\let\normalsuperscript  \Usuperscript
+\let\normalsubscript    \Usubscript
+\let\normalnosuperscript\Unosuperscript
+\let\normalnosubscript  \Unosubscript
+\let\normalstartimath   \Ustartmath
+\let\normalstopimath    \Ustopmath
+\let\normalstartdmath   \Ustartdisplaymath
+\let\normalstopdmath    \Ustopdisplaymath
+
+%D Also better here:
+
+\def\wildcardsymbol{*}
+
+\protect \endinput