path: root/tex/context/base/mkxl/syst-ini.mkxl

%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.

\immutable\integerdef\escapecatcode             0
\immutable\integerdef\begingroupcatcode         1
\immutable\integerdef\endgroupcatcode           2
\immutable\integerdef\mathshiftcatcode          3
\immutable\integerdef\alignmentcatcode          4
\immutable\integerdef\endoflinecatcode          5
\immutable\integerdef\parametercatcode          6
\immutable\integerdef\superscriptcatcode        7
\immutable\integerdef\subscriptcatcode          8
\immutable\integerdef\ignorecatcode             9
\immutable\integerdef\spacecatcode             10
\immutable\integerdef\lettercatcode            11
\immutable\integerdef\othercatcode             12  % finally obsolete: \let\other \othercatcode
\immutable\integerdef\activecatcode            13  % finally obsolete: \let\active\activecatcode
\immutable\integerdef\commentcatcode           14
\immutable\integerdef\invalidcatcode           15

%immutable\integerdef\zeroasciicode             0
\immutable\integerdef\tabasciicode              9
\immutable\integerdef\newlineasciicode         10  % don't confuse this one with \endoflineasciicode
\immutable\integerdef\formfeedasciicode        12
\immutable\integerdef\endoflineasciicode       13  % somewhat messy but this can be the active \par
\immutable\integerdef\endoffileasciicode       26
\immutable\integerdef\spaceasciicode           32
\immutable\integerdef\exclamationmarkasciicode 33 % ! used in namespace protection
\immutable\integerdef\doublequoteasciicode     34 % "
\immutable\integerdef\hashasciicode            35
\immutable\integerdef\dollarasciicode          36
\immutable\integerdef\commentasciicode         37
\immutable\integerdef\ampersandasciicode       38
\immutable\integerdef\singlequoteasciicode     39 % '
\immutable\integerdef\primeasciicode           39 % '
\immutable\integerdef\leftparentasciicode      40
\immutable\integerdef\rightparentasciicode     41
\immutable\integerdef\commaasciicode           44
\immutable\integerdef\hyphenasciicode          45
\immutable\integerdef\periodasciicode          46
\immutable\integerdef\forwardslashasciicode    47 % /
\immutable\integerdef\colonasciicode           58
\immutable\integerdef\lessthanasciicode        60 % < used as alternative verbatim {
\immutable\integerdef\morethanasciicode        62 % > used as alternative verbatim }
\immutable\integerdef\questionmarkasciicode    63 % ? used in namespace protection
\immutable\integerdef\atsignasciicode          64 % @ used in namespace protection
\immutable\integerdef\leftbracketasciicode     91
\immutable\integerdef\backslashasciicode       92 % `\\
\immutable\integerdef\rightbracketasciicode    93
\immutable\integerdef\circumflexasciicode      94
\immutable\integerdef\underscoreasciicode      95
\immutable\integerdef\leftbraceasciicode      123 % `\{
\immutable\integerdef\barasciicode            124 % `\|
\immutable\integerdef\rightbraceasciicode     125 % `\}
\immutable\integerdef\tildeasciicode          126 % `\~
\immutable\integerdef\delasciicode            127

\aliased\let\percentasciicode\commentasciicode

%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

%D First we need to initialization the primitives. Because \CONTEXT\ is already a
%D pretty old macro package, we have a couple of issues with respect to primitives.
%D The \ETEX\ engine added a few as did \PDFTEX. The \LUATEX\ engine added even
%D more. This means that there can be a potential clash between primitives and
%D existing macros. The most noticeable ones are:
%D
%D \starttyping
%D \protected
%D \expanded
%D \unexpanded
%D \stoptyping
%D
%D Because we had macros like that before the primitives showed up. The protection
%D related macros were there before we even knew about extensions to the engine.
%D When the expansion related ones were introduced, we originally came up with
%D different names but due to requests we used the current names, somethng that in
%D retrospect was a bad idea: they should have gotten different names in \LUATEX, if
%D only because at that time only \CONTEXT\ was using them in rolling releases.
%D Anyway, we're now stuck with this situation, and it means that one should use the
%D \type {\normal...} variants in low level code:
%D
%D \starttyping
%D \normalexpanded
%D \normalprotected
%D \normalunexpanded
%D \stoptyping
%D
%D In the end not using different names in \LUATEX\ for these kind of backfires. It
%D makes not much sense to fix this in \LUAMETATEX\ because we're now to long on the
%D road. It is actually the reason why we have the option in \LUATEX\ to alias all
%D primitives in one go using a prefix. Actually this trick could be used to recover
%D a primitive meaning: just enable it with some prefix and \type {\let} the
%D original to that. But \unknown\ we prevent that trick below.
%D
%D The code below differs from \LUATEX: in \LUAMETATEX\ all primitives are already
%D available; it cannot limit itself to being \TEX\ or \ETEX. It could not do that
%D anyway because there are differences (no backend, to mention one).

\directlua {
    tex.enableprimitives("normal",true) % we default to everything
    function tex.enableprimitives() end % so we kind of protect what's there
}

\permanent\let\undefined\undefined

\immutable\def\space{ }
\immutable\def\empty{}
\mutable  \def\temp {}

\immutable\letcharcode \formfeedasciicode \par    % \def ^^L{\par}  formfeed
\immutable\letcharcode \tildeasciicode    \       %                 tilde
\immutable\letcharcode \spaceasciicode    \space  %                 space

\immutable\defcsname\Uchar\tabasciicode      \endcsname {\ }   % \def\^^I{\ }    tab
\immutable\defcsname\Uchar\formfeedasciicode \endcsname {\par} % \def\^^L{\par}  formfeed
\immutable\defcsname\Uchar\endoflineasciicode\endcsname {\ }   % \def\^^M{\ }    return

%D For now:

\permanent\def\gobbleoneargument#-{} % will be defined later on anyway

%D First we define a simplified version of the \CONTEXT\ protection mechanism. Later
%D 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:

\immutable\let\bgroup={
\immutable\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

% use \chardef instead for min and max
%
% will be blocked: \newfamily \newlanguage

\permanent\countdef   \c_syst_min_allocated_register   =    52 \c_syst_min_allocated_register   =   256 % can change
\permanent\countdef   \c_syst_max_allocated_register   =    53 \c_syst_max_allocated_register   = 65535
\permanent\countdef   \c_syst_min_allocated_read       =    54 \c_syst_min_allocated_read       =     0
\permanent\countdef   \c_syst_max_allocated_read       =    55 \c_syst_max_allocated_read       =  1023
\permanent\countdef   \c_syst_min_allocated_language   =    56 \c_syst_min_allocated_language   =     0
\permanent\countdef   \c_syst_max_allocated_language   =    57 \c_syst_max_allocated_language   =  8191
\permanent\countdef   \c_syst_min_allocated_insert     =    58 \c_syst_min_allocated_insert     =   128
\permanent\countdef   \c_syst_max_allocated_insert     =    59 \c_syst_max_allocated_insert     =   254
\permanent\countdef   \c_syst_min_allocated_family     =    60 \c_syst_min_allocated_family     =   128
\permanent\countdef   \c_syst_max_allocated_family     =    61 \c_syst_max_allocated_family     =   255
\permanent\countdef   \c_syst_min_allocated_attribute  =    62 \c_syst_min_allocated_attribute  =  1024 % 0-1023 : private
\permanent\countdef   \c_syst_min_allocated_write      =    63 \c_syst_min_allocated_write      =     0
\permanent\countdef   \c_syst_max_allocated_write      =    64 \c_syst_max_allocated_write      =  1023

\permanent\countdef   \c_syst_last_allocated_count     =    32 \c_syst_last_allocated_count     = \c_syst_min_allocated_register
\permanent\countdef   \c_syst_last_allocated_dimen     =    33 \c_syst_last_allocated_dimen     = \c_syst_min_allocated_register
\permanent\countdef   \c_syst_last_allocated_skip      =    34 \c_syst_last_allocated_skip      = \c_syst_min_allocated_register
\permanent\countdef   \c_syst_last_allocated_muskip    =    35 \c_syst_last_allocated_muskip    = \c_syst_min_allocated_register
\permanent\countdef   \c_syst_last_allocated_box       =    36 \c_syst_last_allocated_box       = \c_syst_min_allocated_register
\permanent\countdef   \c_syst_last_allocated_toks      =    37 \c_syst_last_allocated_toks      = \c_syst_min_allocated_register
\permanent\countdef   \c_syst_last_allocated_read      =    38 \c_syst_last_allocated_read      = \c_syst_min_allocated_read
\permanent\countdef   \c_syst_last_allocated_write     =    39 \c_syst_last_allocated_write     = \c_syst_min_allocated_write
\permanent\countdef   \c_syst_last_allocated_marks     =    40 \c_syst_last_allocated_marks     = \c_syst_min_allocated_register
\permanent\countdef   \c_syst_last_allocated_language  =    41 \c_syst_last_allocated_language  = \c_syst_min_allocated_language    % not used in context
\permanent\countdef   \c_syst_last_allocated_insertion =    42 \c_syst_last_allocated_insertion = \c_syst_min_allocated_insert
\permanent\countdef   \c_syst_last_allocated_family    =    43 \c_syst_last_allocated_family    = \c_syst_min_allocated_family      % not used in context
\permanent\countdef   \c_syst_last_allocated_attribute =    44 \c_syst_last_allocated_attribute = \c_syst_min_allocated_attribute   % not used in context

\permanent\countdef   \c_syst_min_counter_value =   125 \c_syst_min_counter_value = -"7FFFFFFF % beware, we use index 125 at the lua end
\permanent\countdef   \c_syst_max_counter_value =   126 \c_syst_max_counter_value =  "7FFFFFFF % beware, we use index 126 at the lua end

\immutable\integerdef\zerocount       0
\immutable\integerdef\plusone         1
\immutable\integerdef\minusone       -1

\immutable\integerdef\normalpagebox 255  % hardcoded in pdftex/xetex

\immutable\integerdef\statuswrite   \minusone

%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.

\permanent\let\wlog\gobbleoneargument % Let's get rid of this one.

%D The allocators share a common helper macro.

\permanent\protected\def\newcount   {\syst_basics_allocate\c_syst_last_allocated_count    \count   \countdef  \c_syst_max_allocated_register}
\permanent\protected\def\newdimen   {\syst_basics_allocate\c_syst_last_allocated_dimen    \dimen   \dimendef  \c_syst_max_allocated_register}
\permanent\protected\def\newskip    {\syst_basics_allocate\c_syst_last_allocated_skip     \skip    \skipdef   \c_syst_max_allocated_register}
\permanent\protected\def\newmuskip  {\syst_basics_allocate\c_syst_last_allocated_muskip   \muskip  \muskipdef \c_syst_max_allocated_register}
\permanent\protected\def\newbox     {\syst_basics_allocate\c_syst_last_allocated_box      \box     \integerdef\c_syst_max_allocated_register}
\permanent\protected\def\newtoks    {\syst_basics_allocate\c_syst_last_allocated_toks     \toks    \toksdef   \c_syst_max_allocated_register}
\permanent\protected\def\newread    {\syst_basics_allocate\c_syst_last_allocated_read     \read    \integerdef\c_syst_max_allocated_read}
\permanent\protected\def\newwrite   {\syst_basics_allocate\c_syst_last_allocated_write    \write   \integerdef\c_syst_max_allocated_write}
\permanent\protected\def\newmarks   {\syst_basics_allocate\c_syst_last_allocated_marks    \marks   \integerdef\c_syst_max_allocated_register}
\permanent\protected\def\newinsert  {\syst_basics_allocate\c_syst_last_allocated_insertion\insert  \chardef   \c_syst_max_allocated_insert}
\permanent\protected\def\newlanguage{\syst_basics_allocate\c_syst_last_allocated_language \language\integerdef\c_syst_max_allocated_language} % not needed in context
\permanent\protected\def\newfamily  {\syst_basics_allocate\c_syst_last_allocated_family   \fam     \integerdef\c_syst_max_allocated_family}   % not needed in context

\aliased\let\newfam\newfamily

\firstvalidlanguage \plusone % so zero is ignored in hyphenation, this might become the default

% 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.

\permanent\protected\def\setconstant         {}
\permanent\protected\def\setconstantvalue#1#2{\csname#1\endcsname\numexpr#2\relax}

\permanent\protected\def\newconstant#1%
  {\ifrelax#1%
    %\writestatus{!!!!!!!!!!}{\string #1 => RELAX}%
     \unletfrozen#1%
     \newcount#1%
   \orelse\ifdefined#1%
    %\writestatus{!!!!!!!!!!}{\string #1 => DEFINED}%
   \else
     \newcount#1%
   \fi}

\permanent\protected\def\setnewconstant#1{\newconstant#1#1}

% %D The next definitions are really needed (in \CONTEXT):

\newlinechar\newlineasciicode  \permanent\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
   %\protected\def\writestatus#1#2{\immediate\write\statuswrite{#1: #2}}
    \frozen\protected\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
     \permanent\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
  {\ifrelax#5%
     \expandafter\syst_basics_allocate_yes
   \orelse\ifdefined#5%
     \expandafter\syst_basics_allocate_nop
   \else
     \expandafter\syst_basics_allocate_yes
   \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}.

% \protected\def\newbox  {\syst_basics_allocate\c_syst_last_allocated_box  \box  \chardef\c_syst_max_allocated_register}
% \protected\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.

\immutable\integerdef\attributeunsetvalue\c_syst_min_counter_value % used to be \minusone

% \permanent\protected\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.
%
% \permanent\protected\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

\mutable\let\scratchmacro   \relax
\mutable\let\scratchmacroone\relax
\mutable\let\scratchmacrotwo\relax

%D \macros
%D   {tempstring, scratchstring*}

\mutable\let\tempstring      \empty

\mutable\let\scratchstring   \empty
\mutable\let\scratchstringone\empty
\mutable\let\scratchstringtwo\empty

%D \macros
%D   {scratchwidth, scratchheight, scratchdepth, scratchoffset, scratchdistance}
%D
%D A few more scratch dimensions:

\newdimen\scratchwidth
\newdimen\scratchheight
\newdimen\scratchdepth
\newdimen\scratchtotal

\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:

% \newcount \maxcount      \immutable\maxcount      2147483647

% \newdimen \zeropoint     \immutable\zeropoint     0pt
% \newdimen \onepoint      \immutable\onepoint      1pt
% \newdimen \halfapoint    \immutable\halfapoint    0.5pt
% \newdimen \maxdimen      \immutable\maxdimen      16383.99999pt % 1073741823sp
% \newdimen \onebasepoint  \immutable\onebasepoint  1bp
% \newdimen \scaledpoint   \immutable\scaledpoint   1sp
% \newdimen \thousandpoint \immutable\thousandpoint 1000pt

\immutable\integerdef    \maxcount 2147483647

\immutable\dimensiondef  \zeropoint     0pt
\immutable\dimensiondef  \onepoint      1pt
\immutable\dimensiondef  \halfapoint    0.5pt
\immutable\dimensiondef  \maxdimen      16383.99999pt % 1073741823sp
\immutable\dimensiondef  \onebasepoint  1bp
\immutable\dimensiondef  \scaledpoint   1sp
\immutable\dimensiondef  \thousandpoint 1000pt

\immutable\gluespecdef   \zeroskip      0pt plus 0pt minus 0pt

\immutable\mugluespecdef \zeromuskip    0mu
\immutable\mugluespecdef \onemuskip     1mu
\immutable\mugluespecdef \muquad        18mu

\aliased\let\points   \onepoint
\aliased\let\halfpoint\halfapoint

\newtoks \emptytoks

%D And even more: (todo: countdefs 60+). Watch out, we need a count for a negative constant
%D but can use chardefs for positive ones. Actually, because we have plenty of counters we
%D can also use counts for those.

%immutable\integerdef\minusone              -1
\immutable\integerdef\minustwo              -2
%immutable\integerdef\zerocount              0
%immutable\integerdef\plusone                1
\immutable\integerdef\plustwo                2
\immutable\integerdef\plusthree              3
\immutable\integerdef\plusfour               4
\immutable\integerdef\plusfive               5
\immutable\integerdef\plussix                6
\immutable\integerdef\plusseven              7
\immutable\integerdef\pluseight              8
\immutable\integerdef\plusnine               9
\immutable\integerdef\plusten               10
\immutable\integerdef\pluseleven            11
\immutable\integerdef\plustwelve            12
\immutable\integerdef\plussixteen           16
\immutable\integerdef\plusfifty             50
\immutable\integerdef\plushundred          100
\immutable\integerdef\plusonehundred       100
\immutable\integerdef\plustwohundred       200
\immutable\integerdef\plusfivehundred      500
\immutable\integerdef\pluscxxvii           127
\immutable\integerdef\pluscxxviii          128
\immutable\integerdef\pluscclv             255
\immutable\integerdef\pluscclvi            256
\immutable\integerdef\plusthousand        1000
\immutable\integerdef\plustenthousand    10000
\immutable\integerdef\plustwentythousand 20000
\immutable\integerdef\medcard            32768
\immutable\integerdef\maxcard            65536 % pdftex has less mathchars
\immutable\integerdef\maxcardminusone    65535

%D \macros
%D   {doubleexpandafter,tripleexpandafter,expanded,startexpanded}
%D
%D A few handy shortcuts

\permanent\let\singleexpandafter \expandafter
\permanent\def\doubleexpandafter{\expandafter\expandafter\expandafter}
\permanent\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

\permanent\def\unvoidbox{\unhbox\voidbox}
\permanent\def\emptybox {\box   \voidbox}  % used in initializations so no attributes
\permanent\def\emptyvbox{\normalvpack{}}   % no copy as we need to set attributes
\permanent\def\emptyhbox{\normalhpack{}}   % no copy as we need to set attributes

\aliased\let\leavevmode\unvoidbox % we prefer to use \dontleavehmode

%D \macros
%D   {dontcomplain}
%D
%D We need this one soon:

\permanent\protected\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.

\aliased\let\p@     \onepoint
\aliased\let\m@ne   \minusone
\aliased\let\z@     \zeropoint
\aliased\let\@ne    \plusone
\aliased\let\tw@    \plustwo
\aliased\let\thr@@  \plusthree
\aliased\let\sixt@@n\plussixteen
\aliased\let\@cclv  \pluscclv
\aliased\let\@cclvi \pluscclvi
\aliased\let\voidb@x\voidbox

\newtoks    \toks@  %scratchtoks

%D We define \type {\newif} a la plain \TEX, but will redefine it later. As Knuth
%D 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

% \protected\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.
%
% \protected\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}
%
% \protected\def\new_if_cs#1#2%
%   {\csname\expandafter\newif\csstring#1#2\endcsname}
%
% We wrap all into one macro (the frozen stuff adds 10% runtime):

\permanent\protected\def\newif#1%
  {\permanent\protected\gdefcsname\expandafter\new_if_check\csstring#1true\endcsname {\overloaded\frozen\let#1\iftrue }%
   \permanent\protected\gdefcsname\expandafter\new_if_check\csstring#1false\endcsname{\overloaded\frozen\let#1\iffalse}%
   \csname\expandafter\new_if_check\csstring#1false\endcsname}

\normalexpanded{\gdef\noexpand\new_if_check\string i\string f{}}

%D Let's test this one:

\newif\ifdone
\newif\iffound

\newif\ifscratchcondition
\newif\ifscratchconditionone
\newif\ifscratchconditiontwo

\aliased\let\htdp\boxtotal

%D A few shortcuts:

% \permanent\protected\def\udef {\protected\def }
% \permanent\protected\def\ugdef{\protected\gdef}
% \permanent\protected\def\uedef{\protected\edef}
% \permanent\protected\def\uxdef{\protected\xdef}

% For now:

\permanent\protected\def\defUmathtopaccent  #1#2#3#4{\global\immutable\protected\def#1{\Umathaccent     "#2 "#3 "#4 }}
\permanent\protected\def\defUmathbotaccent  #1#2#3#4{\global\immutable\protected\def#1{\Umathbotaccent  "#2 "#3 "#4 }}
\permanent\protected\def\defUdelimiterover  #1#2#3#4{\global\immutable\protected\def#1{\Udelimiterover  "#2 "#3     }}
\permanent\protected\def\defUdelimiterunder #1#2#3#4{\global\immutable\protected\def#1{\Udelimiterunder "#2 "#3     }}
\permanent\protected\def\defUdelimiter      #1#2#3#4{\global\immutable\protected\def#1{\Udelimiter      "#2 "#3 "#4 }}
\permanent\protected\def\defUradical          #1#2#3{\global\immutable\protected\def#1{\Uradical        "#2 "#3     }}
\permanent\protected\def\defUroot             #1#2#3{\global\immutable\protected\def#1{\Uroot           "#2 "#3     }}
\permanent\protected\def\defUmathchar       #1#2#3#4{\global\immutable\Umathchardef #1                  "#2 "#3 "#4 }

%D For a while we keep the following, as systems like tikz need it. Best not use
%D that one \CONTEXT.

\aliased\let\active\activecatcode

%D Constants to be used with \type {\interactionmode}.

\immutable\integerdef\batchmodecode     \zerocount
\immutable\integerdef\nonstopmodecode   \plusone
\immutable\integerdef\scrollmodecode    \plustwo
\immutable\integerdef\errorstopmodecode \plusthree

%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

\permanent\protected\def\tracingall
  {\tracingonline    \plusone
   \tracingcommands  \plusthree
   \tracingmacros    \plustwo
   \tracingoutput    \plusone
   \tracingpages     \plusone
   \tracingparagraphs\plusone
   \tracingrestores  \plusone
   \tracinggroups    \plusone
   \tracingifs       \plusone
   \tracingnesting   \plustwo
   \tracingassigns   \plustwo
   \tracingmath      \plusone
   \tracingalignments\plusone
   \showboxbreadth   \maxcount
   \showboxdepth     \maxcount}

\permanent\protected\def\loggingall
  {\tracingall
   \tracingonline    \zerocount}

\permanent\protected\def\tracingnone
  {\showboxdepth     \plusthree
   \showboxbreadth   \plusfive
   \tracingalignments\zerocount
   \tracingmath      \zerocount
   \tracingassigns   \zerocount
   \tracingnesting   \zerocount
   \tracingifs       \zerocount
   \tracinggroups    \zerocount
   \tracingrestores  \zerocount
   \tracingparagraphs\zerocount
   \tracingpages     \zerocount
   \tracingoutput    \zerocount
   \tracingmacros    \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 This is only used when we load \CONTEXT. Nesting is not supported here.

\permanent\def\pushoverloadmode
  {\enforced\permanent\protected\edef\popoverloadmode{\overloadmode\the\overloadmode\enforced\let\popoverloadmode\relax}%
   \overloadmode\zerocount}

\aliased\let\popoverloadmode\relax

\let\pushrunstate\relax % will be defined later
\let\poprunstate \relax % will be defined later

\newtoks\everydump

\pushoverloadmode

\permanent\protected\def\dump
  {\the\everydump
   \global\everydump\emptytoks
   \pushoverloadmode
   \enforced\glet\dump\relax
   \popoverloadmode
   %let\pushoverloadmode\relax
   %let\popoverloadmode\relax
 % \tracingall
   \normaldump}

\permanent\protected\def\input
  {\normalinput}

\popoverloadmode

%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:

\aliased\let\conditionalfalse\plusone    % maybe we will have a dedicated count/chardef
\aliased\let\conditionaltrue \zerocount  % maybe we will have a dedicated count/chardef

% \permanent\protected\def\settrue #1{\integerdef#1\conditionaltrue }
% \permanent\protected\def\setfalse#1{\integerdef#1\conditionalfalse}
%
% \permanent\protected\def\settruevalue #1{\expandafter\integerdef\csname#1\endcsname\conditionaltrue }
% \permanent\protected\def\setfalsevalue#1{\expandafter\integerdef\csname#1\endcsname\conditionalfalse}

\permanent\protected\def\settrue       #1{\enforced\let#1\conditionaltrue }
\permanent\protected\def\setfalse      #1{\enforced\let#1\conditionalfalse}
\permanent\protected\def\setconditional#1{\enforced\let#1}

\permanent\protected\def\settruevalue #1{\enforced\letcsname#1\endcsname\conditionaltrue }
\permanent\protected\def\setfalsevalue#1{\enforced\letcsname#1\endcsname\conditionalfalse}


\aliased\let\newconditional\setfalse
\aliased\let\ifconditional \ifcase

\aliased\let\then\relax % so that we can say: \ifnum1>2\then -)

\permanent\def\truecondition {\iftrue}
\permanent\def\falsecondition{\iffalse}

% This one has to be unprotected otherwise we get a files-ends-to-soon but it's ok
% as conditions expand anyway.

\permanent\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. We make these mutable because they are \type
%D {\let} (the only advantage is that we often give them names with some
%D prefix.

\permanent\protected\def\newmacro   #1{\mutable\let#1\empty}
\permanent\protected\def\setnewmacro#1{\mutable\let#1}

\permanent\protected\def\newfraction#1{\mutable\let#1\!!plusone}

\def\!!zerocount{0} % later redefined
\def\!!plusone  {1} % later redefined

%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

\aliased\let\ifzeropt\ifcase

% these token list helpers might move to syst-aux.mkiv
%
% we assume a \cs. not toks0 or so
%
% \protected\def\appendtotoks #1#{\def\temp{#1}\afterassignment\doappendtotoks \scratchtoks=}
% \protected\def\prependtotoks#1#{\def\temp{#1}\afterassignment\doprependtotoks\scratchtoks=}

\newtoks\t_syst_toks_temp \let\m_syst_toks_temp\t_syst_toks_temp

\permanent\protected\def\appendtotoks #1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_append_l \t_syst_toks_temp=}
\permanent\protected\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}}}

\permanent\protected\def\globalappendtotoks #1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_append_g \t_syst_toks_temp=}
\permanent\protected\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}

\permanent\protected\def\addtotoks      #1{\let\m_syst_toks_temp#1\afterassignment\syst_toks_add_l\let\next}
\permanent\protected\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}

\permanent\protected\def\addtotokscs      #1#2{#1{\the#1#2}}        % saves a few bytes
\permanent\protected\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}

\aliased\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
%
% \protected\def\endpar{\the\everyendpar\normalpar}
% \protected\def\par   {\endpar}
%
% \protected\def\reseteverypar
%   {\everypar   \emptytoks
%    \everyendpar\emptytoks}

\permanent\protected\def\reseteverypar
  {\everypar\emptytoks}

\aliased\let\endgraf\par % plain, a kind of funny name
%aliased\let\endline\cr  % plain, not needed and probably also confusing

\permanent\protected\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  } % check if these can be \permanent
\def\obeyspaces{\catcode\spaceasciicode    \activecatcode\letcharcode\spaceasciicode    \space} % check if these can be \permanent

% %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}.

\let\syst_plain_body\relax

\permanent\def\loop#1\repeat{\def\syst_plain_body{#1}\syst_plain_iterate} % might go

%D The following makes \type {\loop} \unknown\ \type {\if} \unknown\ \type
%D {\repeat} skippable (clever trick):

\permanent\let\repeat\fi % so both \loop and \repeat are reserved words!

%D The original (no \type {syst_plain_} there):
%D
%D \starttyping
%D \def\syst_plain_iterate
%D   {\syst_plain_body
%D    \let\next\syst_plain_iterate
%D    \else
%D      \let\next\relax
%D    \fi
%D    \next}
%D \stoptyping
%D
%D A more efficient alternative:
%D
%D \starttyping
%D \def\syst_plain_iterate
%D   {\syst_plain_body
%D    \expandafter\syst_plain_iterate
%D    \else\expandafter\relax\fi}
%D \stoptyping
%D
%D An even more efficient one:

\def\syst_plain_iterate
  {\syst_plain_body
   \expandafter\syst_plain_iterate\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:

\permanent\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.

\permanent\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:

\permanent\protected\def\vkern   {\ifhmode\par           \fi\kern}
\permanent\protected\def\hkern   {\ifvmode\dontleavehmode\fi\kern}

\permanent\protected\def\vpenalty{\ifhmode\par           \fi\penalty}
\permanent\protected\def\hpenalty{\ifvmode\dontleavehmode\fi\penalty}

%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

\permanent\def\hidewidth % for alignment entries that can stick out
  {\hskip\hideskip}

\permanent\def\ialign % initialized \halign
  {\everycr\emptytoks
   \tabskip\zeroskip
   \halign}

\newcount \mscount

\permanent\def\spanomit{\span\omit} % bypass error message

\permanent\def\multispan#1%
  {\omit
   \mscount#1\relax
   \loop
     \ifnum\mscount>\plusone
       \spanomit \advance\mscount\minusone
   \repeat}

\let\nopdfcompression        \relax % later
\let\onlypdfobjectcompression\relax % later
\let\maximumpdfcompression   \relax % later
\let\normalpdfcompression    \relax % later

%D Basic status stuff.

% \newif\ifproductionrun % already defined

%D For those who expect this \unknown

\ifdefined\fmtname    \else \immutable\def\fmtname   {ConTeXt Initial TeX} \fi
\ifdefined\fmtversion \else \immutable\def\fmtversion{3.1415926}           \fi

%D A few bonus macros:

%permanent\def\modulonumber#1#2{\the\numexpr#2-((((#2+(#1/2))/#1)-1)*#1)\relax}
\permanent\def\modulonumber#1#2{\the\numexpr#2-(#2:#1)*#1\relax}
\permanent\def\dividenumber#1#2{\the\numexpr(#2-(#1/2))/#1\relax}

%D These could be set at the \LUA\ end instead:

\immutable\edef\texenginename         {\directlua{tex.print(LUATEXENGINE)}}
\immutable\edef\texengineversion      {\directlua{tex.print(LUATEXVERSION)}}
\immutable\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 \overloaded\let\voffset\relax \newdimen\voffset \let\normalvoffset\voffset
% \hoffset\zeropoint \overloaded\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

\protected\def\installsystemnamespace#1% will be redefined
  {\ifcsname ??#1\endcsname
     \immediate\write\statuswrite{fatal error: duplicate system namespace '#1'}%
   \else
     \global\advance\c_syst_helpers_n_of_namespaces\plusone
     \immutable\edefcsname ??#1\endcsname{\v_interfaces_prefix_template_system}%
   \fi}

%D It makes more sense to have these here:

\aliased\let\normalsuperscript  \Usuperscript
\aliased\let\normalsubscript    \Usubscript
\aliased\let\normalnosuperscript\Unosuperscript
\aliased\let\normalnosubscript  \Unosubscript
\aliased\let\normalstartimath   \Ustartmath
\aliased\let\normalstopimath    \Ustopmath
\aliased\let\normalstartdmath   \Ustartdisplaymath
\aliased\let\normalstopdmath    \Ustopdisplaymath

%D Also better here:

\immutable\def\wildcardsymbol{*}

%D For a while we will keep these useless numbers as for instance tikz checks for them:

\immutable\integerdef\eTeXversion   2
\immutable\def       \eTeXrevision {2}

%D Experiment:

\glyphoptions"80 % replaces \glyphdimensionsmode=1

%D Just in case users use this:

\aliased\let\immediateassign  \immediate
\aliased\let\immediateassigned\localcontrolled

%D Needed:

\mutable\let\nexttoken   \relax
\mutable\let\next        \relax
\mutable\let\nextnext    \relax
\mutable\let\nextnextnext\relax

%D For now here: will get a proper solution

% \pushoverloadmode
% \mutable\let\par\par
% \popoverloadmode

%D Also here:

\listcallbackmode\plusone

%D Often used as cs key:

\mutable\let\on  \empty
\mutable\let\of  \empty
\mutable\let\and \empty
\mutable\let\with\empty
\mutable\let\nop \empty % used often
\mutable\let\yes \empty % used often

%D Another experiment:

\def\syst_suggested_alias#1#2% expandable
  {\beginlocalcontrol
   \writestatus{suggestion}{use \string#2 instead of \string#1}%
   \enforced\glet#1#2%
   \endlocalcontrol
   #2}

\permanent\protected\def\suggestedalias#1#2%
  {\ifflags#2\permanent\permanent\fi % the rest is taken with the copy
   \def#1{\syst_suggested_alias#1#2}}

% 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

\suggestedalias \count@   \scratchcounter
\suggestedalias \dimen@   \scratchdimen
\suggestedalias \dimen@i  \scratchdimenone
\suggestedalias \dimen@ii \scratchdimentwo

%D The next feature is experimental and could go into another system module, but it
%D feels more natural to have it here.
%D
%D \starttyping
%D \begingroup
%D   \newlocaldimen\mydimena % \mydimena1\onepoint
%D   \newlocaldimen\mydimenb % \mydimenb2\onepoint
%D   \begingroup
%D     \newlocaldimen\mydimena % \mydimena3\onepoint
%D     \newlocaldimen\mydimenb % \mydimenb4\onepoint
%D     \newlocaldimen\mydimenc % \mydimenc5\onepoint
%D   \endgroup
%D \endgroup
%D
%D \begingroup
%D   \setlocaldimen\mydimena 1\onepoint
%D   \setlocaldimen\mydimenb 2\onepoint
%D   \begingrou
%D     \setlocaldimen\mydimena 3\onepoint
%D     \setlocaldimen\mydimenb 4\onepoint
%D     \setlocaldimen\mydimenc 5\onepoint
%D   \endgroup
%D \endgroup
%D \stoptyping
%D
%D There is a little extra overhead in the overload protection but not that much.
%D Instead of:

% \newcount\c_syst_local_count \c_syst_local_count \c_syst_max_allocated_register
% \newcount\c_syst_local_dimen \c_syst_local_dimen \c_syst_local_count
% \newcount\c_syst_local_skip  \c_syst_local_skip  \c_syst_local_count
% \newcount\c_syst_local_muskip\c_syst_local_muskip\c_syst_local_count
% \newcount\c_syst_local_box   \c_syst_local_box   \c_syst_local_count
% \newcount\c_syst_local_toks  \c_syst_local_toks  \c_syst_local_count

%D We do this:

\permanent\countdef\c_syst_local_count  = 72 \c_syst_local_count  = \c_syst_max_allocated_register
\permanent\countdef\c_syst_local_dimen  = 73 \c_syst_local_dimen  = \c_syst_local_count
\permanent\countdef\c_syst_local_skip   = 74 \c_syst_local_skip   = \c_syst_local_count
\permanent\countdef\c_syst_local_muskip = 75 \c_syst_local_muskip = \c_syst_local_count
\permanent\countdef\c_syst_local_box    = 76 \c_syst_local_box    = \c_syst_local_count
\permanent\countdef\c_syst_local_toks   = 77 \c_syst_local_toks   = \c_syst_local_count
\permanent\countdef\c_syst_local_read   = 78 \c_syst_local_read   = \c_syst_local_count
\permanent\countdef\c_syst_local_write  = 79 \c_syst_local_write  = \c_syst_local_count

% We should have used  \c_syst_local_dimen = \numexpr \c_syst_max_allocated_register +
% 1\relax, but we do this instead (it's no problem loosing a few registers).

\c_syst_max_allocated_register \numexpr\c_syst_max_allocated_register:2\relax % floor

\permanent\protected\def\syst_local_overflow#1#2{\writestatus\m!system{no room for local #1 \string#2}\wait}

\permanent\protected\def\setnewlocaldimen#1%
  {\ifnum\c_syst_local_dimen>\c_syst_max_allocated_register
     \advance\c_syst_local_dimen\minusone\dimendef#1\c_syst_local_dimen
   \else
     \syst_local_overflow_dimen#1%
   \fi
   #1}

\permanent\protected\def\setnewlocalcount#1%
  {\ifnum\c_syst_local_count>\c_syst_max_allocated_register
     \advance\c_syst_local_count\minusone
     \overloaded\frozen\countdef#1\c_syst_local_count
   \else
     \syst_local_overflow_count#1%
   \fi
   #1}

\permanent\protected\def\setnewlocalskip#1%
  {\ifnum\c_syst_local_skip>\c_syst_max_allocated_register
     \advance\c_syst_local_skip\minusone
     \overloaded\frozen\skipdef#1\c_syst_local_skip
   \else
     \syst_local_overflow_skip#1%
   \fi
   #1}

\permanent\protected\def\setnewlocalmuskip#1%
  {\ifnum\c_syst_local_muskip>\c_syst_max_allocated_register
     \advance\c_syst_local_muskip\minusone
     \overloaded\frozen\muskipdef#1\c_syst_local_muskip
   \else
     \syst_local_overflow_muskip#1%
   \fi
   #1}

\permanent\protected\def\setnewlocaltoks#1%
  {\ifnum\c_syst_local_toks>\c_syst_max_allocated_register
     \advance\c_syst_local_toks\minusone
     \overloaded\frozen\toksdef#1\c_syst_local_toks
   \else
     \syst_local_overflow_toks#1%
   \fi
   #1}

\permanent\protected\def\setnewlocalbox#1%
  {\ifnum\c_syst_local_box>\c_syst_max_allocated_register
     \advance\c_syst_local_box\minusone
     \overloaded\frozen\integerdef#1\c_syst_local_box
   \else
     \syst_local_overflow_box#1%
   \fi
   \setbox#1}

\permanent\protected\def\newlocalread#1% so no set
  {\ifnum\c_syst_local_read>\c_syst_max_allocated_register
     \advance\c_syst_local_read\minusone
     \overloaded\frozen\integerdef#1\c_syst_local_read
   \else
     \syst_local_overflow_read#1%
   \fi}

\permanent\protected\def\newlocalwrite#1% so no set
  {\ifnum\c_syst_local_write>\c_syst_max_allocated_register
     \advance\c_syst_local_write\minusone
     \overloaded\frozen\integerdef#1\c_syst_local_write
   \else
     \syst_local_overflow_write#1%
   \fi}

%D The error handlers:

\permanent\protected\def\syst_local_overflow_count {\syst_local_overflow {count}}
\permanent\protected\def\syst_local_overflow_dimen {\syst_local_overflow {dimen}}
\permanent\protected\def\syst_local_overflow_skip  {\syst_local_overflow  {skip}}
\permanent\protected\def\syst_local_overflow_muskip{\syst_local_overflow{muskip}}
\permanent\protected\def\syst_local_overflow_toks  {\syst_local_overflow  {toks}}
\permanent\protected\def\syst_local_overflow_box   {\syst_local_overflow   {box}}
\permanent\protected\def\syst_local_overflow_read  {\syst_local_overflow  {read}}
\permanent\protected\def\syst_local_overflow_write {\syst_local_overflow {write}}

%D We sacrifice a little performance but save some tokens by not defineing these
%D completely:

\permanent\protected\def\newlocalcount #1{\setnewlocalcount #1\zerocount }
\permanent\protected\def\newlocaldimen #1{\setnewlocaldimen #1\zeropoint }
\permanent\protected\def\newlocalskip  #1{\setnewlocalskip  #1\zeroskip  }
\permanent\protected\def\newlocalmuskip#1{\setnewlocalmuskip#1\zeromuskip}
\permanent\protected\def\newlocaltoks  #1{\setnewlocaltoks  #1\emptytoks }
\permanent\protected\def\newlocalbox   #1{\setnewlocalbox   #1\emptybox  }

%D Let's be detailed: grouplevel:inputlevel:

\tracinglevels\plusthree

%D We just report duplicate patterns being ignored:

\tracinghyphenation\plusone

\protect \endinput