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+%D \module
+%D   [       file=catc-sym,
+%D        version=1997.01.03, % moved code
+%D          title=\CONTEXT\ Catcode Macros,
+%D       subtitle=Some Handy Constants,
+%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.
+
+% we now have loaded syst-* so we have all @@catcode constants
+
+%D We want to have access to the raw alternatives of the
+%D special characters. We use a \type {\xdef} instead of
+%D \type {\let} because we need an expandable token in a
+%D \type {\write}.
+
+\bgroup
+
+\catcode`B=\begingroupcatcode
+\catcode`E=\endgroupcatcode
+\catcode`.=\escapecatcode
+
+.catcode `.{ 12 .xdef .letteropenbrace       B.string{E
+.catcode `.} 12 .xdef .letterclosebrace      B.string}E
+.catcode `.& 12 .xdef .letterampersand       B.string&E
+.catcode `.< 12 .xdef .letterless            B.string<E
+.catcode `.> 12 .xdef .lettermore            B.string>E
+.catcode `.# 12 .xdef .letterhash            B.string#E
+.catcode `." 12 .xdef .letterdoublequote     B.string"E
+.catcode `.' 12 .xdef .lettersinglequote     B.string'E
+.catcode `.$ 12 .xdef .letterdollar          B.string$E
+.catcode `.% 12 .xdef .letterpercent         B.string%E
+.catcode `.^ 12 .xdef .letterhat             B.string^E
+.catcode `._ 12 .xdef .letterunderscore      B.string_E
+.catcode `.| 12 .xdef .letterbar             B.string|E
+.catcode `.~ 12 .xdef .lettertilde           B.string~E
+.catcode `.\ 12 .xdef .letterbackslash       B.string\E
+.catcode `./ 12 .xdef .letterslash           B.string/E
+.catcode `.? 12 .xdef .letterquestionmark    B.string?E
+.catcode `.! 12 .xdef .letterexclamationmark B.string!E
+.catcode `.@ 12 .xdef .letterat              B.string@E
+.catcode `.: 12 .xdef .lettercolon           B.string:E
+
+         .global .let .letterescape     .letterbackslash
+         .global .let .letterbgroup     .letteropenbrace
+         .global .let .letteregroup     .letterclosebrace
+         .global .let .letterleftbrace  .letteropenbrace
+         .global .let .letterrightbrace .letterclosebrace
+
+.egroup
+
+%D \macros
+%D   {uncatcodespecials,setnaturalcatcodes,setnormalcatcodes,
+%D    uncatcodecharacters,uncatcodeallcharacters,
+%D    uncatcodespacetokens}
+%D
+%D The following macros are more or less replaced by switching
+%D to a catcode table (which we simulate in \MKII) but we keep
+%D them for convenience and compatibility. Some old engine code
+%D has been removed.
+
+\def\uncatcodespecials     {\setcatcodetable\nilcatcodes \uncatcodespacetokens}
+\def\setnaturalcatcodes    {\setcatcodetable\nilcatcodes}
+\def\setnormalcatcodes     {\setcatcodetable\ctxcatcodes} % maybe \texcatcodes
+\def\uncatcodecharacters   {\setcatcodetable\nilcatcodes} % was fast version, gone now
+\def\uncatcodeallcharacters{\setcatcodetable\nilcatcodes} % was slow one, with restore
+
+\def\uncatcodespacetokens
+  {\catcode\spaceasciicode    \spacecatcode
+   \catcode\formfeedasciicode \ignorecatcode
+   \catcode\endoflineasciicode\endoflinecatcode
+   \catcode\delasciicode      \ignorecatcode}
+
+%D \macros
+%D   {setverbosecharacter,setverbosecscharacters}
+%D
+%D Next follows a definition that lets some shortcuts expand to
+%D themselves. This macro is meant for \POSTSCRIPT\ and \PDF\
+%D code passed on to the backend.
+
+\newtoks\everyverbosechacters
+
+\def\setverbosecscharacter#1%
+  {\edef#1{\string#1}}
+
+\def\setverbosecscharacters
+  {\the\everyverbosechacters}
+
+\bgroup
+
+    % if used often we can move the code inline
+
+    \catcode\barasciicode  \activecatcode
+    \catcode\tildeasciicode\activecatcode
+
+    \global \everyverbosechacters =
+      {\setverbosecscharacter |\setverbosecscharacter ~% context specific
+       \setverbosecscharacter\|\setverbosecscharacter\~%
+       \setverbosecscharacter\:\setverbosecscharacter\;%
+       \setverbosecscharacter\+\setverbosecscharacter\-%
+       \setverbosecscharacter\[\setverbosecscharacter\]%
+       \setverbosecscharacter\.\setverbosecscharacter\\%
+       \setverbosecscharacter\)\setverbosecscharacter\(%
+       \setverbosecscharacter\0\setverbosecscharacter\1%
+       \setverbosecscharacter\2\setverbosecscharacter\3%
+       \setverbosecscharacter\4\setverbosecscharacter\5%
+       \setverbosecscharacter\6\setverbosecscharacter\7%
+       \setverbosecscharacter\8\setverbosecscharacter\9%
+       \setverbosecscharacter\n\setverbosecscharacter\s%
+       \setverbosecscharacter\/}
+
+\egroup
+
+%D (Inspired by a discussion on the \CONTEXT\ mailing list)
+%D
+%D In \TEX\ each character can have one of 16 catcodes. This way the
+%D backslash, dollar, ampersand, hash and some more characters get
+%D their  special meaning. If you want to process tokens under a
+%D certain catcode  regime, passing arguments can interfere badly.
+%D
+%D \startbuffer[a]
+%D \def\whatever#1{[#1]}
+%D \whatever{whatever \type {\whatever{you want}} $or$ not!}
+%D \stopbuffer
+%D
+%D \typebuffer[a]
+%D
+%D Here we pass an argument to \type {\whatever} but part of that
+%D argument is to be processed under a different catcode regime, i.e.\
+%D all characters that need to be typeset verbatim need to get
+%D the catcode that makes it a letter. This is what we get when we typeset
+%D the text verbatim:
+%D
+%D \starttyping
+%D whatever \type {\whatever{you want}} $or$ not!
+%D \stoptyping
+%D
+%D However, when passed to \type {\whatever} we get:
+%D
+%D \getbuffer[a]
+%D
+%D In \ETEX\ one can use  \type {\scantokens} to circumvent this problem.
+%D
+%D \startbuffer[b]
+%D \def\rescan#1{\scantokens{#1}}
+%D \def\whatever#1{[\rescan{#1}]}
+%D \whatever{whatever \type {\whatever{you want}} $or$ not!}
+%D \stopbuffer
+%D
+%D \getbuffer[b] \typebuffer[b]
+%D
+%D This time the \type {\whatever} call gives:
+%D
+%D \getbuffer[b]
+%D
+%D In this example, two spaces have crept in. The first one, after the
+%D macro name, is inserted by \TEX\ and cannot be avoided. The last space
+%D is inserted by \type {\scantokens}, and is the consequence of the fact
+%D that this macro mimics reading from a file. You can avoid the last
+%D space by a slightly different definition:
+%D
+%D \startbuffer[c]
+%D \def\rescan#1{\scantokens{#1\ignorespaces}}
+%D \def\whatever#1{[\rescan{#1}]}
+%D \whatever{whatever \type {\whatever{you want}} $or$ not!}
+%D \stopbuffer
+%D
+%D \typebuffer[c]
+%D
+%D Unfortunately we still keep the first space, but at least it's better than
+%D a failure:
+%D
+%D \getbuffer[c]
+
+\long\def\rescan#1{\scantokens{#1\ignorespaces}}
+\long\def\rescanwithsetup#1#2{\begingroup\directsetup{#1}\scantokens{#2\ignorespaces}\endgroup}
+
+\ifx\scantextokens\undefined \else
+  \long\def\rescan#1{\scantextokens{#1}}
+  \long\def\rescanwithsetup#1#2{\begingroup\directsetup{#1}\scantextokens{#2}\endgroup}
+\fi
+
+\endinput