% texinfo.tex -- TeX macros to handle Texinfo files.

 %

 % Load plain if necessary, i.e., if running under initex.

 \expandafter\ifx\csname fmtname\endcsname\relax\input plain\fi

 %

 \def\texinfoversion{2003-07-28.08}

 %

 % Copyright (C) 1985, 1986, 1988, 1990, 1991, 1992, 1993, 1994, 1995,

 % 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.

 %

 % This texinfo.tex file is free software; you can redistribute it and/or

 % modify it under the terms of the GNU General Public License as

 % published by the Free Software Foundation; either version 2, or (at

 % your option) any later version.

 %

 % This texinfo.tex file is distributed in the hope that it will be

 % useful, but WITHOUT ANY WARRANTY; without even the implied warranty

 % of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 % General Public License for more details.

 %

 % You should have received a copy of the GNU General Public License

 % along with this texinfo.tex file; see the file COPYING.  If not, write

 % to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 % Boston, MA 02111-1307, USA.

 %

 % In other words, you are welcome to use, share and improve this program.

 % You are forbidden to forbid anyone else to use, share and improve

 % what you give them.   Help stamp out software-hoarding!

 %

 % Please try the latest version of texinfo.tex before submitting bug

 % reports; you can get the latest version from:

 %   ftp://ftp.gnu.org/gnu/texinfo/texinfo.tex

 %     (and all GNU mirrors, see http://www.gnu.org/order/ftp.html)

 %   ftp://tug.org/tex/texinfo.tex

 %     (and all CTAN mirrors, see http://www.ctan.org),

 %   and /home/gd/gnu/doc/texinfo.tex on the GNU machines.

 %

 % The GNU Texinfo home page is http://www.gnu.org/software/texinfo.

 %

 % The texinfo.tex in any given Texinfo distribution could well be out

 % of date, so if that's what you're using, please check.

 %

 % Send bug reports to bug-texinfo@gnu.org.  Please include including a

 % complete document in each bug report with which we can reproduce the

 % problem.  Patches are, of course, greatly appreciated.

 %

 % To process a Texinfo manual with TeX, it's most reliable to use the

 % texi2dvi shell script that comes with the distribution.  For a simple

 % manual foo.texi, however, you can get away with this:

 %   tex foo.texi

 %   texindex foo.??

 %   tex foo.texi

 %   tex foo.texi

 %   dvips foo.dvi -o  # or whatever; this makes foo.ps.

 % The extra TeX runs get the cross-reference information correct.

 % Sometimes one run after texindex suffices, and sometimes you need more

 % than two; texi2dvi does it as many times as necessary.

 %

 % It is possible to adapt texinfo.tex for other languages, to some

 % extent.  You can get the existing language-specific files from the

 % full Texinfo distribution.

 \message{Loading texinfo [version \texinfoversion]:}

 % If in a .fmt file, print the version number

 % and turn on active characters that we couldn't do earlier because

 % they might have appeared in the input file name.

 \everyjob{\message{[Texinfo version \texinfoversion]}%

   \catcode`+=\active \catcode`\_=\active}

 \message{Basics,}

 \chardef\other=12

 % We never want plain's \outer definition of \+ in Texinfo.

 % For @tex, we can use \tabalign.

 \let\+ = \relax

 % Save some plain tex macros whose names we will redefine.

 \let\ptexb=\b

 \let\ptexbullet=\bullet

 \let\ptexc=\c

 \let\ptexcomma=\,

 \let\ptexdot=\.

 \let\ptexdots=\dots

 \let\ptexend=\end

 \let\ptexequiv=\equiv

 \let\ptexexclam=\!

 \let\ptexgtr=>

 \let\ptexhat=^

 \let\ptexi=\i

 \let\ptexindent=\indent

 \let\ptexlbrace=\{

 \let\ptexless=<

 \let\ptexplus=+

 \let\ptexrbrace=\}

 \let\ptexslash=\/

 \let\ptexstar=\*

 \let\ptext=\t

 % If this character appears in an error message or help string, it

 % starts a new line in the output.

 \newlinechar = `^^J

 % Set up fixed words for English if not already set.

 \ifx\putwordAppendix\undefined  \gdef\putwordAppendix{Appendix}\fi

 \ifx\putwordChapter\undefined   \gdef\putwordChapter{Chapter}\fi

 \ifx\putwordfile\undefined      \gdef\putwordfile{file}\fi

 \ifx\putwordin\undefined        \gdef\putwordin{in}\fi

 \ifx\putwordIndexIsEmpty\undefined     \gdef\putwordIndexIsEmpty{(Index is empty)}\fi

 \ifx\putwordIndexNonexistent\undefined \gdef\putwordIndexNonexistent{(Index is nonexistent)}\fi

 \ifx\putwordInfo\undefined      \gdef\putwordInfo{Info}\fi

 \ifx\putwordInstanceVariableof\undefined \gdef\putwordInstanceVariableof{Instance Variable of}\fi

 \ifx\putwordMethodon\undefined  \gdef\putwordMethodon{Method on}\fi

 \ifx\putwordNoTitle\undefined   \gdef\putwordNoTitle{No Title}\fi

 \ifx\putwordof\undefined        \gdef\putwordof{of}\fi

 \ifx\putwordon\undefined        \gdef\putwordon{on}\fi

 \ifx\putwordpage\undefined      \gdef\putwordpage{page}\fi

 \ifx\putwordsection\undefined   \gdef\putwordsection{section}\fi

 \ifx\putwordSection\undefined   \gdef\putwordSection{Section}\fi

 \ifx\putwordsee\undefined       \gdef\putwordsee{see}\fi

 \ifx\putwordSee\undefined       \gdef\putwordSee{See}\fi

 \ifx\putwordShortTOC\undefined  \gdef\putwordShortTOC{Short Contents}\fi

 \ifx\putwordTOC\undefined       \gdef\putwordTOC{Table of Contents}\fi

 %

 \ifx\putwordMJan\undefined \gdef\putwordMJan{January}\fi

 \ifx\putwordMFeb\undefined \gdef\putwordMFeb{February}\fi

 \ifx\putwordMMar\undefined \gdef\putwordMMar{March}\fi

 \ifx\putwordMApr\undefined \gdef\putwordMApr{April}\fi

 \ifx\putwordMMay\undefined \gdef\putwordMMay{May}\fi

 \ifx\putwordMJun\undefined \gdef\putwordMJun{June}\fi

 \ifx\putwordMJul\undefined \gdef\putwordMJul{July}\fi

 \ifx\putwordMAug\undefined \gdef\putwordMAug{August}\fi

 \ifx\putwordMSep\undefined \gdef\putwordMSep{September}\fi

 \ifx\putwordMOct\undefined \gdef\putwordMOct{October}\fi

 \ifx\putwordMNov\undefined \gdef\putwordMNov{November}\fi

 \ifx\putwordMDec\undefined \gdef\putwordMDec{December}\fi

 %

 \ifx\putwordDefmac\undefined    \gdef\putwordDefmac{Macro}\fi

 \ifx\putwordDefspec\undefined   \gdef\putwordDefspec{Special Form}\fi

 \ifx\putwordDefvar\undefined    \gdef\putwordDefvar{Variable}\fi

 \ifx\putwordDefopt\undefined    \gdef\putwordDefopt{User Option}\fi

 \ifx\putwordDeftypevar\undefined\gdef\putwordDeftypevar{Variable}\fi

 \ifx\putwordDeffunc\undefined   \gdef\putwordDeffunc{Function}\fi

 \ifx\putwordDeftypefun\undefined\gdef\putwordDeftypefun{Function}\fi

 % In some macros, we cannot use the `\? notation---the left quote is

 % in some cases the escape char.

 \chardef\colonChar = `\:

 \chardef\commaChar = `\,

 \chardef\dotChar   = `\.

 \chardef\equalChar = `\=

 \chardef\exclamChar= `\!

 \chardef\questChar = `\?

 \chardef\semiChar  = `\;

 \chardef\spaceChar = `\ %

 \chardef\underChar = `\_

 % Ignore a token.

 %

 \def\gobble#1{}

 % True if #1 is the empty string, i.e., called like `\ifempty{}'.

 %

 \def\ifempty#1{\ifemptyx #1\emptymarkA\emptymarkB}%

 \def\ifemptyx#1#2\emptymarkB{\ifx #1\emptymarkA}%

 % Hyphenation fixes.

 \hyphenation{ap-pen-dix}

 \hyphenation{eshell}

 \hyphenation{mini-buf-fer mini-buf-fers}

 \hyphenation{time-stamp}

 \hyphenation{white-space}

 % Margin to add to right of even pages, to left of odd pages.

 \newdimen\bindingoffset

 \newdimen\normaloffset

 \newdimen\pagewidth \newdimen\pageheight

 % Sometimes it is convenient to have everything in the transcript file

 % and nothing on the terminal.  We don't just call \tracingall here,

 % since that produces some useless output on the terminal.  We also make

 % some effort to order the tracing commands to reduce output in the log

 % file; cf. trace.sty in LaTeX.

 %

 \def\gloggingall{\begingroup \globaldefs = 1 \loggingall \endgroup}%

 \def\loggingall{%

   \tracingstats2

   \tracingpages1

   \tracinglostchars2  % 2 gives us more in etex

   \tracingparagraphs1

   \tracingoutput1

   \tracingmacros2

   \tracingrestores1

   \showboxbreadth\maxdimen \showboxdepth\maxdimen

   \ifx\eTeXversion\undefined\else % etex gives us more logging

     \tracingscantokens1

     \tracingifs1

     \tracinggroups1

     \tracingnesting2

     \tracingassigns1

   \fi

   \tracingcommands3  % 3 gives us more in etex

   \errorcontextlines\maxdimen

 }%

 % add check for \lastpenalty to plain's definitions.  If the last thing

 % we did was a \nobreak, we don't want to insert more space.

 %

 \def\smallbreak{\ifnum\lastpenalty<10000\par\ifdim\lastskip<\smallskipamount

   \removelastskip\penalty-50\smallskip\fi\fi}

 \def\medbreak{\ifnum\lastpenalty<10000\par\ifdim\lastskip<\medskipamount

   \removelastskip\penalty-100\medskip\fi\fi}

 \def\bigbreak{\ifnum\lastpenalty<10000\par\ifdim\lastskip<\bigskipamount

   \removelastskip\penalty-200\bigskip\fi\fi}

 % For @cropmarks command.

 % Do @cropmarks to get crop marks.

 %

 \newif\ifcropmarks

 \let\cropmarks = \cropmarkstrue

 %

 % Dimensions to add cropmarks at corners.

 % Added by P. A. MacKay, 12 Nov. 1986

 %

 \newdimen\outerhsize \newdimen\outervsize % set by the paper size routines

 \newdimen\cornerlong  \cornerlong=1pc

 \newdimen\cornerthick \cornerthick=.3pt

 \newdimen\topandbottommargin \topandbottommargin=.75in

 % Main output routine.

 \chardef\PAGE = 255

 \output = {\onepageout{\pagecontents\PAGE}}

 \newbox\headlinebox

 \newbox\footlinebox

 % \onepageout takes a vbox as an argument.  Note that \pagecontents

 % does insertions, but you have to call it yourself.

 \def\onepageout#1{%

   \ifcropmarks \hoffset=0pt \else \hoffset=\normaloffset \fi

   %

   \ifodd\pageno  \advance\hoffset by \bindingoffset

   \else \advance\hoffset by -\bindingoffset\fi

   %

   % Do this outside of the \shipout so @code etc. will be expanded in

   % the headline as they should be, not taken literally (outputting ''code).

   \setbox\headlinebox = \vbox{\let\hsize=\pagewidth \makeheadline}%

   \setbox\footlinebox = \vbox{\let\hsize=\pagewidth \makefootline}%

   %

   {%

     % Have to do this stuff outside the \shipout because we want it to

     % take effect in \write's, yet the group defined by the \vbox ends

     % before the \shipout runs.

     %

     \escapechar = `\\     % use backslash in output files.

     \indexdummies         % don't expand commands in the output.

     \normalturnoffactive  % \ in index entries must not stay \, e.g., if

                    % the page break happens to be in the middle of an example.

     \shipout\vbox{%

       % Do this early so pdf references go to the beginning of the page.

       \ifpdfmakepagedest \pdfmkdest{\the\pageno} \fi

       %

       \ifcropmarks \vbox to \outervsize\bgroup

         \hsize = \outerhsize

         \vskip-\topandbottommargin

         \vtop to0pt{%

           \line{\ewtop\hfil\ewtop}%

           \nointerlineskip

           \line{%

             \vbox{\moveleft\cornerthick\nstop}%

             \hfill

             \vbox{\moveright\cornerthick\nstop}%

           }%

           \vss}%

         \vskip\topandbottommargin

         \line\bgroup

           \hfil % center the page within the outer (page) hsize.

           \ifodd\pageno\hskip\bindingoffset\fi

           \vbox\bgroup

       \fi

       %

       \unvbox\headlinebox

       \pagebody{#1}%

       \ifdim\ht\footlinebox > 0pt

         % Only leave this space if the footline is nonempty.

         % (We lessened \vsize for it in \oddfootingxxx.)

         % The \baselineskip=24pt in plain's \makefootline has no effect.

         \vskip 2\baselineskip

         \unvbox\footlinebox

       \fi

       %

       \ifcropmarks

           \egroup % end of \vbox\bgroup

         \hfil\egroup % end of (centering) \line\bgroup

         \vskip\topandbottommargin plus1fill minus1fill

         \boxmaxdepth = \cornerthick

         \vbox to0pt{\vss

           \line{%

             \vbox{\moveleft\cornerthick\nsbot}%

             \hfill

             \vbox{\moveright\cornerthick\nsbot}%

           }%

           \nointerlineskip

           \line{\ewbot\hfil\ewbot}%

         }%

       \egroup % \vbox from first cropmarks clause

       \fi

     }% end of \shipout\vbox

   }% end of group with \normalturnoffactive

   \advancepageno

   \ifnum\outputpenalty>-20000 \else\dosupereject\fi

 }

 \newinsert\margin \dimen\margin=\maxdimen

 \def\pagebody#1{\vbox to\pageheight{\boxmaxdepth=\maxdepth #1}}

 {\catcode`\@ =11

 \gdef\pagecontents#1{\ifvoid\topins\else\unvbox\topins\fi

 % marginal hacks, juha@viisa.uucp (Juha Takala)

 \ifvoid\margin\else % marginal info is present

   \rlap{\kern\hsize\vbox to\z@{\kern1pt\box\margin \vss}}\fi

 \dimen@=\dp#1 \unvbox#1

 \ifvoid\footins\else\vskip\skip\footins\footnoterule \unvbox\footins\fi

 \ifr@ggedbottom \kern-\dimen@ \vfil \fi}

 }

 % Here are the rules for the cropmarks.  Note that they are

 % offset so that the space between them is truly \outerhsize or \outervsize

 % (P. A. MacKay, 12 November, 1986)

 %

 \def\ewtop{\vrule height\cornerthick depth0pt width\cornerlong}

 \def\nstop{\vbox

   {\hrule height\cornerthick depth\cornerlong width\cornerthick}}

 \def\ewbot{\vrule height0pt depth\cornerthick width\cornerlong}

 \def\nsbot{\vbox

   {\hrule height\cornerlong depth\cornerthick width\cornerthick}}

 % Parse an argument, then pass it to #1.  The argument is the rest of

 % the input line (except we remove a trailing comment).  #1 should be a

 % macro which expects an ordinary undelimited TeX argument.

 %

 \def\parsearg#1{%

   \let\next = #1%

   \begingroup

     \obeylines

     \futurelet\temp\parseargx

 }

 % If the next token is an obeyed space (from an @example environment or

 % the like), remove it and recurse.  Otherwise, we're done.

 \def\parseargx{%

   % \obeyedspace is defined far below, after the definition of \sepspaces.

   \ifx\obeyedspace\temp

     \expandafter\parseargdiscardspace

   \else

     \expandafter\parseargline

   \fi

 }

 % Remove a single space (as the delimiter token to the macro call).

 {\obeyspaces %

  \gdef\parseargdiscardspace {\futurelet\temp\parseargx}}

 {\obeylines %

   \gdef\parseargline#1^^M{%

     \endgroup % End of the group started in \parsearg.

     %

     % First remove any @c comment, then any @comment.

     % Result of each macro is put in \toks0.

     \argremovec #1\c\relax %

     \expandafter\argremovecomment \the\toks0 \comment\relax %

     %

     % Call the caller's macro, saved as \next in \parsearg.

     \expandafter\next\expandafter{\the\toks0}%

   }%

 }

 % Since all \c{,omment} does is throw away the argument, we can let TeX

 % do that for us.  The \relax here is matched by the \relax in the call

 % in \parseargline; it could be more or less anything, its purpose is

 % just to delimit the argument to the \c.

 \def\argremovec#1\c#2\relax{\toks0 = {#1}}

 \def\argremovecomment#1\comment#2\relax{\toks0 = {#1}}

 % \argremovec{,omment} might leave us with trailing spaces, though; e.g.,

 %    @end itemize  @c foo

 % will have two active spaces as part of the argument with the

 % `itemize'.  Here we remove all active spaces from #1, and assign the

 % result to \toks0.

 %

 % This loses if there are any *other* active characters besides spaces

 % in the argument -- _ ^ +, for example -- since they get expanded.

 % Fortunately, Texinfo does not define any such commands.  (If it ever

 % does, the catcode of the characters in questionwill have to be changed

 % here.)  But this means we cannot call \removeactivespaces as part of

 % \argremovec{,omment}, since @c uses \parsearg, and thus the argument

 % that \parsearg gets might well have any character at all in it.

 %

 \def\removeactivespaces#1{%

   \begingroup

     \ignoreactivespaces

     \edef\temp{#1}%

     \global\toks0 = \expandafter{\temp}%

   \endgroup

 }

 % Change the active space to expand to nothing.

 %

 \begingroup

   \obeyspaces

   \gdef\ignoreactivespaces{\obeyspaces\let =\empty}

 \endgroup

 \def\flushcr{\ifx\par\lisppar \def\next##1{}\else \let\next=\relax \fi \next}

 %% These are used to keep @begin/@end levels from running away

 %% Call \inENV within environments (after a \begingroup)

 \newif\ifENV \ENVfalse \def\inENV{\ifENV\relax\else\ENVtrue\fi}

 \def\ENVcheck{%

 \ifENV\errmessage{Still within an environment; press RETURN to continue}

 \endgroup\fi} % This is not perfect, but it should reduce lossage

 % @begin foo  is the same as @foo, for now.

 \newhelp\EMsimple{Press RETURN to continue.}

 \outer\def\begin{\parsearg\beginxxx}

 \def\beginxxx #1{%

 \expandafter\ifx\csname #1\endcsname\relax

 {\errhelp=\EMsimple \errmessage{Undefined command @begin #1}}\else

 \csname #1\endcsname\fi}

 % @end foo executes the definition of \Efoo.

 %

 \def\end{\parsearg\endxxx}

 \def\endxxx #1{%

   \removeactivespaces{#1}%

   \edef\endthing{\the\toks0}%

   %

   \expandafter\ifx\csname E\endthing\endcsname\relax

     \expandafter\ifx\csname \endthing\endcsname\relax

       % There's no \foo, i.e., no ``environment'' foo.

       \errhelp = \EMsimple

       \errmessage{Undefined command `@end \endthing'}%

     \else

       \unmatchedenderror\endthing

     \fi

   \else

     % Everything's ok; the right environment has been started.

     \csname E\endthing\endcsname

   \fi

 }

 % There is an environment #1, but it hasn't been started.  Give an error.

 %

 \def\unmatchedenderror#1{%

   \errhelp = \EMsimple

   \errmessage{This `@end #1' doesn't have a matching `@#1'}%

 }

 % Define the control sequence \E#1 to give an unmatched @end error.

 %

 \def\defineunmatchedend#1{%

   \expandafter\def\csname E#1\endcsname{\unmatchedenderror{#1}}%

 }

 %% Simple single-character @ commands

 % @@ prints an @

 % Kludge this until the fonts are right (grr).

 \def\@{{\tt\char64}}

 % This is turned off because it was never documented

 % and you can use @w{...} around a quote to suppress ligatures.

 %% Define @` and @' to be the same as ` and '

 %% but suppressing ligatures.

 %\def\`{{`}}

 %\def\'{{'}}

 % Used to generate quoted braces.

 \def\mylbrace {{\tt\char123}}

 \def\myrbrace {{\tt\char125}}

 \let\{=\mylbrace

 \let\}=\myrbrace

 \begingroup

   % Definitions to produce \{ and \} commands for indices,

   % and @{ and @} for the aux file.

   \catcode`\{ = \other \catcode`\} = \other

   \catcode`\[ = 1 \catcode`\] = 2

   \catcode`\! = 0 \catcode`\\ = \other

   !gdef!lbracecmd[\{]%

   !gdef!rbracecmd[\}]%

   !gdef!lbraceatcmd[@{]%

   !gdef!rbraceatcmd[@}]%

 !endgroup

 % Accents: @, @dotaccent @ringaccent @ubaraccent @udotaccent

 % Others are defined by plain TeX: @` @' @" @^ @~ @= @u @v @H.

 \let\, = \c

 \let\dotaccent = \.

 \def\ringaccent#1{{\accent23 #1}}

 \let\tieaccent = \t

 \let\ubaraccent = \b

 \let\udotaccent = \d

 % Other special characters: @questiondown @exclamdown

 % Plain TeX defines: @AA @AE @O @OE @L (plus lowercase versions) @ss.

 \def\questiondown{?`}

 \def\exclamdown{!`}

 % Dotless i and dotless j, used for accents.

 \def\imacro{i}

 \def\jmacro{j}

 \def\dotless#1{%

   \def\temp{#1}%

   \ifx\temp\imacro \ptexi

   \else\ifx\temp\jmacro \j

   \else \errmessage{@dotless can be used only with i or j}%

   \fi\fi

 }

 % Be sure we're in horizontal mode when doing a tie, since we make space

 % equivalent to this in @example-like environments. Otherwise, a space

 % at the beginning of a line will start with \penalty -- and

 % since \penalty is valid in vertical mode, we'd end up putting the

 % penalty on the vertical list instead of in the new paragraph.

 {\catcode`@ = 11

  % Avoid using \@M directly, because that causes trouble

  % if the definition is written into an index file.

  \global\let\tiepenalty = \@M

  \gdef\tie{\leavevmode\penalty\tiepenalty\ }

 }

 % @: forces normal size whitespace following.

 \def\:{\spacefactor=1000 }

 % @* forces a line break.

 \def\*{\hfil\break\hbox{}\ignorespaces}

 % @/ allows a line break.

 \let\/=\allowbreak

 % @. is an end-of-sentence period.

 \def\.{.\spacefactor=3000 }

 % @! is an end-of-sentence bang.

 \def\!{!\spacefactor=3000 }

 % @? is an end-of-sentence query.

 \def\?{?\spacefactor=3000 }

 % @w prevents a word break.  Without the \leavevmode, @w at the

 % beginning of a paragraph, when TeX is still in vertical mode, would

 % produce a whole line of output instead of starting the paragraph.

 \def\w#1{\leavevmode\hbox{#1}}

 % @group ... @end group forces ... to be all on one page, by enclosing

 % it in a TeX vbox.  We use \vtop instead of \vbox to construct the box

 % to keep its height that of a normal line.  According to the rules for

 % \topskip (p.114 of the TeXbook), the glue inserted is

 % max (\topskip - \ht (first item), 0).  If that height is large,

 % therefore, no glue is inserted, and the space between the headline and

 % the text is small, which looks bad.

 %

 % Another complication is that the group might be very large.  This can

 % cause the glue on the previous page to be unduly stretched, because it

 % does not have much material.  In this case, it's better to add an

 % explicit \vfill so that the extra space is at the bottom.  The

 % threshold for doing this is if the group is more than \vfilllimit

 % percent of a page (\vfilllimit can be changed inside of @tex).

 %

 \newbox\groupbox

 \def\vfilllimit{0.7}

 %

 \def\group{\begingroup

   \ifnum\catcode13=\active \else

     \errhelp = \groupinvalidhelp

     \errmessage{@group invalid in context where filling is enabled}%

   \fi

   %

   % The \vtop we start below produces a box with normal height and large

   % depth; thus, TeX puts \baselineskip glue before it, and (when the

   % next line of text is done) \lineskip glue after it.  (See p.82 of

   % the TeXbook.)  Thus, space below is not quite equal to space

   % above.  But it's pretty close.

   \def\Egroup{%

     \egroup           % End the \vtop.

     % \dimen0 is the vertical size of the group's box.

     \dimen0 = \ht\groupbox  \advance\dimen0 by \dp\groupbox

     % \dimen2 is how much space is left on the page (more or less).

     \dimen2 = \pageheight   \advance\dimen2 by -\pagetotal

     % if the group doesn't fit on the current page, and it's a big big

     % group, force a page break.

     \ifdim \dimen0 > \dimen2

       \ifdim \pagetotal < \vfilllimit\pageheight

         \page

       \fi

     \fi

     \copy\groupbox

     \endgroup         % End the \group.

   }%

   %

   \setbox\groupbox = \vtop\bgroup

     % We have to put a strut on the last line in case the @group is in

     % the midst of an example, rather than completely enclosing it.

     % Otherwise, the interline space between the last line of the group

     % and the first line afterwards is too small.  But we can't put the

     % strut in \Egroup, since there it would be on a line by itself.

     % Hence this just inserts a strut at the beginning of each line.

     \everypar = {\strut}%

     %

     % Since we have a strut on every line, we don't need any of TeX's

     % normal interline spacing.

     \offinterlineskip

     %

     % OK, but now we have to do something about blank

     % lines in the input in @example-like environments, which normally

     % just turn into \lisppar, which will insert no space now that we've

     % turned off the interline space.  Simplest is to make them be an

     % empty paragraph.

     \ifx\par\lisppar

       \edef\par{\leavevmode \par}%

       %

       % Reset ^^M's definition to new definition of \par.

       \obeylines

     \fi

     %

     % Do @comment since we are called inside an environment such as

     % @example, where each end-of-line in the input causes an

     % end-of-line in the output.  We don't want the end-of-line after

     % the `@group' to put extra space in the output.  Since @group

     % should appear on a line by itself (according to the Texinfo

     % manual), we don't worry about eating any user text.

     \comment

 }

 %

 % TeX puts in an \escapechar (i.e., `@') at the beginning of the help

 % message, so this ends up printing `@group can only ...'.

 %

 \newhelp\groupinvalidhelp{%

 group can only be used in environments such as @example,^^J%

 where each line of input produces a line of output.}

 % @need space-in-mils

 % forces a page break if there is not space-in-mils remaining.

 \newdimen\mil  \mil=0.001in

 \def\need{\parsearg\needx}

 % Old definition--didn't work.

 %\def\needx #1{\par %

 %% This method tries to make TeX break the page naturally

 %% if the depth of the box does not fit.

 %{\baselineskip=0pt%

 %\vtop to #1\mil{\vfil}\kern -#1\mil\nobreak

 %\prevdepth=-1000pt

 %}}

 \def\needx#1{%

   % Ensure vertical mode, so we don't make a big box in the middle of a

   % paragraph.

   \par

   %

   % If the @need value is less than one line space, it's useless.

   \dimen0 = #1\mil

   \dimen2 = \ht\strutbox

   \advance\dimen2 by \dp\strutbox

   \ifdim\dimen0 > \dimen2

     %

     % Do a \strut just to make the height of this box be normal, so the

     % normal leading is inserted relative to the preceding line.

     % And a page break here is fine.

     \vtop to #1\mil{\strut\vfil}%

     %

     % TeX does not even consider page breaks if a penalty added to the

     % main vertical list is 10000 or more.  But in order to see if the

     % empty box we just added fits on the page, we must make it consider

     % page breaks.  On the other hand, we don't want to actually break the

     % page after the empty box.  So we use a penalty of 9999.

     %

     % There is an extremely small chance that TeX will actually break the

     % page at this \penalty, if there are no other feasible breakpoints in

     % sight.  (If the user is using lots of big @group commands, which

     % almost-but-not-quite fill up a page, TeX will have a hard time doing

     % good page breaking, for example.)  However, I could not construct an

     % example where a page broke at this \penalty; if it happens in a real

     % document, then we can reconsider our strategy.

     \penalty9999

     %

     % Back up by the size of the box, whether we did a page break or not.

     \kern -#1\mil

     %

     % Do not allow a page break right after this kern.

     \nobreak

   \fi

 }

 % @br   forces paragraph break

 \let\br = \par

 % @dots{} output an ellipsis using the current font.

 % We do .5em per period so that it has the same spacing in a typewriter

 % font as three actual period characters.

 %

 \def\dots{%

   \leavevmode

   \hbox to 1.5em{%

     \hskip 0pt plus 0.25fil minus 0.25fil

     .\hss.\hss.%

     \hskip 0pt plus 0.5fil minus 0.5fil

   }%

 }

 % @enddots{} is an end-of-sentence ellipsis.

 %

 \def\enddots{%

   \leavevmode

   \hbox to 2em{%

     \hskip 0pt plus 0.25fil minus 0.25fil

     .\hss.\hss.\hss.%

     \hskip 0pt plus 0.5fil minus 0.5fil

   }%

   \spacefactor=3000

 }

 % @page forces the start of a new page.

 %

 \def\page{\par\vfill\supereject}

 % @exdent text....

 % outputs text on separate line in roman font, starting at standard page margin

 % This records the amount of indent in the innermost environment.

 % That's how much \exdent should take out.

 \newskip\exdentamount

 % This defn is used inside fill environments such as @defun.

 \def\exdent{\parsearg\exdentyyy}

 \def\exdentyyy #1{{\hfil\break\hbox{\kern -\exdentamount{\rm#1}}\hfil\break}}

 % This defn is used inside nofill environments such as @example.

 \def\nofillexdent{\parsearg\nofillexdentyyy}

 \def\nofillexdentyyy #1{{\advance \leftskip by -\exdentamount

 \leftline{\hskip\leftskip{\rm#1}}}}

 % @inmargin{WHICH}{TEXT} puts TEXT in the WHICH margin next to the current

 % paragraph.  For more general purposes, use the \margin insertion

 % class.  WHICH is `l' or `r'.

 %

 \newskip\inmarginspacing \inmarginspacing=1cm

 \def\strutdepth{\dp\strutbox}

 %

 \def\doinmargin#1#2{\strut\vadjust{%

   \nobreak

   \kern-\strutdepth

   \vtop to \strutdepth{%

     \baselineskip=\strutdepth

     \vss

     % if you have multiple lines of stuff to put here, you'll need to

     % make the vbox yourself of the appropriate size.

     \ifx#1l%

       \llap{\ignorespaces #2\hskip\inmarginspacing}%

     \else

       \rlap{\hskip\hsize \hskip\inmarginspacing \ignorespaces #2}%

     \fi

     \null

   }%

 }}

 \def\inleftmargin{\doinmargin l}

 \def\inrightmargin{\doinmargin r}

 %

 % @inmargin{TEXT [, RIGHT-TEXT]}

 % (if RIGHT-TEXT is given, use TEXT for left page, RIGHT-TEXT for right;

 % else use TEXT for both).

 %

 \def\inmargin#1{\parseinmargin #1,,\finish}

 \def\parseinmargin#1,#2,#3\finish{% not perfect, but better than nothing.

   \setbox0 = \hbox{\ignorespaces #2}%

   \ifdim\wd0 > 0pt

     \def\lefttext{#1}%  have both texts

     \def\righttext{#2}%

   \else

     \def\lefttext{#1}%  have only one text

     \def\righttext{#1}%

   \fi

   %

   \ifodd\pageno

     \def\temp{\inrightmargin\righttext}% odd page -> outside is right margin

   \else

     \def\temp{\inleftmargin\lefttext}%

   \fi

   \temp

 }

 % @include file    insert text of that file as input.

 % Allow normal characters that  we make active in the argument (a file name).

 \def\include{\begingroup

   \catcode`\\=\other

   \catcode`~=\other

   \catcode`^=\other

   \catcode`_=\other

   \catcode`|=\other

   \catcode`<=\other

   \catcode`>=\other

   \catcode`+=\other

   \parsearg\includezzz}

 % Restore active chars for included file.

 \def\includezzz#1{\endgroup\begingroup

   % Read the included file in a group so nested @include's work.

   \def\thisfile{#1}%

   \let\value=\expandablevalue

   \input\thisfile

 \endgroup}

 \def\thisfile{}

 % @center line

 % outputs that line, centered.

 %

 \def\center{\parsearg\docenter}

 \def\docenter#1{{%

   \ifhmode \hfil\break \fi

   \advance\hsize by -\leftskip

   \advance\hsize by -\rightskip

   \line{\hfil \ignorespaces#1\unskip \hfil}%

   \ifhmode \break \fi

 }}

 % @sp n   outputs n lines of vertical space

 \def\sp{\parsearg\spxxx}

 \def\spxxx #1{\vskip #1\baselineskip}

 % @comment ...line which is ignored...

 % @c is the same as @comment

 % @ignore ... @end ignore  is another way to write a comment

 \def\comment{\begingroup \catcode`\^^M=\other%

 \catcode`\@=\other \catcode`\{=\other \catcode`\}=\other%

 \commentxxx}

 {\catcode`\^^M=\other \gdef\commentxxx#1^^M{\endgroup}}

 \let\c=\comment

 % @paragraphindent NCHARS

 % We'll use ems for NCHARS, close enough.

 % NCHARS can also be the word `asis' or `none'.

 % We cannot feasibly implement @paragraphindent asis, though.

 %

 \def\asisword{asis} % no translation, these are keywords

 \def\noneword{none}

 %

 \def\paragraphindent{\parsearg\doparagraphindent}

 \def\doparagraphindent#1{%

   \def\temp{#1}%

   \ifx\temp\asisword

   \else

     \ifx\temp\noneword

       \defaultparindent = 0pt

     \else

       \defaultparindent = #1em

     \fi

   \fi

   \parindent = \defaultparindent

 }

 % @exampleindent NCHARS

 % We'll use ems for NCHARS like @paragraphindent.

 % It seems @exampleindent asis isn't necessary, but

 % I preserve it to make it similar to @paragraphindent.

 \def\exampleindent{\parsearg\doexampleindent}

 \def\doexampleindent#1{%

   \def\temp{#1}%

   \ifx\temp\asisword

   \else

     \ifx\temp\noneword

       \lispnarrowing = 0pt

     \else

       \lispnarrowing = #1em

     \fi

   \fi

 }

 % @firstparagraphindent WORD

 % If WORD is `none', then suppress indentation of the first paragraph

 % after a section heading.  If WORD is `insert', then do indent at such

 % paragraphs.

 %

 % The paragraph indentation is suppressed or not by calling

 % \suppressfirstparagraphindent, which the sectioning commands do.

 % We switch the definition of this back and forth according to WORD.

 % By default, we suppress indentation.

 %

 \def\suppressfirstparagraphindent{\dosuppressfirstparagraphindent}

 \newdimen\currentparindent

 %

 \def\insertword{insert}

 %

 \def\firstparagraphindent{\parsearg\dofirstparagraphindent}

 \def\dofirstparagraphindent#1{%

   \def\temp{#1}%

   \ifx\temp\noneword

     \let\suppressfirstparagraphindent = \dosuppressfirstparagraphindent

   \else\ifx\temp\insertword

     \let\suppressfirstparagraphindent = \relax

   \else

     \errhelp = \EMsimple

     \errmessage{Unknown @firstparagraphindent option `\temp'}%

   \fi\fi

 }

 % Here is how we actually suppress indentation.  Redefine \everypar to

 % \kern backwards by \parindent, and then reset itself to empty.

 %

 % We also make \indent itself not actually do anything until the next

 % paragraph.

 %

 \gdef\dosuppressfirstparagraphindent{%

   \gdef\indent{%

     \global\let\indent=\ptexindent

     \global\everypar = {}%

   }%

   \global\everypar = {%

     \kern-\parindent

     \global\let\indent=\ptexindent

     \global\everypar = {}%

   }%

 }%

 % @asis just yields its argument.  Used with @table, for example.

 %

 \def\asis#1{#1}

 % @math outputs its argument in math mode.

 % We don't use $'s directly in the definition of \math because we need

 % to set catcodes according to plain TeX first, to allow for subscripts,

 % superscripts, special math chars, etc.

 %

 \let\implicitmath = $%$ font-lock fix

 %

 % One complication: _ usually means subscripts, but it could also mean

 % an actual _ character, as in @math{@var{some_variable} + 1}.  So make

 % _ within @math be active (mathcode "8000), and distinguish by seeing

 % if the current family is \slfam, which is what @var uses.

 %

 {\catcode\underChar = \active

 \gdef\mathunderscore{%

   \catcode\underChar=\active

   \def_{\ifnum\fam=\slfam \_\else\sb\fi}%

 }}

 %

 % Another complication: we want \\ (and @\) to output a \ character.

 % FYI, plain.tex uses \\ as a temporary control sequence (why?), but

 % this is not advertised and we don't care.  Texinfo does not

 % otherwise define @\.

 %

 % The \mathchar is class=0=ordinary, family=7=ttfam, position=5C=\.

 \def\mathbackslash{\ifnum\fam=\ttfam \mathchar"075C \else\backslash \fi}

 %

 \def\math{%

   \tex

   \mathcode`\_="8000 \mathunderscore

   \let\\ = \mathbackslash

   \mathactive

   \implicitmath\finishmath}

 \def\finishmath#1{#1\implicitmath\Etex}

 % Some active characters (such as <) are spaced differently in math.

 % We have to reset their definitions in case the @math was an

 % argument to a command which set the catcodes (such as @item or @section).

 %

 {

   \catcode`^ = \active

   \catcode`< = \active

   \catcode`> = \active

   \catcode`+ = \active

   \gdef\mathactive{%

     \let^ = \ptexhat

     \let< = \ptexless

     \let> = \ptexgtr

     \let+ = \ptexplus

   }

 }

 % @bullet and @minus need the same treatment as @math, just above.

 \def\bullet{\implicitmath\ptexbullet\implicitmath}

 \def\minus{\implicitmath-\implicitmath}

 % @refill is a no-op.

 \let\refill=\relax

 % If working on a large document in chapters, it is convenient to

 % be able to disable indexing, cross-referencing, and contents, for test runs.

 % This is done with @novalidate (before @setfilename).

 %

 \newif\iflinks \linkstrue % by default we want the aux files.

 \let\novalidate = \linksfalse

 % @setfilename is done at the beginning of every texinfo file.

 % So open here the files we need to have open while reading the input.

 % This makes it possible to make a .fmt file for texinfo.

 \def\setfilename{%

    \iflinks

      \readauxfile

    \fi % \openindices needs to do some work in any case.

    \openindices

    \fixbackslash  % Turn off hack to swallow `\input texinfo'.

    \global\let\setfilename=\comment % Ignore extra @setfilename cmds.

    %

    % If texinfo.cnf is present on the system, read it.

    % Useful for site-wide @afourpaper, etc.

    % Just to be on the safe side, close the input stream before the \input.

    \openin 1 texinfo.cnf

    \ifeof1 \let\temp=\relax \else \def\temp{\input texinfo.cnf }\fi

    \closein1

    \temp

    %

    \comment % Ignore the actual filename.

 }

 % Called from \setfilename.

 %

 \def\openindices{%

   \newindex{cp}%

   \newcodeindex{fn}%

   \newcodeindex{vr}%

   \newcodeindex{tp}%

   \newcodeindex{ky}%

   \newcodeindex{pg}%

 }

 % @bye.

 \outer\def\bye{\pagealignmacro\tracingstats=1\ptexend}

 \message{pdf,}

 % adobe `portable' document format

 \newcount\tempnum

 \newcount\lnkcount

 \newtoks\filename

 \newcount\filenamelength

 \newcount\pgn

 \newtoks\toksA

 \newtoks\toksB

 \newtoks\toksC

 \newtoks\toksD

 \newbox\boxA

 \newcount\countA

 \newif\ifpdf

 \newif\ifpdfmakepagedest

 \ifx\pdfoutput\undefined

   \pdffalse

   \let\pdfmkdest = \gobble

   \let\pdfurl = \gobble

   \let\endlink = \relax

   \let\linkcolor = \relax

   \let\pdfmakeoutlines = \relax

 \else

   \pdftrue

   \pdfoutput = 1

   \input pdfcolor

   \def\dopdfimage#1#2#3{%

     \def\imagewidth{#2}%

     \def\imageheight{#3}%

     % without \immediate, pdftex seg faults when the same image is

     % included twice.  (Version 3.14159-pre-1.0-unofficial-20010704.)

     \ifnum\pdftexversion < 14

       \immediate\pdfimage

     \else

       \immediate\pdfximage

     \fi

       \ifx\empty\imagewidth\else width \imagewidth \fi

       \ifx\empty\imageheight\else height \imageheight \fi

       \ifnum\pdftexversion<13

          #1.pdf%

        \else

          {#1.pdf}%

        \fi

     \ifnum\pdftexversion < 14 \else

       \pdfrefximage \pdflastximage

     \fi}

   \def\pdfmkdest#1{{\normalturnoffactive \pdfdest name{#1} xyz}}

   \def\pdfmkpgn#1{#1}

   \let\linkcolor = \Blue  % was Cyan, but that seems light?

   \def\endlink{\Black\pdfendlink}

   % Adding outlines to PDF; macros for calculating structure of outlines

   % come from Petr Olsak

   \def\expnumber#1{\expandafter\ifx\csname#1\endcsname\relax 0%

     \else \csname#1\endcsname \fi}

   \def\advancenumber#1{\tempnum=\expnumber{#1}\relax

     \advance\tempnum by1

     \expandafter\xdef\csname#1\endcsname{\the\tempnum}}

   \def\pdfmakeoutlines{{%

     \openin 1 \jobname.toc

     \ifeof 1\else\begingroup

       \closein 1

       % Thanh's hack / proper braces in bookmarks

       \edef\mylbrace{\iftrue \string{\else}\fi}\let\{=\mylbrace

       \edef\myrbrace{\iffalse{\else\string}\fi}\let\}=\myrbrace

       %

       \def\chapentry ##1##2##3{}

       \def\secentry ##1##2##3##4{\advancenumber{chap##2}}

       \def\subsecentry ##1##2##3##4##5{\advancenumber{sec##2.##3}}

       \def\subsubsecentry ##1##2##3##4##5##6{\advancenumber{subsec##2.##3.##4}}

       \let\appendixentry = \chapentry

       \let\unnumbchapentry = \chapentry

       \let\unnumbsecentry = \secentry

       \let\unnumbsubsecentry = \subsecentry

       \let\unnumbsubsubsecentry = \subsubsecentry

       \input \jobname.toc

       \def\chapentry ##1##2##3{%

         \pdfoutline goto name{\pdfmkpgn{##3}}count-\expnumber{chap##2}{##1}}

       \def\secentry ##1##2##3##4{%

         \pdfoutline goto name{\pdfmkpgn{##4}}count-\expnumber{sec##2.##3}{##1}}

       \def\subsecentry ##1##2##3##4##5{%

         \pdfoutline goto name{\pdfmkpgn{##5}}count-\expnumber{subsec##2.##3.##4}{##1}}

       \def\subsubsecentry ##1##2##3##4##5##6{%

         \pdfoutline goto name{\pdfmkpgn{##6}}{##1}}

       \let\appendixentry = \chapentry

       \let\unnumbchapentry = \chapentry

       \let\unnumbsecentry = \secentry

       \let\unnumbsubsecentry = \subsecentry

       \let\unnumbsubsubsecentry = \subsubsecentry

       %

       % Make special characters normal for writing to the pdf file.

       %

       \indexnofonts

       \let\tt=\relax

       \turnoffactive

       \input \jobname.toc