+% @url synonym for @uref, since that's how everyone uses it.
+%
+\let\url=\uref
+
+% rms does not like angle brackets --karl, 17may97.
+% So now @email is just like @uref, unless we are pdf.
+%
+%\def\email#1{\angleleft{\tt #1}\angleright}
+\ifpdf
+ \def\email#1{\doemail#1,,\finish}
+ \def\doemail#1,#2,#3\finish{\begingroup
+ \unsepspaces
+ \pdfurl{mailto:#1}%
+ \setbox0 = \hbox{\ignorespaces #2}%
+ \ifdim\wd0>0pt\unhbox0\else\code{#1}\fi
+ \endlink
+ \endgroup}
+\else
+ \let\email=\uref
+\fi
+
+% Typeset a dimension, e.g., `in' or `pt'. The only reason for the
+% argument is to make the input look right: @dmn{pt} instead of @dmn{}pt.
+%
+\def\dmn#1{\thinspace #1}
+
+% @l was never documented to mean ``switch to the Lisp font'',
+% and it is not used as such in any manual I can find. We need it for
+% Polish suppressed-l. --karl, 22sep96.
+%\def\l#1{{\li #1}\null}
+
+% @acronym for "FBI", "NATO", and the like.
+% We print this one point size smaller, since it's intended for
+% all-uppercase.
+%
+\def\acronym#1{\doacronym #1,,\finish}
+\def\doacronym#1,#2,#3\finish{%
+ {\selectfonts\lsize #1}%
+ \def\temp{#2}%
+ \ifx\temp\empty \else
+ \space ({\unsepspaces \ignorespaces \temp \unskip})%
+ \fi
+}
+
+% @abbr for "Comput. J." and the like.
+% No font change, but don't do end-of-sentence spacing.
+%
+\def\abbr#1{\doabbr #1,,\finish}
+\def\doabbr#1,#2,#3\finish{%
+ {\plainfrenchspacing #1}%
+ \def\temp{#2}%
+ \ifx\temp\empty \else
+ \space ({\unsepspaces \ignorespaces \temp \unskip})%
+ \fi
+}
+
+% @asis just yields its argument. Used with @table, for example.
+%
+\def\asis#1{#1}
+
+% @math outputs its argument in math mode.
+%
+% One complication: _ usually means subscripts, but it could also mean
+% an actual _ character, as in @math{@var{some_variable} + 1}. So make
+% _ active, and distinguish by seeing if the current family is \slfam,
+% which is what @var uses.
+{
+ \catcode`\_ = \active
+ \gdef\mathunderscore{%
+ \catcode`\_=\active
+ \def_{\ifnum\fam=\slfam \_\else\sb\fi}%
+ }
+}
+% Another complication: we want \\ (and @\) to output a math (or tt) \.
+% FYI, plain.tex uses \\ as a temporary control sequence (for no
+% particular reason), but this is not advertised and we don't care.
+%
+% The \mathchar is class=0=ordinary, family=7=ttfam, position=5C=\.
+\def\mathbackslash{\ifnum\fam=\ttfam \mathchar"075C \else\backslash \fi}
+%
+\def\math{%
+ \tex
+ \mathunderscore
+ \let\\ = \mathbackslash
+ \mathactive
+ % make the texinfo accent commands work in math mode
+ \let\"=\ddot
+ \let\'=\acute
+ \let\==\bar
+ \let\^=\hat
+ \let\`=\grave
+ \let\u=\breve
+ \let\v=\check
+ \let\~=\tilde
+ \let\dotaccent=\dot
+ $\finishmath
+}
+\def\finishmath#1{#1$\endgroup} % Close the group opened by \tex.
+
+% 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 sets the catcodes (such as @item or @section).
+%
+{
+ \catcode`^ = \active
+ \catcode`< = \active
+ \catcode`> = \active
+ \catcode`+ = \active
+ \catcode`' = \active
+ \gdef\mathactive{%
+ \let^ = \ptexhat
+ \let< = \ptexless
+ \let> = \ptexgtr
+ \let+ = \ptexplus
+ \let' = \ptexquoteright
+ }
+}
+
+
+\message{glyphs,}
+% and logos.
+
+% @@ prints an @.
+\def\@{\char64 }
+
+% Used to generate quoted braces. Unless we're in typewriter, use
+% \ecfont because the CM text fonts do not have braces, and we don't
+% want to switch into math.
+\def\mylbrace{{\ifmonospace\else\ecfont\fi \char123}}
+\def\myrbrace{{\ifmonospace\else\ecfont\fi \char125}}
+\let\{=\mylbrace
+\let\}=\myrbrace
+\begingroup
+ % Definitions to produce \{ and \} commands for indices,
+ % and @{ and @} for the aux/toc files.
+ \catcode`\{ = \other \catcode`\} = \other
+ \catcode`\[ = 1 \catcode`\] = 2
+ \catcode`\! = 0 \catcode`\\ = \other
+ !gdef!lbracecmd[\{]%
+ !gdef!rbracecmd[\}]%
+ !gdef!lbraceatcmd[@{]%
+ !gdef!rbraceatcmd[@}]%
+!endgroup
+
+% @comma{} to avoid , parsing problems.
+\let\comma = ,
+
+% Accents: @, @dotaccent @ringaccent @ubaraccent @udotaccent
+% Others are defined by plain TeX: @` @' @" @^ @~ @= @u @v @H.
+\let\, = \ptexc
+\let\dotaccent = \ptexdot
+\def\ringaccent#1{{\accent23 #1}}
+\let\tieaccent = \ptext
+\let\ubaraccent = \ptexb
+\let\udotaccent = \d