+
+\message{markup,}
+
+% Check if we are currently using a typewriter font. Since all the
+% Computer Modern typewriter fonts have zero interword stretch (and
+% shrink), and it is reasonable to expect all typewriter fonts to have
+% this property, we can check that font parameter.
+%
+\def\ifmonospace{\ifdim\fontdimen3\font=0pt }
+
+% Markup style infrastructure. \defmarkupstylesetup\INITMACRO will
+% define and register \INITMACRO to be called on markup style changes.
+% \INITMACRO can check \currentmarkupstyle for the innermost
+% style and the set of \ifmarkupSTYLE switches for all styles
+% currently in effect.
+\newif\ifmarkupvar
+\newif\ifmarkupsamp
+\newif\ifmarkupkey
+%\newif\ifmarkupfile % @file == @samp.
+%\newif\ifmarkupoption % @option == @samp.
+\newif\ifmarkupcode
+\newif\ifmarkupkbd
+%\newif\ifmarkupenv % @env == @code.
+%\newif\ifmarkupcommand % @command == @code.
+\newif\ifmarkuptex % @tex (and part of @math, for now).
+\newif\ifmarkupexample
+\newif\ifmarkupverb
+\newif\ifmarkupverbatim
+
+\let\currentmarkupstyle\empty
+
+\def\setupmarkupstyle#1{%
+ \csname markup#1true\endcsname
+ \def\currentmarkupstyle{#1}%
+ \markupstylesetup
+}
+
+\let\markupstylesetup\empty
+
+\def\defmarkupstylesetup#1{%
+ \expandafter\def\expandafter\markupstylesetup
+ \expandafter{\markupstylesetup #1}%
+ \def#1%
+}
+
+% Markup style setup for left and right quotes.
+\defmarkupstylesetup\markupsetuplq{%
+ \expandafter\let\expandafter \temp \csname markupsetuplq\currentmarkupstyle\endcsname
+ \ifx\temp\relax \markupsetuplqdefault \else \temp \fi
+}
+
+\defmarkupstylesetup\markupsetuprq{%
+ \expandafter\let\expandafter \temp \csname markupsetuprq\currentmarkupstyle\endcsname
+ \ifx\temp\relax \markupsetuprqdefault \else \temp \fi
+}
+
+{
+\catcode`\'=\active
+\catcode`\`=\active
+
+\gdef\markupsetuplqdefault{\let`\lq}
+\gdef\markupsetuprqdefault{\let'\rq}
+
+\gdef\markupsetcodequoteleft{\let`\codequoteleft}
+\gdef\markupsetcodequoteright{\let'\codequoteright}
+
+\gdef\markupsetnoligaturesquoteleft{\let`\noligaturesquoteleft}
+}
+
+\let\markupsetuplqcode \markupsetcodequoteleft
+\let\markupsetuprqcode \markupsetcodequoteright
+\let\markupsetuplqexample \markupsetcodequoteleft
+\let\markupsetuprqexample \markupsetcodequoteright
+\let\markupsetuplqverb \markupsetcodequoteleft
+\let\markupsetuprqverb \markupsetcodequoteright
+\let\markupsetuplqverbatim \markupsetcodequoteleft
+\let\markupsetuprqverbatim \markupsetcodequoteright
+
+\let\markupsetuplqsamp \markupsetnoligaturesquoteleft
+\let\markupsetuplqkbd \markupsetnoligaturesquoteleft
+
+% Allow an option to not replace quotes with a regular directed right
+% quote/apostrophe (char 0x27), but instead use the undirected quote
+% from cmtt (char 0x0d). The undirected quote is ugly, so don't make it
+% the default, but it works for pasting with more pdf viewers (at least
+% evince), the lilypond developers report. xpdf does work with the
+% regular 0x27.
+%
+\def\codequoteright{%
+ \expandafter\ifx\csname SETtxicodequoteundirected\endcsname\relax
+ \expandafter\ifx\csname SETcodequoteundirected\endcsname\relax
+ '%
+ \else \char'15 \fi
+ \else \char'15 \fi
+}
+%
+% and a similar option for the left quote char vs. a grave accent.
+% Modern fonts display ASCII 0x60 as a grave accent, so some people like
+% the code environments to do likewise.
+%
+\def\codequoteleft{%
+ \expandafter\ifx\csname SETtxicodequotebacktick\endcsname\relax
+ \expandafter\ifx\csname SETcodequotebacktick\endcsname\relax
+ % [Knuth] pp. 380,381,391
+ % \relax disables Spanish ligatures ?` and !` of \tt font.
+ \relax`%
+ \else \char'22 \fi
+ \else \char'22 \fi
+}
+
+% [Knuth] pp. 380,381,391, disable Spanish ligatures ?` and !` of \tt font.
+\def\noligaturesquoteleft{\relax\lq}