+% 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
+ \implicitmath\finishmath}