Hi Stefan - indeed, fractions a la \frac have never been supported in
Texinfo. Or display math, or all kinds of other things.
Env |- Exp1 : Type1 Env |- Exp2 : Type2
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Env |- Exp3 : Type3
I'm not sure what kind of input you are hoping for. But I fear that
this is a case where using @macro (or m4/other preprocessor macros,
except apparently nobody except me ever liked that idea) is the best
option. Yes, you'd have to write different macro bodies for TeX, HTML,
Info[, Docbook, XML].
There will surely be plenty of problems, but I can't think of any other
approach, unless Gavin feels like adding a new @frac{num,den} (or
whatever) command, and you want to use a brand-new command in your
source ...
As for the general concept of "typing rules", I don't understand. It's
not possible to document "X in LaTeX is equivalent to Y in Texinfo" for
the simple reason that only a tiny fraction ( :) of LaTeX is in Texinfo.
By design. And anyway the purpose of the Texinfo manual is to document
Texinfo, not LaTeX. But I know you already know all this, so I suppose
you must mean something else ...
Best,
Karl
