Re: texinfo.tex doesn't allow underscore in flag names for @ifset etc.

[W. L. Estes]

> I think it's very difficult to support underscores in this case.
> OTOH, some people object to introducing limitations into makeinfo just
> because TeX doesn't support that, since Texinfo documents might be
> written that are not intended to be processed by TeX.  For example,
> you could write a document that is only supposed to exist as an online
> version.

The texinfo manual states the following:

  Texinfo is a documentation system that uses a single source file to
produce both online information and printed output.

That's the first sentence from the Top node of the texinfo manual.

So, it's wrong  if the online processor and the hardcopy processor do
not accept the same language.