@ifhtml
and @end ifhtml
@ifhtml blocks are similar to @ifinfo and @iftex blocks. Lines between @ifhtml and @end ifhtml get processed when generating the hypertext manual but get ignored when generating the printed manual.
texinfo.tex (in /usr/local/lib/tex/macros on my machine) needs to be modified in order to use @ifhtml. I inserted
\def\ifhtml{\doignore{ifhtml}}
after the \def\ifinfo{\doignore{ifinfo}}
line (line
596 ???).
In most cases, it is better to use @ifinfo than @ifhtml.