> > I have come across a very strage situation in which
> > the behaviour of groff seems to depend on:
> >
> > a. whether it happens in a diversion or not and
> > b. the presence of a comment.
>
> Multiline conditionals are a bit tricky.
> The following conditionals should work:
Forgot this type:
.if condition \{stuff
more stuff
even more stuff\}
which resembles your example, with the first "stuff"
being an *empty line* that has a comment.
See also the explanation here:
http://lists.gnu.org/archive/html/groff/2004-01/msg00106.html
(and the other messages of this thread).