Re: groff 1.19.1 complains when formatting its own man pages

[Paul Eggert]

Here's another idea: have compatibility mode apply more "statically"
than "dynamically".  That is, if \n[.C] is 1, then ".de XX" should
should cause XX to be executed in compatibility mode, restoring the
old compatibility mode when it exits.  (This is sort of the inverse of
".de1 XX".)  Similarly for ".ds".

This approach seems simpler, more general, and more likely to "do the
right thing" in other cases as well.