I have a manpage.8.in type file with lines like: .br .B admindo .B create .BR \-s [erver] .I name .BR \-p [artition] .I name .BR \-n [ame] I want to wrap that section such that if HAVE_MKAFSVOL was defined via the configure script (via AC_DEFINE) then that section gets included in the resulting manpage.8 file, but doesn't if it wasn't. How is that done?