Tadziu Hoffmann: The error must have been introduced between 1.19.2 and 1.19.3, and it's a bug in the mm macros, not in troff, as you can see by sourc- ing the 1.19.2 mm macros with troff 1.20.1 (and vice versa).
If you edit the current mm macros and move the addr...@hidden call in the definition of the paragraph macro outside the conditional (as in the 1.19.2 mm macros) (and additionally delete the devtag macro calls because the seem to introduce unwanted empty lines), I think you get the correct behavior. I have determined that this bug was introduced in the version 2.33 of m.tmac. The difference between 2.32 and 2.33 is very little -- just one line that moves the call to par[at]doit inside the condi- tion. The patch's description says it immplements the skipping of .P after .H. I suggest that this patch should be undone because it introduced the bug. Anton
