AARGH! I just "upgraded" from groff-1.11a-9 to groff-1.15-1.
To my horror the file /usr/lib/groff/tmac/tmac.m is gone.
I restored it for the nonce from the earlier package.
Believe it or not, some of us still use troff almost daily and
depend on it. Some of us old ex-Bell Labs folks just cannot function
without the good old MM macros of yore. Please restore tmac.m
to the groff collection.
Apparently everything works OK if the old file is simply added.
The file /usr/lib/groff/tmac/tmac.m was incorrectly installed as tmac.
Fixed (by renaming the file) in groff-1.15-7.