/sys/lib/tmac.an (troff -man) loads the LucidaSans fonts:
.fp 1 R LucidaSans
.fp 2 I LucidaSansI
.fp 3 B LucidaSansB
.fp 5 L LucidaCW

If you don't have those, some other font is substituted and that'll
make your output look ugly.

(/sys/lib/tmac.s (troff -ms) doesn't load fonts (defaults to Times roman)

	Sape