Omigod - a Real Y2K problem!
In the MM macro package - tmac.m the default date prints as
	January 12, 19100
when the .ND macro is omitted.
Obviously this is easily circumvented by using .ND but it's just
about the only Y2K problem I've come across in all of Linux.

This seems to fix it:

# diff tmac.mSAV tmac.m
2623,2624c2623,2624
< .ie \\n[yr]<50 .ds cov*new-date \\*[MO\\n[mo]] \\n[dy], 20\\n[yr]
< .el .ds cov*new-date \\*[MO\\n[mo]] \\n[dy], 19\\n[yr]
---
> .nr cov*year 1900+\n[yr]
> .ds cov*new-date \*[MO\n[mo]] \n[dy], \n[cov*year]


Someone with more competence than me ought to check this out.

Please don't "fix" this by dropping tmac.m as is presently being done.
(see my earlier Bugzilla #8362.)