The date on my Venix system doesn't grok 20xx at all. I had to hack date.c from v7 to make it work. So at some point you had to hack things in to make 20xx work, no?
Heh, my V6 machine thinks (via 'date') that today is _Monday_, December
12th. Oddly enough, 'cal 17 2017' on it produces the right thing. Guess the
date code is probably missing the '400 year' exception.
Noel