Given that the source: https://minnie.tuhs.org//cgi-bin/utree.pl?file=V6/usr/source/s1/cal.c has been in C since at least V6, I'd be rather surprised if on other machines it did anything other than what those of us who were paying attention read in the documentation: https://minnie.tuhs.org//cgi-bin/utree.pl?file=V6/usr/man/man6/cal.6 back then: "Try September 1752." Get off my lawn. Noel PS: Said documentation already notes that it won't work in most counries: "The calendar produced is that for England and her colonies." For more fun with calendates, check out the Japanese Lunar-Solar Calendar: http://www.chiappa.net/~jnc/prints/calendar.html