ncal -p prints a table with the transition date from Julian to Gregorian for some, but by no means all, "countries". It also includes an entry for the country "Latin", with a transition date 9999-5-31. The commit log for revision r45064 clarifies that this is because 9999-12-12 is out of range. It's not clear why this entry was ever added. Many real countries (Armenia and Azerbaijan, for example) aren't in this list. Arguably the entire functionality should be removed; it's not needed for anything else in the program, and more up-to-date information is now readily available on the web (https://en.wikipedia.org/wiki/List_of_adoption_dates_of_the_Gregorian_calendar_per_country for example). I would suggest at least removing the entry for "Latin". Reported by: Hamid Ali.
A commit references this bug: Author: grog Date: Sun Mar 29 04:18:28 UTC 2020 New revision: 359419 URL: https://svnweb.freebsd.org/changeset/base/359419 Log: Remove spurious transition from Julian to Gregorian for country "Latin". Arguably the entire -p option should be removed. It shows only a few countries, and it doesn't have any relationship with the rest of the program. PR: 244801 Submitted by: grog@ Reported by: Hamid Ali Changes: head/usr.bin/ncal/ncal.c
"Latin" removed from the list of transitions. This is a conservative approach; the whole functionality should really be removed.