No they aren't. 10000 can be a valid year according to ISO8601, but sorted as a string it would come before year 2000, which would obviously be incorrect. Her

No they aren't. 10000 can be a valid year according to ISO8601, but sorted as a string it would come before year 2000, which would obviously be incorrect. Here's from the ISO: > 3.5 Expansion By mutual agreement of the partners in information interchange, it is permitted to expand the component identifying the calendar year, which is otherwise limited to four digits. This enables reference to dates and times in calendar years outside the range supported by complete representations, i.e. before the start of the year [0000] or after the end of the year [9999].