If civilization continues to the year 9999, is the idea to go to year 10.000, or...?
It seems like it'd get increasingly impractical as the years go on to hundreds of thousands and millions of years to write them out that way, but then...I guess technically one may already do this with the preceding years, so future's fair game for it?
I was looking at some old pictures of my family and some of them had dates like 921 for 1921 in them. I used to abbreviate 88 for 1988, but I’ve never seen people using 3 digits like that.
During y2k, a third digit was one of the compromises for languages like Perl. There were so many places that only displayed a two digit year but rolling over to 00 would have made it difficult to sort or do date math, or even to convert to a four digit year. So the year rolled over from 99 to 100, so dates with two digit years could be sorted correctly. If you were only displaying two digits, it probably correctly displayed as 00. If you wanted to convert to four digit years,just add 1900