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