I think the standard is something along the lines of:
if ($year + 50 < ($current_year - 2000)) { $year += 1900 } else { $year += 2000 }
Except that this will probably be wrong when used to convert birthdates of retirees (actual project I had to deal with, BTW). See:
http://www.dmi.uiuc.edu/y2k/window.htm
for a way to handle moving windows.
The two digit year format is so pernicious that it demands a warning in pretty much all cases, and an error in any situation where the data is important.
John
-- John Peacock Director of Information Research and Technology Rowman & Littlefield Publishing Group 4501 Forbes Boulevard Suite H Lanham, MD 20706 301-459-3366 x.5010 fax 301-429-5748