You're right.. their line:

$SerialDate=$d+(153*$m-457)/5+365*$y+$y/4-$y/100+$y/400-306

does everything in one line that i do in several lines. However, you have to go through a bunch of math theorems to come up with that formula... (I know.. someone worked it out a long time ago. I saw something like that in the 3rd grade.).. Anyway it's just a good exercise to do it yourself! (and my code is smaller than with the functions from scriptlogic)

Brian