To do the leap year calculation correctly, you'll need a field coded like:
{QUOTE{SET Yr {DATE \@ YYYY}}{SET Mo {DATE \@ M}}{=({=G8}=28)*((MOD(Yr,4)=0)+(MOD(Yr,400)=0)-(MOD(Yr,100)=0))*(Mo=2)*29 \# 0;;}}
In the above, '*' functions as an AND condition and '+' functions as an OR condition.

To see how to do just about everything else you might want to do with dates in Word, check out my Microsoft Word Date Calculation Tutorial, at:
http://windowssecrets.com/forums/sho...ation-Tutorial
or
http://www.gmayor.com/downloads.htm#Third_party
Do read the document's introductory material.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]