>George
>
>

lIsLeapYr = (nyear % 4 = 0) AND (nyear % 400 = 0)

>
>it works for 2000, but not for 2004. why ?

I just realized this was incorrect. Make it

IF(nYear % 4) = 0 THEN
  IsLeapYr = NOT (nYear % 100 = 0) OR (nYear % 400 = 0)
ENDIF

I think that's right.