>The hedge is to consider that any before about the 18th century may be invalid. The Gregorian Calendar wasn't introduced until the 17th century, and wasn't completely in use in the Western World until sometime in the 18th. So the validity any date before that time could be questioned. What a way to start a Friday.:-)

I see your point -- might be best just to catch as invalid any date before whatever year is reasonable in your specific app, not just 0s...