[AccessD] more on that Format() to pad text values question

A small problem that I've notices is that if the string being formatted is
empty or null, Format() returns empty or null, which I understand. However,
is there anyway to force Format() to return something? What if you need 000
instead of empty or null? I can come up with a function or expression
myself, I'm just wondering if I can use Format() to force the digits
instead? 
 
Susan H.