can a field have 2 different input masks

[cjamps]

I am wondering if it is possble to have 2 different inputs masks depending is the field starts with a YO.

Is something like this possible?

IF left(nz([fieldname],vbnullstring),2)="yo"
THEN input mask = "LLL00000-0000"
ELSE
input mask = "LL00000-0000"
ENDIF

[RuralGuy]

How about just an input mask of: ?LL00000-0000