Originally Posted by OBP

I don't think that format masks can prevent characters being entered, it can control them.
If you have a field that requires a semicolon at a specifid point the mask can force it's entry and it's position.
Also data validation may not be able to control what you are trying to do with no spaces.

Visual Basic however can be used to test the field after entry and if the Not allowed characters are found they either be deleted or replaced.
You could also in the case of the name with no paces have a first name field and surname field and then concatenate them for the actual table entry.