Using a mask - data entry


How do you force data to be entered in specific format on a form? One of our forms requires date of birth, even though the HELP text says "Please use the following format when entering date of birth: Sample 01/01/1950" we get all kinds of weird entries. Can I force it the field accept only that input? Yes, this is a "Date" format on the sheet. But because most of the entries are for those 60 and older, they are not going to use the back arrow to get to 1950.

All suggestions would be welcome!