I am creating a form that has a field which will only be allowed to accept one of two values (for security purposes, it can't be a drop down or radio button, the user has to know what it is from a different source).
For example I would like to only allow either 4521 or 4522 in this field, and if it's not one of those two, present a message to the user.
Any suggestions on how best to validate the field entry? (I'm a newbie...)
TIA,
Matt