The format can be determined from the first one or two numbers entered in the field: http://en.wikipedia.org/wiki/List_of_Issuer_Identification_Numbers http://

The format can be determined from the first one or two numbers entered in the field: http://en.wikipedia.org/wiki/List_of_Issuer_Identification_Numbers http://en.wikipedia.org/wiki/List_of_Issuer_Identification_N... edit: which doesn't change your point that initial format could move around after you type the first digits. I'll leave this here for trivia.