Anyone else wonder if these powers can also be used for evil? Is that something to worry about as a site admin? --What stop gaps are in place for that sort of thing? sgd > -----Original Message----- > From: Ben Dyer [mailto:ben_dyer at imaginuity.com] > Check out > > http://perl.about.com/compute/perl/library/weekly/aa073000a.htm > > for information about credit card prefixes and the Luhn > algorithm and other > fun things about checking credit card numbers.