4 ms·
Confusingly Amex has both a 4 digit CID (Front) and 3 digit CSC (Back). The latter I think is only ever used internally by Amex, not for transaction processing.
by notpeter 9y ago
Confusingly Amex has both a 4 digit CID (Front) and 3 digit CSC (Back). The latter I think is only ever used internally by Amex, not for transaction processing.