A system and method for providing a security check on a credit card. The credit card has first data recorded thereon in the form of optical gratings to provide for card uniqueness and second data recorded thereon in a magnetic track also located on the card. The optical gratings on the card cannot be...http://www.google.com.au/patents/US4034211?utm_source=gb-gplus-sharePatent US4034211 - System and method for providing a security check on a credit card
