A data medium in the form of a check card is known. Such check cards include a memory in which at least one amount of money is stored. If the user wishes to purchase or use a product or service, the amount of money is debited by the vendor. If the vendor intents to defraud the user, or simply makes an...http://www.google.fr/patents/US6047888?utm_source=gb-gplus-shareBrevet US6047888 - Method system and portable data medium for paying for purchases
Method system and portable data medium for paying for purchases
