Universally available preprinted forms are used in a general purpose printing device to allow for the subsequent verification of the authenticity of a printed document such as a ticket, stamp, check, or money order. In operation, the user accesses the seller of the goods/services and during an information...http://www.google.se/patents/US6505179?utm_source=gb-gplus-sharePatent US6505179 - Verifying the authenticity of printed documents on universally available paper stock
