| abstract |
There is an optically readable portion (40) as well as a magnetic machine-readable stripe (46) on the document (34). Both have identifying digits. The optically readable portion (40) can include a holographic representation of a bar code or other conventionally known optical digit generator. The machine-read magnetic and optical digit information can be converted into electrical pulses when the document is a credit or chargecard. n A check digit is derived by appending the magnetic and optical digit information and by calculation on the result and is recorded on the magnetic stripe. n Transaction approval is given only if, during reading, the newly calculated check digit matches the recorded check digit. |