When a card-present transaction is submitted, the MagnePrint® of the card read at the transaction point is transmitted along with the card and other transaction data. The MagnePrint risk management tool compares the "transaction MagnePrint value" to a "reference MagnePrint value" already present in the authorization database, calculates the degree of correspondence (the match value) between the two values, and makes a judgment about the card's authenticity based on all available transaction information, including the match value.
In comparing a given "transaction MagnePrint value" to its "reference MagnePrint value", the scoring algorithm assigns a match value between zero (no match) and one (perfect match).
During one test, a run of a million transactions with an acceptance threshold set at 0.5 resulted in a "false accept" rate of zero, that is all attempts to process fraudulent cards were thwarted, and the resulting "false reject" rate was only 0.027 percent.
The authorisation methodology allows each relying party to select an acceptance threshold between zero and one for its transactions, or even to specify a threshold that varies according to the characteristics of the transaction (e.g. more stringent for higher value transactions originating from a fraud prone merchant).