The transaction validation callable service supports the generation and validation of American Express card security codes (CSC). This service generates and verifies transaction values based on information from the transaction and a cryptographic key. You select the validation method, and either the generate or verify mode, through rule-array keywords.

For the American Express process, the control vector supplied with the cryptographic key must indicate a MAC or MACVER class key. The key may be single or double length. DATAM and DATAMV keys are not supported. The MAC generate control vector bit must be on (bit 20) if you request CSC generation and MAC verify bit (bit 21) must be on if you request verification.

The callable service name for AMODE(64) invocation is CSNETRV.