A standard message type which allows the merchant to check the Card Validation Code (CVC) and, if address details are provided, to optionally use the Address Verification Service (AVS). If these checks are successful Thredd responds with an 00 approval to the merchant. They normally then submit a second transaction, but with an actual transaction amount included. For more information, see the External Host Interface (EHI) Guide. For more information on application of card fees for ASI transaction declines, see the Fees Guide.