Confusion in identifying if the card is valid or not in Card Verification with Credential on File

Hi
I am implementing the Card Verification with Credential on File because we want to store customer cards on moneris and then will use the key for future payments. So while implementing i didn't find any flag value which gives me exact information that if the card is valid or not i get the message in response but most of the time the message contains other string as well except APPROVED so i want to ask how can i check if the card is valid or not.

Thanks...