The card security codes are 3 or 4 digit codes printed or embossed on Visa, Mastercard, American Express and Discover cards. These codes are also referred to as CVV2, CVC, CSC or CCID. Their purpose is to provide additional protection against fraudulent card use. Below is a list of possible result codes.
| Code | Meaning |
| M | Match |
| N | No Match |
| P | Not Processed |
| S | Should be on card but not so indicated |
| U | Issuer Not Certified |
| X | No response from association |
| (blank) | No CVV2/CVC data available for transaction. |
