# Authentication Value URIs
source: https://developer.mastercard.com/mastercard-send-person-to-person/documentation/field-uris-codes/auth-value-uris/index.md

The following schemas can be used in `authentication_value` fields.

| Schema |                                                                                                                                                                                                             Description                                                                                                                                                                                                             |             Example              |
|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------|
| ucaf   | Universal Cardholder Authentication Field (UCAF) is a cryptographic value. Mastercard® SecureCode™ issuer or cardholder-generated authentication data resulting from all SecureCode fully authenticated or attempts transaction for Mastercard account. This field is populated when a UCAF-enabled merchant has collected authentication data and must pass it in the transaction to the issuer. Data format: string, length: 1-32 | ucaf:jJJLtQa+Iws8AREAEbjsA1MAAAA |
| cavv   | Cardholder Authentication Verification Value (CAVV) is a cryptographic value. Visa issuer or cardholder-generated authentication data resulting from fully authenticated or attempts transaction for Visa account. This field is populated when a merchant has collected authentication data and must pass it in the transaction to the issuer. Data format: string, length: 1-40                                                   | cavv:00000109260000719349        |