# Response codes

# Mapping of response codes to desired process flow

In the response message the field `scaIndicator` can have the following values:

| Value             | Process flow                            | Values of `rtsExemption` | Related `threeDSRequestorChallengeInd`                         | Description                                                                                                                        |
| ----------------- | --------------------------------------- | ------------------------ | -------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| NO\_SCA\_REQUIRED | No 3DS; Route directly to authorisation | TRA, LOV, EEA, MIT, REC  | not supported                                                  | Transaction is eligible for exemption over authorisation, related exemption flag for authorisation must be sent                    |
| SCA\_REQUIRED     | Call 3DS                                | NUL                      | 01 - no preference                                             | Transaction is not eligible for exemption thus 3DS call is mandatory, if Issuer ACS applies challenge is not relevant for merchant |
| SCA\_OPTIONAL     | Call 3DS                                | TRA, LOV, EEA, MIT, REC  | 02, 05 - depending on exemption and the supported 3DS protocol | Currently used for exemption over 3DS processing with relevant value of `threeDSRequestorChallengeInd`                             |
| SCA\_STRICT       | Call 3DS                                | NUL                      | 03 - challenge requested                                       | Scoring engine detects fraud scenario and requests challenge                                                                       |
| SCA\_MANDATED     | Call 3DS                                | NUL                      | 04 - challenge mandated                                        | Scoring engine detects fraud scenario and requests challenge                                                                       |
| DECLINE           | Decline to merchant                     | NUL                      | not supported                                                  | Scoring engine detects fraud scenario: No 3DS call/  no authorisation to acquirer ==> decline to merchant                          |

# Endpoints

| Name                        | Endpoint                    | Description                                                                                                      |
| --------------------------- | --------------------------- | ---------------------------------------------------------------------------------------------------------------- |
| SCA exemption request       | `POST /sca-exemptions`      | The endpoint to determine if a transaction is eligible for a SCA exemption and to generate a risk score          |
| SCA exemption learning data | `POST /sca-exemptions-data` | The endpoint to provide the result of a transaction to train the risk engine. This doesn't generate a risk score |