[<< Back to Modular Home](/products/modular)

# Sequence diagrams - SCA Exemptions

### Exemption in authorization (honored)

Please note that exemptions in authentication (3DS) is not yet available.

Exemptions request with a placement in authorization.

Using:

1. [Exemptions API](/products/sca-exemptions/)
2. [Card Payments API](/products/card-payments/)



```mermaid

sequenceDiagram
    participant Browser
    participant Merchant_Frontend
    participant Merchant_Backend
    participant Card_Payments_API
    participant Exemptions_API
    participant Issuers
    Browser-&gt;&gt;Merchant_Frontend: Click Pay
    Merchant_Frontend-&gt;&gt;Merchant_Backend: Pay 
    Merchant_Backend-&gt;&gt;Exemptions_API: Assessment request
    Exemptions_API-&gt;&gt;Merchant_Backend: Assessment response
    Note right of Merchant_Backend: Exemption (e.g.lowRisk/authorization) / Apply riskProfile in Card Payments
    Merchant_Backend-&gt;&gt;Card_Payments_API: customerInitiatedTransactions request
    Card_Payments_API-&gt;&gt;Merchant_Backend: customerInitiatedTransactions response
    Note right of Merchant_Backend: Exemption honored by the issuer
    Merchant_Backend-&gt;&gt;Card_Payments_API: Settlement request
    Card_Payments_API-&gt;&gt;Merchant_Backend: Settlement response
```

### Exemption in authorization (not honored)

Exemptions request with a placement in authorization that is not honored by the issuer. 3DS authentication and an additional card payment is required.

Using:

1. [Exemptions API](/products/sca-exemptions/)
2. [3DS API](/products/3ds/)
3. [Card Payments API](/products/card-payments/)



```mermaid

sequenceDiagram
    participant Browser
    participant Merchant_Frontend
    participant Merchant_Backend
    participant 3DS_API
    participant Card_Payments_API
    participant Exemptions_API
    participant Issuers
    Browser->>Merchant_Frontend: Click Pay
    Merchant_Frontend->>Merchant_Backend: Pay 
    Merchant_Backend->>Exemptions_API: Assessment request
    Exemptions_API->>Merchant_Backend: Assessment response
    Note right of Merchant_Backend: Exemption (lowRisk/authorization) / Apply riskProfile in Card Payments
    Merchant_Backend->>Card_Payments_API: customerInitiatedTransactions request
    Card_Payments_API->>Merchant_Backend: customerInitiatedTransactions response
    Note left of Merchant_Backend: Soft decline (Code 65)
    Merchant_Backend->>3DS_API: deviceDataInitialization request
    3DS_API->>Merchant_Backend: deviceDataInitialization response
    Merchant_Backend->>Merchant_Frontend: DeviceData - BIN/JWT/URL
    Merchant_Frontend->>Browser: 3DS Device Data form
    Browser-->>Issuers: Form POST
    Issuers-->>Browser: PostMessage: dfReferenceId
    Merchant_Backend->>3DS_API: Authentication request
    3DS_API->>Merchant_Backend: Authentication response
    Merchant_Backend->>Merchant_Frontend: Challenge JWT/URL
    Merchant_Frontend->>Browser: 3DS challenge form
    Browser-->>Issuers: Form POST
    Issuers-->>Merchant_Backend: `returnUrl` specified in authentication request
    Note right of Merchant_Frontend: Update or close challenge window on website
    Merchant_Backend->>3DS_API: verification request
    3DS_API->>Merchant_Backend: verification response
    Note right of Merchant_Frontend: Apply authentication details in payment<br> E.g. eci, authenticationValue etc
    Merchant_Backend->>Card_Payments_API: customerInitiatedTransactions request
    Card_Payments_API->>Merchant_Backend: customerInitiatedTransactions response
    Merchant_Backend->>Card_Payments_API: Settlement request
    Card_Payments_API->>Merchant_Backend: Settlement response
```