Requesting the Validation Service {#pa-sdk-implementing-request-validation}
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For enrolled cards, the next step is to make a back-end, server-to-server request for the validation service.  
When you make the validation request, you must:

* Send the consumerAuthenticationInformation.authenticationTransactionId request field.
* Send the credit card information including the PAN, currency, and expiration date (month and year).

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The response that you receive contains the validation result.  
It is recommended that you request the payer authentication and card authorization services at the same time. Doing so automatically sends the correct information to your payment processor and converts the values of these fields to the proper format required by your payment processor:

* consumerAuthenticationInformation.ecommerceIndicator
* consumerAuthenticationInformation.cavv
* consumerAuthenticationInformation.ucafAuthenticationData
* consumerAuthenticationInformation.xid and consumerAuthenticationInformation.xid

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If you request the services separately, manually include the validation result values (Validation Check response fields) in the authorization service request (Card Authorization request fields). To receive liability shift protection, you must ensure that you pass all pertinent data for the card type and processor in your request. Failure to do so might invalidate your liability shift for that transaction. Include the electronic commerce indicator (ECI), the transaction ID (XID), the 3-D Secure version, the directory server transaction ID, and this card-specific information in your authorization request.

* For Visa, JCB,, China UnionPay, Elo, Diners Club, Discover, and American Express include the CAVV.
* For Mastercard only, include the collection indicator and the AAV (also known as UCAF).

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|           Identifier            |                 Validation Check Response Field                 |                Card Authorization Request Field                 |
|---------------------------------|-----------------------------------------------------------------|-----------------------------------------------------------------|
| E-commerce indicator            | consumerAuthenticationInformation.indicator                     | processingInformation.commerceIndicator                         |
| Collection indicator            | consumerAuthenticationInforma tion.ucafCollectionIndicator      | consumerAuthenticationInfo rmation.ucafCollectionIndicator      |
| CAVV                            | consumerAuthenticationInformation.cavv                          | consumerAuthenticationInformation.cavv                          |
| AAV                             | consumerAuthenticationInforma tion.ucafAuthenticationData       | consumerAuthenticationInfo rmation.ucafAuthenticationData       |
| XID                             | consumerAuthenticationInformation.xid                           | consumerAuthenticationInformation.xid                           |
| `3-D Secure` version            | consumerAuthenticationInforma tion.specificationVersion         | consumerAuthenticationInfo rmation.paSpecificationVersion       |
| Directory server transaction ID | consumerAuthenticationInforma tion.directoryServerTransactionId | consumerAuthenticationInfo rmation.directoryServerTransactionId |
[Validation Check and Response Fields]