> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/tokenization/implement-tokenization/card-tokenization-request/processing-the-decision/decision-engine/data-validation-codes.md).

# Data validation codes

Data validation codes help the Issuer analyze how D1 evaluates a Tokenization request.

D1 generates these codes when it validates data received from the payment network TSP and from the Issuer.

### Code groups

D1 returns two code groups:

* **Wallet reason codes** describe the recommendation context provided by the token requestor or wallet provider. D1 normalizes these values across payment network TSPs and wallet providers.
* **Verification codes** describe the checks performed by D1 on the data provided by the token requestor, payment network TSP, and Issuer.

### Where to access the codes

You can access these codes in the following D1 APIs:

* `Notify Card Operations` in the outbound [Card API](/tokenization/integrate-the-d1-api/d1-api-reference/outbound-api-from-d1/card-api.md)
* `Get operation` in the inbound [Card API](/tokenization/integrate-the-d1-api/d1-api-reference/inbound-api-to-d1/card-api.md)

### DIGITIZE response fields

For a `DIGITIZE` operation, the codes are returned in the `details` section:

* `digitizationInformation.digitizationChecks`
  * `.verificationCodes`
* `digitizationInformation.digitizationChecks`
  * `.digitalCardRequestorAssessment.reasonCodesRecommendationDescription`

### Code lists

Use the following pages for the full code lists:

* [Wallet reason codes](/tokenization/implement-tokenization/card-tokenization-request/processing-the-decision/decision-engine/data-validation-codes/wallet-reason-codes.md)
* [Verification codes](/tokenization/implement-tokenization/card-tokenization-request/processing-the-decision/decision-engine/data-validation-codes/verification-codes.md)

{% hint style="warning" %}
D1 can add, change, or remove these codes at any time based on updates from token requestors and payment network TSPs.

Do not hard-code these values in your system.
{% endhint %}


---

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