> ## Documentation Index
> Fetch the complete documentation index at: https://docs.decisionly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Reference IDs

> Link cases to your internal systems with reference IDs

Reference IDs allow you to associate Decisionly cases with your internal system identifiers. These fields enable you to connect cardholders, cards, merchants, and transactions in Decisionly with your existing records.

## Available Reference IDs

You can include reference IDs for the following entities:

* **Cardholder ID** ([`cardholder.issuer_id`](/api-reference/v2-cases/create-a-case#body-cardholder-issuer-id-one-of-0)): Your unique identifier for the cardholder.
* **Card ID** ([`card.issuer_id`](/api-reference/v2-cases/create-a-case#body-transaction-card-issuer-id-one-of-0)): Your unique identifier for the card (not the PAN)
* **Merchant ID** ([`merchant.issuer_id`](/api-reference/v2-cases/create-a-case#body-merchant-issuer-id-one-of-0)): Your unique identifier for the merchant
* **Transaction ID** ([`transaction.issuer_id`](/api-reference/v2-cases/create-a-case#body-transaction-issuer-id-one-of-0)): Your unique identifier for the transaction
* **Program ID** ([`program_id`](/api-reference/v2-cases/create-a-case#body-program-id-one-of-0)): Your unique identifier for the card program the case belongs to

Cardholder ID, Card ID, and Transaction ID are searchable in the Decisionly dashboard, making it easy to find cases using your internal identifiers.

The Program ID field is unique in that cases can be configured to be filtered by card program in the dashboard UI.