|Unique identifier (token or Unique Mandate Reference) associated with a payment method.
- Either this identifier is generated by the payment gateway.
In this case, this parameter must not be populated.
Or it is generated by the merchant website.
In this case, this parameter must be populated with the desired value of the identifier. Caution, it is the responsibility of the merchant website to make sure the identifiers are unique. Any registration request containing an existing identifier will be rejected and an error message will appear.
The input and output field, returned in the response (IPN and Return URL).