AVANGATE_CUSTOMER_REFERENCE - Default customer numerical (integer) IDs generated automatically by the 2Checkout system.
EXTERNAL_CUSTOMER_REFERENCE - Unique customer alphanumeric (string) identifiers that you control.
The 2Checkout system creates the Avangate Customer ID (AVANGATE_CUSTOMER_REFERENCE) by default for successfully placed orders that include products generating subscriptions. AVANGATE_CUSTOMER_REFERENCE is always included in both IPN and LCN.
Unique customer identifiers (EXTERNAL_CUSTOMER_REFERENCE) that you control are only included in LCN and IPN provided that you set them up via:
- The Buy Link using the CUSTOMERID parameter
- Orders placed using the 2Checkout API
In scenarios in which you don't provide a unique customer identifier, EXTERNAL_CUSTOMER_REFERENCE will be empty in both IPN and LCN when they're first sent out.
Adding a unique customer identifier after the order was finalized won't trigger the LCN on its own. However, the next time that the LCN is generated for updates impacting the license directly, the notification will also include the EXTERNAL_CUSTOMER_REFERENCE you added. The same behavior applies to scenarios in which you move a subscription under a specific customer.