In this case, this parameter must not be populated.

In case the subscription is successfully created, the response will contain the value generated by the payment gateway.

The merchant website manages the IDs.

In this case, this parameter must be populated with the desired value of the subscription ID.

There is no uniqueness check on the subscription ID.

When creating a subscription, the merchant site can fill vads_subscription with an already existing value.

It is possible to create multiple subscriptions, associated with the same token, with the same subscription ID.

Input and output field, returned in the response (IPN and Return URL).