Order ID. It is also included in the payment confirmation e-mail sent to the buyer.Alphanumeric field. Only one special character, “-”, is allowed.
If any other special characters are used (&, ;, @, etc.), the payment gateway will return an error.
Depending on the payment method, certain restrictions can change the format. This is the case for FacilyPay, Oney, Illicado payments for which the field is mandatory and the format is an9.
Input and output field, returned in the response (IPN and Return URL).