discountCode
The discountCode element has two uses, as explained below.
discountCode as a child of enhancedData
The discountCode element is an optional child of the enhancedData element, but required for Guaranteed Payments. It defines the  discount code as entered during checkout. If the customer did not use a discount code at checkout, you must send this element with a null value.
Type = String; minLength = N/A; maxLength = 100
Parent Elements:
Attributes:
None
Child Elements:
None
discountCode as a child of createDiscount, deleteDiscount, and updateDiscount
The discountCode element is the identifier of a defined discount. You use this element when creating, updating, and deleting a discount applied to a subscription.
Type = String; minLength = N/A; maxLength = 25
Parent Elements:
createDiscount, deleteDiscount, updateDiscount
Attributes:
None
Child Elements:
None