According to the CDS BankingPayeeV2 schema, the Payee description is the description of the payee provided by the customer. How is this different to a Payee nickname? If it is the same, why is the nickname considered mandatory and the description not mandatory?
If you allow a customer to specify a short name and a longer description for a payee you should populate both fields. If you allow only a single label you should populate only the nickname field. If you do not allow the user to define any value you should determine one or more default values to supply in the mandatory field at your discretion.
History behind the two fields
During the initial consultation some banks indicated they allow the customer to label a payee with a nickname, and also provide an additional free form text field with more information. Other banks indicated customers are only able to label a payee with a single free form text string. This was highly dependent on the Consumer experience (CX) they offered their customers in existing channels. The schema was designed to accommodate both standards but not force a data holder to change their existing channels to comply with the schema.