Is PO number master data or transaction data? Briefly explain

Question: Is PO number master data or transaction data? Briefly explain. This is for Enterprise Systems class that I’m currently taking. Here is the PO number explanation and use.

Customer purchase order number

– Number that the customer uses to uniquely identify a purchasing document (e.g. an inquiry or a purchase order).

Use

– The number creates the link between the customer purchase order and the sales document that you create. You can use the number used by the customer during correspondence with the customer to find certain document information. If the number refers to a purchase order, you can also print it on the documents that you send to the customer (e.g. on the delivery note).