While creating a Draft Sales Quotation when we confirm it, we are directed to a page where we can view Delivery order and Create Invoice.Now once we have created an invoice and on validating it we have the option to either Register Payment or Refund Invoice.

My query is why is the Refund Button functional when we are required to register the payment, its because till now we have n't made the payment hence how can we Refund it. Plz explain