There is only 1 place to make a reference/Note with respect to the invoice being charged. That reference only appears in the "Note" field under Payment Details if the transactions details are pulled up. That is inefficient, plus it generates a 2+ page document, when all you need is that particular data element. The receipt feature generates a credit card receipt which does not include that reference. The receipts in Payeezy were better.
Additionally, when you finish a transaction it closes the screen up and the only way to access that "receipt" with the Note field is to go to Transactions and open up the charge. All of this takes too many steps.