PO flip data entry is used to generate an invoice consistent with the data in the information sent by your customer (items, quantities, amounts, discounts and costs).

If you change one of these items when preparing the invoice, SY will display the list of differences identified during invoice validation:

You can either correct these differences by changing the items to make them identical to those in the order (“Change my invoice” option), or you can force invoice processing (“Validate my invoice” option).