The invoice amount is fully opened by non-deduction of discounts, so the credit invoicing customers, so the average discount is accrued according to the amount of the invoice.
Invoices have opened the full amount without discount. So customers to issue a credit to the perception of the average discount based on the amount of the invoice.
The invoice has turned into a full amount without break discounts. So customers need to direct debit to recognise an average discount by the amount of the invoice .