...
By default, when a Sales Order transaction is entered for a customer address that is assigned to an address set that is assigned to the program, with at least one item belonging to an item set assigned to the program, a site assigned to the program, a carrier assigned to the program, and a transaction date within the program’s date range, the On Invoice program will automatically be applied to the transaction and calculated accordingly. To view the program’s effect(s) on the transactionThe sales program is displayed as a line item, which is for informational use only and cannot be edited. If the order has two or more items that are eligible for the same sales program, the total sales program amount is displayed as the price and the extended amount. If the sales order has items that are eligible for more than one on invoice sales programs, each sales program is displayed as a separate line item.
To adjust the sales program rate or to see more sales program details, click the transaction’s Program Details header toolbar icon and open the Promotions & On Invoice Charges tab.
...