Use this function to change the discount for a part step pricing. Part step pricing is used when you receive better conditions for purchasing more from the supplier, i.e., if you buy more, you could receive a lower price, a better discount, and/or lower additional costs. If there is a conflict in validity between a line on the supplier agreement and a line in Part Step Pricing/Parts, the line from the part step pricing is retrieved to the purchase order line.
The new discount is retrieved to applicable purchase order lines. If you want these new terms to be valid for purchase orders which you have not yet sent to the supplier, you must remove the old lines and add new ones.
Note that it is the cumulative value, including the current purchase order line, that gives you the discount.