The Line Item Detail - List Price Discount Amount and Percent fields display the List Price Discount.
Editing the List Price Discount Amount or Percent on the Line Item Detail screen changes the List Price Discount for the current line item only using the formula List Price Discount = Line Item Price - List Price. Editing either field automatically updates the other field. It also changes the Base Price Discount Amount to the right of the Base Price field and the Base Price Discount Percent to the right of the Base Price Discount Amount field. Also updated are the Sales Tax, Price, Total w/ Tax It, and Cost Percent fields. It does not change the List Price Discount Amount field in the item's Inventory database record.
See:
Line Item Detail Screen Contents
Sales Manager Contents