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