How are discounts applied to PO in Sage 300?

I understand how to set up discount terms in A/P, but when and how are they applied? In the PO Order Enty and Receipt Entry screens, in the table, the discount is not showing it is calculated against the line item. In the Terms Tab of the PO Invoice Entry screen, it shows the calculation for the discount applied to the invoice as a whole, but is not stated in the Totals Tab.