In many cases, the user will want to inventory single items but will want to buy them as part of a larger purchasing unit. For example, film which may be bought in box quantities.
In these cases, enter the PO Unit Description (i.e. Box) and the Qty per PO Unit. Then, when a purchase order is entered, the system will buy the item in PO units. The inventory, however, will always be updated and maintained as individual items.