I made this request four years ago when I worked for a different employer and it still has not been done. EXTREMELY simple people: just add a single decimal numeric field to the Purchase Order Line Item record: Quantity Received! Anyone who has tried to update a PO with multiple line items that have Quantity > 1 understands how gosh darned difficult it can be to identiy what items have or have not been received and whether the PO is fully received. Even BETTER would be a check box to indicate Line Item is fully received (this could automatically check when Quantity = Quantity Received - or could be manual... I would be happy just being able to have the check box either way). I was doing this kind of thing in a flat file database system in 1995! I did it in Microsoft Access in 1988! Basic stuff!
As an added bonus, it would be nice if fully received line items could be slightly highlighted or grayed so someone reviewing the PO could identify at a glance what is left to receive.