>What SBT does is ...
>
>QtyOrd field (Quantity Ordered)
>QtyShp field (Quantity Shipped)
>
>Shipment process actually decrements QtyOrd while increasing QtyShp.
>
>If you need to know the amount of the original order it's QtyOrd + QtyShp.
>
>Hope this helps...

SBT is basically a dbase application and in dBase normalizing was not practical.
I would just select sum(shipment.qty) from shipments where shipments.line_id=orderLines.lineid and deduct it from the ordr qty

Peter