In addition to the manual Back Order cancellation process, with the Prohibit Backorder setup we have the ability to do this automatically. The setup is on the "Unit of Measure" and "Customer"/"Vendor" cards, then carried to the sales/purchase order header and can be editable at that level if a User wishes to make an order specific change.
The benefit of this is making the process more efficient for Users so they can pre-define what Customers and Vendors will allow, or Prohibit back-orders. Having this set on the "Customer" or "Vendor" cards can therefore automate the process so that if there is qty outstanding on either the receipt or the shipment, Business Centrals knows whether to close it down (where Back orders are not allowed so no further goods will be added) or remain open, to allow for the full qty to be fulfilled.