When the button Pick has been clicked on in the sales shipment window it generates a picking slip.
On the picking slip is a list of all products that are on the sales shipment and can also list those products that the system thinks needs to go to back order (if the shipment was created from a sales order).
The user uses the picking slip to pick and pack the goods.
The goes back to the computer, scans the barcode on the picking slip, this will automatically bring up the sales shipment from which the user can now complete the shipment.