Reusing/Duplicating Serial Numbers

Serial numbers by themselves are not unique.  The part/serial number combination are unique though.  Serial numbers may be reused or duplicated provided they are assigned to another the part number.  For example, you may use serial number XX001 for part Screwdriver and for part Hammer at the same time.  You may not use XX001 for Screwdriver twice without some further restrictions.  You may not use a serial number for the same part number twice without a return.  If you shipped part/serial number combination Screwdriver/XX001, it cannot be shipped again until a customer returns it.  Likewise, you could not accept a return for it until it was shipped.

In our World Cereal Corporation example, serial number SN0001BOM has been returned.  Now you can ship it to another customer.