BUYPurchased parts
CONSIGNEDParts that are provided and owned by a customer
MAKEAn assembly that is built in the manufacturing process
PHANTOM

A phantom assembly is a Bill of Materials assembled for the convenience of the user. It is not actually built or maintained in inventory. This may be useful when the same sequence of parts is used in many different assemblies but the parts are actually assembled at the same time as the top assembly.  Any components reporting to a phantom will be picked and assembled with the assembly to which the phantom reports.