{HEAD ~ A tree structure} resembling {TAIL ~ the packaging hierarchy} is disclosed, where the nodes are referenced by the unique reference, and tracing of entire sub trees may be performed by entering a unique code 
resembling
{ HEAD ~ A tree structure } resembling { TAIL ~ the packaging hierarchy } is disclosed , where the nodes are referenced by the unique reference , and tracing of entire sub trees may be performed by entering a unique code
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH