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