{HEAD ~ One virtual backplane system} includes {TAIL ~ a bus}, and first and second line cards coupled to the bus 
includes
{ HEAD ~ One virtual backplane system } includes { TAIL ~ a bus } , and first and second line cards coupled to the bus
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH