{HEAD ~ Lead} 168 corresponds to {TAIL ~ lead} 68, illustrated in FIG 1, with sensor 164 corresponding to sensor 64 
corresponds to
{ HEAD ~ Lead } 168 corresponds to { TAIL ~ lead } 68 , illustrated in FIG 1 , with sensor 164 corresponding to sensor 64
HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH