The second on {HEAD ~ disc position} is updated into {TAIL ~ substantial coincidence} with an outermost position within the second data recorded region 
The second on { HEAD ~ disc position } is updated into { TAIL ~ substantial coincidence } with an outermost position within the second data recorded region
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH