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