The gap is chosen so that it is smaller than the thickness of the loop regions but larger than the thickness of {HEAD ~ the non loop region} of {TAIL ~ the header tape} 
of
The gap is chosen so that it is smaller than the thickness of the loop regions but larger than the thickness of { HEAD ~ the non loop region } of { TAIL ~ the header tape }
OTH 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 HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL