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