Upon tacking, the profiles are pulled apart by frictionally engaging an area on {HEAD ~ the outside} of {TAIL ~ the film}, near the profiles, and between the tacks 
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Upon tacking , the profiles are pulled apart by frictionally engaging an area on { HEAD ~ the outside } of { TAIL ~ the film } , near the profiles , and between the tacks
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH