{TAIL ~ A fastener advancing means} intermittently urges the strip of {HEAD ~ fasteners} toward a drive element  
{ TAIL ~ A fastener advancing means } intermittently urges the strip of { HEAD ~ fasteners } toward a drive element
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH