In either case, the head of the fastener may have a tapered forward surface portion for engagement with {TAIL ~ the walls} of an access bore in {HEAD ~ an object} to be fastened to the workpiece 
In either case , the head of the fastener may have a tapered forward surface portion for engagement with { TAIL ~ the walls } of an access bore in { HEAD ~ an object } to be fastened to the workpiece
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH