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