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