In the case of {TAIL ~ a nail}, the plug of filler material would be joined to {HEAD ~ the nail head} 
In the case of { TAIL ~ a nail } , the plug of filler material would be joined to { HEAD ~ the nail head }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD