In the case of {HEAD ~ a U shaped staple}, {TAIL ~ the plug} of filler material would be joined to the cross member joining the staple legs 
In the case of { HEAD ~ a U shaped staple } , { TAIL ~ the plug } of filler material would be joined to the cross member joining the staple legs
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH