{HEAD ~ a clasp lower part} having {TAIL ~ a dish shaped cross section} to provide a lower surface and an open top side with upwardly facing edges 
having
{ HEAD ~ a clasp lower part } having { TAIL ~ a dish shaped cross section } to provide a lower surface and an open top side with upwardly facing edges
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH