{HEAD ~ Each protrusion} is preferably positioned adjacent {TAIL ~ an inset} 22A or 22B, on the block top surface 10 
is preferably positioned adjacent
{ HEAD ~ Each protrusion } is preferably positioned adjacent { TAIL ~ an inset } 22A or 22B , on the block top surface 10
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH