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