The block 14 wherein said block protrusion comprises first and second oblong sections between which is positioned a joining section, said joining section having a narrower width than {HEAD ~ either} of said {TAIL ~ first and second oblong sections} 
of
The block 14 wherein said block protrusion comprises first and second oblong sections between which is positioned a joining section , said joining section having a narrower width than { HEAD ~ either } of said { TAIL ~ first and second oblong sections }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL