{HEAD ~ The block} has two side extensions extended inward of {TAIL ~ the notches} of the base 
{ HEAD ~ The block } has two side extensions extended inward of { TAIL ~ the notches } of the base
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH