{HEAD ~ the output} of the selector element is coupled to {TAIL ~ either the first or the second input} of the selector element as determined by said control signal, and 
is coupled to
{ HEAD ~ the output } of the selector element is coupled to { TAIL ~ either the first or the second input } of the selector element as determined by said control signal , and
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH