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