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