 if the half rate clock signal is sampled at a first state, selecting the quadrature of the half rate clock signal or, if the half rate clock signal is sampled at a second state, selecting a digital complement of {HEAD ~ the quadrature} of {TAIL ~ the half rate clock signal}; and 
of
if the half rate clock signal is sampled at a first state , selecting the quadrature of the half rate clock signal or , if the half rate clock signal is sampled at a second state , selecting a digital complement of { HEAD ~ the quadrature } of { TAIL ~ the half rate clock signal } ; and
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH