 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 {HEAD ~ a second state}, selecting {TAIL ~ a digital complement} of the quadrature of the half rate clock signal; and 
selecting
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 { HEAD ~ a second state } , selecting { TAIL ~ a digital complement } of the quadrature of 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 HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH