{HEAD ~ a first logic unit} which logically operates the first data and the first transfer control signal, and outputs {TAIL ~ the result} of the logical operation 
outputs
{ HEAD ~ a first logic unit } which logically operates the first data and the first transfer control signal , and outputs { TAIL ~ the result } of the logical operation
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH