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