{HEAD ~ a pull down unit} which pulls down {TAIL ~ the output terminal} of the data transfer unit in response to an output signal from the second logic unit 
pulls down
{ HEAD ~ a pull down unit } which pulls down { TAIL ~ the output terminal } of the data transfer unit in response to an output signal from the second logic unit
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH