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