The flip flop provides {HEAD ~ an output} that is only dependent on the very fast fall times of the outputs of {TAIL ~ the basic level shifter} 
The flip flop provides { HEAD ~ an output } that is only dependent on the very fast fall times of the outputs of { TAIL ~ the basic level shifter }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL