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