The means for generating the fourth signal, at {TAIL ~ the first output} of the level 2 comparator block, advantageously include an “OR” gate of which the outputs are connected to the first outputs of {HEAD ~ the level 1 comparator blocks} 
The means for generating the fourth signal , at { TAIL ~ the first output } of the level 2 comparator block , advantageously include an “ OR ” gate of which the outputs are connected to the first outputs of { HEAD ~ the level 1 comparator blocks }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH 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 HEAD HEAD