Each of {HEAD ~ the signals} appearing at {TAIL ~ outputs} 22, 23 and 25 of sequencer 21 is formed of a succession of constant frequency pulses, each pulse corresponding to a passage from one line to the next or to the transformation of a parallel line into a series line  
Each of { HEAD ~ the signals } appearing at { TAIL ~ outputs } 22 , 23 and 25 of sequencer 21 is formed of a succession of constant frequency pulses , each pulse corresponding to a passage from one line to the next or to the transformation of a parallel line into a series line
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH