An alternative method of {HEAD ~ line selection} is illustrated in FIG 20 in which the switch panel contains {TAIL ~ only 4 switches} 61, 63, 63, 64 and a line count display 65 
An alternative method of { HEAD ~ line selection } is illustrated in FIG 20 in which the switch panel contains { TAIL ~ only 4 switches } 61 , 63 , 63 , 64 and a line count display 65
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH 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