Each half bar holds its two lowest notes as long slots while the three upper notes repeat above them as short ones, so the roll reads as a staircase that changes key every bar.
The leader: tab and eyelet for the take-up spool, the printed label, the start line.The bars on this page, cut into 6 lengths and laid on the bench.
Tempo 70
Over the tracker bar at Tempo 70: a hole sounds, in red, while it is open over the bar.Close up, with the bench ruler in inches and the hole pitch of 1/9 inch.