Nickelodeon G-roll Tracker Bar Data from page 156, "Rebuilding the Player Piano", by Larry Givens, (C) 1963 by the Vestal Press, with revisions courtesy Hal Davis.

G rolls

Starting from left:

 1. Soft pedal
 2. Sustaining pedal
 3. Shutoff (Nickel trip)
 4. Lowest bass note (A#)
17. Middle C
26. Highest bass note (A)
27. Instrument A off
28. Shutoff (nickel trip)
29. Instrument A on
30. Snare drum or castanets
31. Piano expression off
32. Piano expression on
33. Shutoff
34. Bass drum
35. Bass drum and cymbal
36. Tympani or tambourine
37. Instrument B on
38. Rewind to play
39. Instrument B off
40. Lowest treble note (A#)
63. Highest treble note (A)
64. mandolin
65. Triangle or wood block

Roll is 11-1/4 inch wide, 6 channels/inch, on 3.5-inch I.D. core, 5.5-inch flanges.  48 notes in the roll, in two segments; lowest 10 bass notes are teed down an octave, to note C, for total of 58 keys played.