RP 53:1993 : Scene-Change Methods for Printing 35-mm, 16-mm and 8-mm Type S Motion-Picture Film
The Society of Motion Picture and Television Engineers eBooks · 1993
(1.1) This practice specifies the dimensions and location of a scene-change notch or cueing spot for actuating the printer light-change mechanism when printing 35-mm, 16-mm, and 8-mm type S motion-picture films. (See annex A.1 for a frame- count cueing method which is more commonly utilized.) (1.2) Although this practice specifies a notch or a cueing spot for actuating the printer light mechanism, at no time should a film contain both.