= usually a distance-framed shot that establishes the spatial relations among important figures, objects, and setting in a scene = a cut where the first shot of someone looking at something is followed by a second shot of what they are presumed to see = a cut where action taking place in the first shot continues in the same direction in the next shot (action seems uninterrupted) = persons appearing to be looking at someone or something in the first shot should be followed by object of their gaze appearing to be located in the direction in which they were looking Example: Having established the spatial relationship between audience members and a speaker, subsequent shots must reflect the original index convergences. If you establish index vectors pointing in different directions, you should maintain the original index divergence in the next shot. Example: two people fighting and looking in opposite directions in initial shot should be doing the same in subsequent close-ups. Having established the direction of a moving object in one shot, you must keep the camera on the same side of the motion vector line in subsequent shots in order to maintain the direction. If you have a guy riding a motorcycle to Wyoming and you show this from screen right to screen left, subsequent shots must also show the motorcycle riding from screen right to screen left (unless , of course, ha has become dissatisfied with Wyoming and is returning to Denver). When cutting during secondary motion (camera movement), you should try to continue that movement in the shot you are cutting to (if you want to maintain continuity). Depending differences in weather, lighting, and white balance settings, colors and other onscreen objects intended to be the same from shot to shot may vary between shooting sessions. Source.