a) A signal that can electronically “cut a hole” in the video picture to allow for insertion of other elements such as text or a smaller video picture.

b) A video that has been overlaid on top of another video. Keys may W2 W1 B2 B1 SD 5% C Grat. B 2% K2T 5% be either determined by the luminance or brightness of the key video, or determined by the chroma or hue of the key video. c) A push-button.