1. In keying, the trigger point or range of a key source signal at which the key or insert takes place. 2. The control that sets this action. To produce a key signal from a video signal, a clip control on the keyer control panel is used to set a threshold level to which the video signal is compared. 3. In digital picture manipulators, a menu selection that blanks portions of a manipulated image that leave one side of the screen and "wraps" around to enter the other side of the screen. 4. In desktop editing, a pointer to a piece of digitized video or audio that serves as source material for editing.