a) The boundary between two merged video pictures, as created with chroma key or wipe effects.

b) May be thought of as the frame which surrounds a given pattern or key. In the case of a key, the border is on or two lines side, adjustable anywhere from black to white, and may be symmetrical about the key or to the right and bottom (drop shadow). An outline is a special key border where the insert video appears in the border area and the background video fills the hole where the insert would normally be.

In the case of a pattern, the border is adjustable in width and color. A pattern border may be hard colored, soft colored (halo), or soft with no color.

AVC switchers can also do half halo borders, hard on one side and soft on the other.