Bola are network news tracks

I think you meant to say "B-roll"!

B-roll is a term used in the film and television industry to describe supplementary footage that is used to support the main action or dialogue in a scene. In the context of network news, B-roll refers to the background footage or video clips that are used to illustrate a news story or provide visual interest to a broadcast.

B-roll can include a wide range of footage, such as:

B-roll is often used to:

In network news, B-roll is typically shot by a team of videographers, photographers, or freelancers who are assigned to cover a specific story or event. The footage is then edited into the final broadcast along with the main story and narration.