1. In the old days, an audio tape that was recorded directly from the outputs of a live sound mixing board. Typically the sound quality was less than wonderful, since the soundman builds the mix based on what he hears in the room, which also includes sound spilling off the stage from drums, guitar and bass amps, and so on. Any sound that is loud in the room will not be as loud in the board mix, so it will be under-represented on a board tape.
2. Labeling tape applied to a mixing board to identify the sources routed through the channel strips, etc.