MIDI Show Control (MSC)
A MIDI extension for theatre and live events, letting lighting desks, sound systems and stage machinery share cue commands.
MSC was adopted by the MIDI standards bodies in 1991 and, like MIDI Machine Control, rides on Universal Real Time SysEx. Instead of notes it carries commands such as GO, STOP and RESUME, along with a cue number and a device type: lighting, sound, machinery, video, pyrotechnics. A lighting desk can fire sound cue 42 at the exact moment the lamps come up.
The standard specifies no acknowledgement and no safety guarantees, which becomes a rather pointed omission when the receiver is a pyro rig. In practice MSC is allowed to trigger and humans are left to confirm. Newer installations often move to network control with Open Sound Control or vendors' own protocols, but MSC lingers in plenty of lighting consoles.