The only “override” that comes to mind is the spatializer effect’s “pan override,” but I doubt that’s what your predecessor was talking about, as it doesn’t take place in the mixer.
You can name group buses anything you want by double-clicking on them in the routing browser. You predecessor presumably named those buses “SFX override” and “background music override” because those names were meaningful to them, but overriding isn’t some special FMOD Studio keyword.
That said, it’s relatively common practice to use a sidechain effect on a dialogue bus to duck content on other buses. This is done to prevent a game’s dialogue from getting drowned out by the SFX and music, and it sounds like that’s what your predecessor has done:
- The sidechain effect on the “Dialogue Master” group bus continually monitors the signal at its position, and provides that information to the effects and modulators connected to it.
- The compressor effect on the “SFX Override” group bus has that sidechain effect as one of its inputs. Whenever the signal from that input (i.e.: the signal going through the “Dialogue Master” bus) goes over the value of the compressor effect’s Threshhold property, the compressor effect will compress the signal at its own position (i.e.: the signal going through the “SFX Override” bus).
- The compressor effect on the “Background Music Override” group bus does much the same thing as the other compressor effect, but may have a different Threshhold value or other property values.
So, the net effect is that when an event plays through the “Dialogue Master” group bus, content playing through the “SFX Override” and "Background Music Override"group buses should get slightly quieter. Or at least, that’s what I’m guessing has been done, based on he names of the buses and the fact that there’s a sidechained compressor involved. YOu should be able to test whether this is the case by auditioning the events that route into those buses in the Sandbox window.