Yeah, but they're used differently - ME goes "above" whatever BGM is playing (without letting you hear the BGM underneath), BGS is a layer above ME/BGM but you can still hear the ME/BGM, and SE is just a normal sound effect (I only listed "stop SE" because now you can stop the SE without playing "(OFF)").

It's a minor feature addition, except for the Stop SE one which is rather useless..

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Err, maybe we can discuss how people always try to make non RPG games with RPG Maker for some reason. That's always confused me..