Main stereo master fader

Is the main stereo master fader more like a VCA or Group fader in its behavior?

i.e. Does it adjust the summed volume of all its tracks (like a Group fader) or does it adjust the level by maintaining the relative differences of the track levels (like VCA fader)?

Thank you

I am pretty shure that the stereo master behaves like a group fader.

The master channel is a summing bus, therefore behaves like a group fader.