For the toggle commands (Power, Mute) the manual "Edge A & Edge NQ Serial Control Protocol v1.1 " says:
Power/Mute/Volume/Source changes in the Edge unit.
When the power state, mute state, volume level or source is changed in the Edge unit by any means, for example from an IR remote control button press, a Reply message will be sent indicating the new changed state without the external control equipment needing to poll the unit for the current state.
Volume change messages are not sent for every volume step, only when the volume has stabilised at a new level.
Is this helpfull?