MIDI Command to Control Mute on AUX Channels

I have recently started using MIDI to control my GLD-80. I have managed to get MIDI to adjust mute and faders on all of the input channels, but I would like to be able to adjust mute for AUX as well. Has anyone done this or know how to do it?

To set mute off on Input Channel 1, I send this MIDI command: 91 20 01