From Elendor
Syntax 1: +COM/LIST [ALL]
Syntax 2: +COM/ON [<player>]
Syntax 3: +COM/OFF
Syntax 1 without the ALL keyword gives a list of all channels that you can
join. If you specify the ALL keyword, it lists all channels on the entire
game. Syntax 2 lists all channels that you are currently joined to. If you
also specify a connected <player>, it lists all channels that both you and
that player are joined to. Syntax 3 lists all channels that you are not
currently joined to but that you can join if you wish.