Yamaha LS9 Editor Owner's Manual page 43

If a STEREO/MONO channel is selected
● STEREO channel window
● MONO channel window
❏ CHANNEL SELECT (Channel selection)
Except for the fact that your editing applies to a STEREO/MONO channel, this is the same as the channel selec-
tion for a MIX channel (➥ p.37).
43 LS9 Editor Owner's Manual