Yamaha MU90R Owner's Manual page 125

UTILITY MODE
Output Select Lock (OutSel Lock)
Receive General MIDI Exclusive (RcvGMExcl)
116
This determines whether the Equalizer settings (page 57) are initial-
ized or change in response to incoming MIDI messages. When this
is set to "on," the current Equalizer settings are maintained, ignor-
ing any EQ-related messages that are received with XG System On
or GM System On messages, allowing you to protect your original
Equalizer settings. When set to "off," the Equalizer changes accord-
ing to incoming XG/GM System On messages. This setting affects
the Multi mode only, and not the Performance mode.
This determines whether or not the Output Select settings (pages 72,
79) are reset when receiving a GM System On or XG System On
message. It also determines whether the Output Select setting for a
Part can be edited via MIDI or not. If you want to "lock" the Out-
put Select settings and keep them from being changed, set this to
"on."
This determines whether GM System On or XG System On mes-
sages are received or not. The on setting allows these messages to
be received.