Yamaha GW10 Owner's Manual page 23

Depending on the preset selected, the Foot Controller turns different groups
of effect blocks on and off. You can instantly check which effect blocks
are enabled for this function by looking at the green ON OFF GROUP
LEDs above the Effect Block buttons. For example, in bank 1, program
number 2, the ON OFF GROUP LEDs above CHO and DLY are lit.
ON OFF GROUP / TUNER
WRITE COPY
DST CHO
Be sure to press the Foot Controller down firmly when using this
NOTE
function; the effect block or blocks may not be properly turned on or off if
the Foot Controller is not pressed down all the way.
These are lit to indicate that the two
corresponding effect blocks can be
turned on/off with the Foot Controller.
SWAP
DLY
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Guided Tour