Hi Ray,
The only footswitch control for Sustain is On or Off. However, that is just the same as the Sustain Pedal function on an Acoustic piano....
As I'm sure you have discovered, you can set the length of sustain on the KN7000, which you can't do on an Acoustic piano.
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Willum

After silence, that which comes nearest to expressing the inexpressible is Music.
Aldous Huxley
( especially when the music is played on a KN7000....)