ASV SR80 joystick info needed

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I just got a used ASV SR80 and I can not find anywhere in the manual what the thumb switch on the right joystick controls. I know the rocker switch controls the low flow auxillary hydraulics and the trigger button on the front of the joystick controls the 2-speed but I can not find anywhere what the thumb button that is below the rocker button controls. Can anyone tell me??