When using the DVP3 as an expression pedal, you can use the internal pot to set the minimum level of the parameter you're controlling with the rocker. If you want to reverse the function of the heel-down and toe-down positions, the DVP3 has an internal switch that allows you to do so.
Along with Volume, FX and Output jacks, the DVP3 also features a convenient Tuner output for silent tuning onstage.