Fold - Folds the incoming signal in proportion to the top and bottom controls
Top - Multiplies the top portion of the wave
Bot - Multiples the bottom portion of the wave
Color - Pushes the folded signal to the top and bottom of the waveform like the disting and converts incoming waveforms to square waves. Overall color adds high order odd harmonics.

Note, I put a mild filter on the output as it actually reveals more of the harmonic movement rather than just hearing aliasing.