The vertical radiobuttons represent each set of directions in which the colorref bytes can be rendered (byte_1, byte_2, byte_3; each of which may be rendered in forward or reverse.) The horizontal radiobuttons represent the color with which each variation is weighted. Note that all 48 combinations use the same 216 colors, and each combination is discretely different.

Ok, that description doesn't mean much to me either, let's try it another way... Each pair of horizontal buttons uses two colors that fade to white, and two that fade to black; each button in a given pair flips the direction those fades of each color are rendered. (Both buttons in a given pair fade the same colors.) The vertical buttons change which corner of the cube will be black and which will be white. Those corners always oppose each other. A cube has 8 corners, therefore 8 possibile directions... bah, screw it, I give up.

Each 6x6 table represents a slice of the 6x6x6 cube, upper-left being the front (or top), lower-right being the back (or bottom.)