The jackbox is the switching mechanism for automatic Duo Art rolls.  This is the "Assignment" point of the Jackbox.  Each toggle has at least two wiring posts for connecting stops, couplers, and swell shades. The flexibility of the system allows the Duo Art Organ roll to control almost all organs.   By custom wiring these posts, the available resources of an organ can be assigned to appropriate posts for Duo Art control.  Each group of posts has a number which is faintly visible. These numbers correlate to the holes in the tracker bar.    In this photo, the custom wiring has not been installed as the center channel is empty.  The wires present all lead to the toggles.  At the top right hand is the eight post array for the "Echo coupler" which is tracker bar hole #2.    This eight post array allows toggle #2 to couple the echo division to the upper holes and also turn on as many as seven echo stops.