Abstract: Control valves govern the operation of a plurality of hydraulically-activated devices movable between extended and retracted positions. The control valves are interconnected to a plurality of control lines which carry hydraulic fluid and activation of a particular control valve will establish a certain hydraulic signal pressure pattern within the control lines indicative of a certain commanded position of one of the devices. A decoding section responsive to the signal pressure pattern allows for high pressure hydraulic flow to the selected device and in addition sets up a low pressure return path therefor. A significantly greater number of devices can be controlled with a relatively few control lines thereby reducing construction, maintenance and material costs.