All Autopiano actions were three-tier, and with horizontal secondary valves. The renowned double-hole tracking system was always used, as it was in "Standard" actions (see System 1). The distinguishing feature between Standard and Autopiano was that in the Autopiano the tracking pneumatics were always in a vertical position, whereas on the Standard they were horizontal and not separated by the valve box. The tracker bars of both had two adjacent staggered holes to "read" both edges of the paper. Tracking systems of other player actions, with the one exception of some Kimball actions, did not have the double holes and so with that exception, it would narrow it down to either Autopiano or Standard. Pictured below is the Autopiano action. For more information about the Standard Player Action Company, the Autopiano Co, and the Auto Pneumatic Action Co., click here.