Aha! http://www.wsmr.army.mil/RCCsite/Documents/451-00_Photography,%20Motion%20Picture%20Film%20Cores%20and%20Spools,%20Perforations%20and%20Other%20Technical%20Information/451-00.pdf Go to page D-4... this is the print stock. The camera stock standard is the same except that dimension B is 0.2994 inch instead of 0.3000 inch. --scott