This International Standard specifies the characteristics of 50 mm Optical Disc Cartridges (ODC) with a capacity of 730 Mbytes per Cartridge. This regulation covers the logical format of removable 50 mm magneto-optical discs used on digital still cameras, digital movie cameras, electronic albums and similar devices and combinations of these devices that record, play or process the digital data of still pictures, motion pictures and audio. This standard specifies the recording and reproducing format and processing method of files of still pictures, motion pictures and audio on 50 mm magneto-optical discs so that the users can use these discs on various compatible devices.