This International Standard specifies definitions of the essential concepts; the environment in which the characteristics are to be tested; the environments in which the cartridge are to be operated and stored; the mechanical, physical and dimensional characteristics of the case and of the optical disk; the magneto-optical characteristics and the recording characteristics for recording the information, for reading the information and for erasing it many times, so as to provide physical interchangeability between data processing systems; two formats for the physical disposition of the tracks and sectors, the error correction codes, the modulation methods used for recording.