This International Standard specifies the conditions for conformance testing and the Reference Drive; the mechanical and physical characteristics of the cartridge, so as to provide mechanical interchangeability between data processing systems; the format of the information on the disk, both embossed and user-written; the characteristics of the embossed information on the disk; the magneto-optical characteristics of the disk, enabling processing systems to write data onto the disk; the minimum quality of user-written data on the disk, enabling data processing systems to read data from the disk.