This International Standard specifies the characteristics of 300 mm optical disk cartridges (ODC) of the WORM type providing for embossed information and for data to be written once and read multiple times. It 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 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. Together with the standard for Volume and File Structure, this International Standard provides for full data interchange between data processing systems. Interchange involves the ability to write and read data without introducing any error.