This International Standard defines the characteristics of 90 mm Optical Disk Cartridges (ODC) with a capacity of 1,3 GB per cartridge. It specifies only Type R/W for 2048–byte sectors of such cartridges. Type R/W provides for data to be written, read and erased many times over the entire recording surface of the disk using the thermo-magnetic and magneto-optical effects. It is also referred to as "fully rewritable". This International Standard provides for 2 048-byte sectors only. All sectors on a disk are of the same size. This International Standard specifies: − the conditions for conformance testing and the Reference Drive; − the environments in which the cartridges are to be operated and stored; − the mechanical and physical characteristics of the cartridge, so as to provide mechanical interchange ability between data processing systems; − the format of the information on the disk, both embossed and user-written; including the physical disposition of the tracks and sectors, the error correction codes, and the modulation method used; − 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. This International Standard provides for interchange between optical disk drives. Together with a standard for volume and file structure, it provides for full data interchange between data processing systems.