ISO/IEC 26925:2009 specifies the mechanical, physical and optical characteristics of 120 mm rewritable optical disks with capacities of 4,7 Gbytes and 9,4 Gbytes. It specifies the quality of the recorded and unrecorded signals, the format of the data and the recording method, thereby allowing for information interchange by means of such disks. The data can be written, read and overwritten many times using the phase change method. These disks are identified as +RW HS (High Speed).
ISO/IEC 26925:2009 also specifies 80 mm disks with capacities of 1,46 Gbytes and 2,92 Gbytes. These disks have the same characteristics as the 120 mm disks, except for some parameters related to the smaller dimensions. All parameters unique for the 80 mm disks are specified in an annex.
ISO/IEC 26925:2009 specifies the following:
- two related but different types of this disk;
- the conditions for conformance;
- the environments in which the disk is to be tested, operated and stored;
- the mechanical, physical and dimensional characteristics of the disk, so as to provide mechanical interchange between data processing systems;
- the format of the information on the disk, including the physical disposition of the tracks and sectors, the error correcting codes and the coding method;
- the characteristics of the signals recorded on the disk, thus enabling data processing systems to read the data from the disk.
ISO/IEC 26925:2009 provides for the interchange of disks between optical disk drives. Together with a standard for volume and file structure, it provides for full data interchange between data processing systems.