ISO/IEC 26925:2006 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 26925:2006 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.