信息技术.双层（DL用DVD-R）用120mm（每面8.54GB）和80mm（每面2.66GB）DVD可记录磁盘

ISO/IEC 12862:2009 specifies the mechanical, physical and optical characteristics of a 120 mm and an 80 mm dual layer DVD recordable disk to enable the interchange of such disks. It specifies the quality of the pre-recorded, unrecorded and the recorded signals, the format of the data, the format of the information zone, the format of the unrecorded zone, and the recording method, thereby allowing for information interchange by means of such disks. This disk is identified as a DVD recordable disk for dual layer (DVD-R for DL). ISO/IEC 12862:2009 specifies the following: 120 mm and 80 mm nominal diameter disks that may be either single or double sided; the conditions for conformance; the environments in which the disk is to be operated and stored; the mechanical and physical characteristics of the disk, so as to provide mechanical interchange between data processing systems; the format of the pre-recorded information on an unrecorded disk, including the physical disposition of the tracks and sectors, the error correcting codes and the coding method used; the format of the data and the recorded information on the disk, including the physical disposition of the tracks and sectors, the error correcting codes and the coding method used; the characteristics of the signals from pre-recorded and unrecorded areas on the disk, enabling data processing systems to read the pre-recorded information and to write to the disks; the characteristics of the signals recorded on the disk, enabling data processing systems to read the data from the disk. ISO/IEC 12862:2009 provides for interchange of disks between disk drives. Together with a standard for volume and file structure, it provides for full data interchange between data processing systems.