The physical media shall be the 130 mm Magneto-Optical Re-writable Disk with 512 bytes per sector. It shall be compatible with the standard defined in the ISO/IEC 15286:1999 Data Interchange on 130mm Optical Disk Cartridges - Capacity 5.2GB Per Cartridge standard.

Note: The 4.1GB nomenclature refers to the capacity when formatted with 512 bytes per sector compared to the 5.2 GB nomenclature when formatted with 1024 bytes per sector.