Specifies the characteristics of 90-mm flexible disk cartridges recorded at 31 831 ftprad using modified frequency modulation recording, on 80 tracks on each side. Such flexible disk cartridges are identified as ISO Type 303. Specifies the mechanical, physical and magnetic characteristics of the cartridge, so as to provide physical interchangeability between data processing systems. It also specifies the method of recording, the quality of the recorded signals, the track layout and the track format. Together with ISO 9293, this standard provides for full data interchange between data processing systems.