Describes the general, physical, and magnetic requirements for interchangeability of the one- or two-sided, 5.25 inch (130 mm) (nominal), 96 tracks-per-inch (tpi) (3.8 tracks-per-millimeter (tpmm)) flexible disk cartridge (for 7958 bits-per-radian (bpr) use) as required to achieve unformatted disk cartridge interchange among disk drives using 80 tracks per side and associated information processing systems.