This standard specifies the general, physical, and magnetic requirements for interchangeability of the single-sided flexible disk cartridge - for use at 6631 bits per radian (BPR) - as required to achieve unformatted disk cartridge interchange among disk drives and associated information processing systems. The single-sided flexible disk cartridge (for 6631-BPR use), enclosed in a protective envelope and having at least one recording surface, is of the type intended specifically for use with digital recording reproducing equipment employing access mechanisms capable of positioning to 77 data tracks. This standard is not intended as a substitute for a purchase specification.