This Standard ECMA-59 specifies the characteristics of flexible disk cartridges to provide physical interchangeability between data processing systems. It also specifies a standard track format. Together with the labeling system specified in Standard ECMA-58, this track format provides for full data interchange between data processing systems.
ECMA-59
Data interchange on 200 mm flexible disk cartridges using two-frequency recording at 13 262 ftprad on both sides
1st edition, August 1979