ISO 4217 "ruble". In addition to codes for most active national currencies ISO 4217 provides codes for "supranational" currencies, procedural purposes, and several things which are "similar to" currencies: The use of an initial letter "X" for these purposes is facilitated by the ISO 3166 rule that no official country code beginning with X will ever be assigned. Because of this rule ISO 4217 can use X codes without risk of clashing with a future country code. ISO 3166 country codes beginning with "X" are used for private custom use (reserved), never for official codes. For instance, the ISO 3166-based NATO country
ISO/IEC 27000 address this. The target audience is users of the remaining ISO/IEC 27000-series information security management standards. ISO/IEC 27000 ISO/IEC 27000 is part of a growing family of ISO/IEC Information Security Management Systems (ISMS) standards, the 'ISO/IEC 27000 series'. ISO/IEC 27000 is an international standard entitled: "Information technology — Security techniques — Information security management systems — Overview and vocabulary". The standard was developed by subcommittee 27 (SC27) of the first Joint Technical Committee (JTC1) of the International Organization for Standardization and the International Electrotechnical Commission. ISO/IEC 27000 provides: ISO/IEC 27000 is available via the ITTF website. (free download) The standard