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 JTC 1/SC 27 ISO/IEC JTC 1/SC 27 ISO/IEC JTC 1/SC 27 IT Security techniques is a standardization subcommittee of the Joint Technical Committee ISO/IEC JTC 1 of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). ISO/IEC JTC 1/SC 27 develops International Standards, Technical Reports, and Technical Specifications within the field of information and IT security. Standardization activity by this subcommittee includes general methods, management system requirements, techniques and guidelines to address both information security and privacy. Drafts of International Standards by ISO/IEC JTC 1 or any of its subcommittees are sent out to participating national standardization bodies for ballot,