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 39 Austria, Czech Republic, Islamic Republic of Iran, Ireland, Kenya, Poland, Spain, and Switzerland. ISO/IEC JTC 1/SC 39 has one published standard, ISO/IEC 19395 and is currently working on developing a number of standards within the field of sustainability for and by Information Technology. Some standards within this field currently under development by ISO/IEC JTC 1/SC 39 include: ISO/IEC JTC 1/SC 39 ISO/IEC JTC 1/SC 39 Sustainability for and by Information Technology 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), that develops and facilitates