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 36 ISO/IEC JTC 1/SC 36 ISO/IEC JTC 1/SC 36 Information Technology for Learning, Education and Training is a standardization subcommittee (SC), which is part 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 standards within the field of information technology (IT) for learning, education and training (LET). ISO/IEC JTC 1/SC 36 was established at the November 1999 ISO/IEC JTC 1 plenary in Seoul, Korea. The subcommittee held its first plenary meeting in March 2000 in London, United Kingdom. The international secretariat of ISO/IEC JTC 1/SC