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 35 ISO/IEC JTC 1/SC 35 ISO/IEC JTC 1/SC 35 User interfaces 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 standards within the field of user-system interfaces in information and communication technology (ICT) environments. The subcommittee was founded at the 1998 Sendai ISO/IEC JTC 1 Plenary meeting, before which it was a working group directly under ISO/IEC JTC 1 (ISO/IEC JTC 1/WG 5). The international secretariat of ISO/IEC JTC 1/SC 35 is AFNOR (Association Française de Normalisation), located in