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
International Organization for Standardization end-users of products and services, ensuring that certified products conform to the minimum standards set internationally. The three official languages of the ISO are English, French, and Russian. The name of the organization in French is ', and in Russian, ('). "ISO" is not an acronym. The organization adopted "ISO" as its abbreviated name in reference to the Greek word "" (, meaning "equal"), as its name in the three official languages would have different acronyms. During the founding meetings of the new organization, the Greek word explanation was not invoked, so this meaning may have been made public later.