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/TC 37 International Standards (and Technical Reports) covering terminological principles and methods as well as various aspects of computer-assisted terminography. ISO/TC 37 is not responsible for the co-ordination of the terminology standardizing activities of other ISO/TCs. ISO 639 Codes for the representation of names of languages, with the following parts: "Note: Current status is not mentioned here - see ISO Website for most recent status. Many of these are in development.": ISO/TC 37 ISO/TC 37 is a technical committee within the International Organization for Standardization (ISO) that prepares standards and other documents concerning methodology and principles for terminology and language resources. Title: