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 999 46, Subcommittee (SC) 9 which develops International Standards for the identification and description of information resources. Ms. Janet Shuter from United Kingdom was project leader for ISO 999. ISO 999 ISO 999 (Information and documentation—Guidelines for the content, organization and presentation of indexes) is an ISO standard which provides the information industry with guidelines for the content, organisation and presentation of indexes to a wide range of documents including books, Periodicals, electronic documents, films, images, maps, and three-dimensional objects. It covers the choice and form of headings and subheadings used in index entries once the subjects to be indexed have