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
Brazilian National Standards Organization (AMN). ABNT is the exclusive representative of Brazil in the international organizations ISO and IEC and in the regional entities COPANT and AMN. Brazilian National Standards Organization The Brazilian Association of Technical Standards, usually rendered in Portuguese as Associação Brasileira de Normas Técnicas (ABNT) is a private non-profit organization and the normative body which is responsible for technical standards in Brazil, and intends to promote technological development in the country. Brazilian national standards published by the association are named "Norma Brasileira Regulamentadora" and abbreviated NBR. ABNT was founded in 1940. It was officially adopted by the Brazilian government in 1962.