Currency code

Currency codes are defined by the International Organization for Standardization (ISO) in the ISO 4217 standard. ISO 4217 includes both three-letter alphabetic and three-letter numeric codes. The three-letter alphabetic codes are indicated by two letters, representing the ISO 3166-1 country code for the country the currency is from, and an additional letter representing the currency.

ISO 4217 includes codes for not only currencies, but also codes for precious metals (gold, silver, palladium and platinum; normally measured in troy ounces) and certain other entities used in international finance, e.g. Special Drawing Rights. There are also special codes allocated for testing purposes (XTS), and to indicate no currency transactions (XXX). These codes all begin with the letter "X".

Supranational currencies, such as the East Caribbean dollar, the CFP franc, the CFA franc BEAC and the CFA franc BCEAO are normally also represented by codes beginning with an "X". However, the Euro is represented by the code EUR; although EU is not an ISO 3166-1 country code, it was used anyway, and in order to do so EU was added to the ISO 3166-1 reserved codes list to represent the European Union. The predecessor to the Euro, the European Currency Unit, had the code XEU.

Over time, new currencies are created and old currencies are discontinued. As a result, the list of codes must be updated from time to time. The ISO 4217 maintenance agency (MA), the British Standards Institution, is responsible for maintaining the list of codes. An incomplete list of obsolete codes can be found at list of currency codes.