ISO4217

ISO 4217 is a standard published by the International Organization for Standardization that defines internationally recognized codes for currencies and their minor units. It is widely used in banking, accounting, and electronic funds transfer to identify currencies in a consistent way.

The standard assigns each currency a three-letter alphabetic code (alpha-3), a three-digit numeric code, and the number of decimal places used for that currency (the minor unit). The alpha-3 code is usually derived from the currency name or the country name; the numeric code provides a machine-readable identifier; the minor unit indicates the precision in units and subdivisions.

Examples: USD is United States dollar with numeric code 840 and two decimal places; EUR is euro, 978, 2 decimals; JPY is Japanese yen, 392, 0 decimals; GBP is British pound, 826, 2 decimals; AUD is Australian dollar, 036, 2 decimals.

The codes are maintained by the ISO 4217 Maintenance Agency, with changes announced periodically to add new currencies, reassign codes, or retire obsolete ones. In practice, the codes underpin international payment messages (for example SWIFT), card networks, and financial software in order to avoid ambiguity.

ISO 4217 does not define denominations or exchange rates; it only defines the codes and attributes of currencies. The standard has undergone revisions since its introduction in the late 1970s to reflect changes in global currencies.