ISO 4217

Forex, short for Foreign Exchange (Foreign Exchange Currency). Also known as International Market of Foreign Exchange. The foreign currency market (Forex or FX) exists wherever one currency is traded with another (such as an exchange house). The market is largely world’s largest in terms of cash value traded, and includes trade among large banks, central banks, currency speculators, multinational corporations, governments, and other financial markets and institutions . The international standard ISO 4217 was developed by ISO to define the three-letter codes for all the world currencies.
This eliminates the confusion caused by some foreign names such as dollar, franc, peso, or pounds, which are used in many countries but have very different rates.
The first two letters of the code are the two letter country code of the currency according to the standard ISO 3166-1 and the third is usually the initial of the currency itself.
There is also a three-digit code assigned to each currency, so that there is a three-digit code assigned to each country as part of the standard ISO 3166.
This rule also defines the relationship between the principal currency unit and its subdivisions.
The ISO 4217 standard also includes codes for precious metals (gold, silver, palladium and platinum) and other definitions used in the financial world. There are also codes for special tests (XTS), and to indicate no currency transactions (XXX). All these codes start with the letter “X”. The precious metals use “X” and the chemical symbol for the metal (for example, is XAG Silver). ISO 3166 never assigns country codes beginning with “X”, so ISO 4217 can use codes that begin with that letter without risking collisions.

Product Details
Guidelines for Foreign Exchange Reserve Management Accompanying Document And Case Studies (Paperback – May 27, 2005)