The international standard ISO 42 17 of the International Organization for Standardization (ISO) is "Representation of Currency and Capital Codes" (codes representing currency and capital). Each currency has two kinds of codes, the commonly used three-digit code and the rarely used three-digit code. Most three-letter codes consist of ISO 3 166- 1 two-letter codes followed by a letter (usually the first letter of a currency name).

Since the following monetary units are used in many countries or regions, ISO 42 17 can distinguish the currencies of any country or region:

Yuan/yuan/yuan

shield

koruna

Dinar/dinar

Dirham

Franc (French franc)

Rupee (rupee)

Manat (Manat)

Peso (peso/peso)

Pound (pound)

Lira (lira)

riyal

rouble

shilling

When inflation is so serious that the price figure is too large, some currencies will change their face value. When redetermining the face value, sometimes the monetary unit will be changed, but when the unit is unchanged, the ISO 42 17 currency code will still be changed. For example, the Russian ruble code was changed from RUR to ruble, and 1 ruble = 1000 RUR.

The national standard GB/T 12406- 1996 of People's Republic of China (PRC) is equivalent to ISO 42 17: 1990.