Special Currency Codes — XAU (Gold), XDR (SDR) & More

Special ISO 4217 Codes (X-Series)

ISO 4217 reserves the letter X as the first character for codes that do not represent a specific country's currency. These cover precious metals, supranational units, testing codes, and other special purposes.

Precious Metals

Code	Metal	Unit	Typical Decimals
XAU	Gold	Troy ounce	2-6
XAG	Silver	Troy ounce	2-6
XPT	Platinum	Troy ounce	2-6
XPD	Palladium	Troy ounce	2-6

These codes allow precious metals to be treated as currencies in financial systems. One "unit" equals one troy ounce (approximately 31.1 grams).

XAU/USD = 2,350.45
Means: 1 troy ounce of gold costs $2,350.45

Portfolio: 10 XAU
Means: 10 troy ounces of gold

Supranational Currencies

Code	Name	Purpose
XDR	Special Drawing Rights	IMF's unit of account, basket of USD, EUR, CNY, JPY, GBP
XBA	European Composite Unit	Bond market unit
XBB	European Monetary Unit	Bond market unit
XBC	European Unit of Account 9	Bond market unit
XBD	European Unit of Account 17	Bond market unit
XSU	Sucre	ALBA trade unit (Latin America)
XUA	ADB Unit of Account	African Development Bank

Special Purpose Codes

Code	Purpose
XTS	Reserved for testing — use in development/staging
XXX	No currency — when the transaction has no monetary aspect
XBA-XBD	Bond market composite units

XDR (Special Drawing Rights)

The SDR is not a currency in the traditional sense but an international reserve asset created by the IMF. Its value is based on a basket of five currencies:

• US Dollar (USD) — ~43%
• Euro (EUR) — ~29%
• Chinese Yuan (CNY) — ~12%
• Japanese Yen (JPY) — ~8%
• British Pound (GBP) — ~8%

SDR amounts appear in IMF transactions, country reserve reporting, and some international treaties.

Using XTS for Testing

When building financial software, use XTS as the currency code in test environments:

{
  "amount": 9999,
  "currency": "XTS"
}

This prevents test transactions from being confused with real ones and clearly marks data as test data.