Type of currency in which the price is presented.
Best Practice: Although this is an optional attribute, best practice would be to include it for every price where it is known. The attribute can take any value, but best practice is to use the ISO 4217 “currency code” values. These are 3-letter, all upper case codes that are NOT the same as the ISO country codes. Examples include:
These codes are defined by ISO in ISO 4217 and listed at: https://www.currency-iso.org/en/home/tables/table-a1.html
United States Dollar in the US and US territories
European Union Euro
Used on Element: <price>
|Text, numbers, or special characters||An abbreviation for a currency, typically using the ISO 4217 three-letter alphabetic codes, for example, “USD” for the United States Dollar.|
|Restriction||@currency is an optional attribute; there is no default.|
... <product product-type="book">... <publisher-name>Wildside Books</publisher-name>, Rockville, MD, 2010, Price: <price currency="USD">$4.99</price>. ISBN: <isbn>1557426805</isbn>, <size units="pages">330</size> p. (paperback)</product> ...