Enumeration Facets Enumeration for what type of data is contained in a Resource. Not strictly a data type, but an indicator of the intended purpose. Pattern Facets ISO 639 language code type restricting to length of 3 and lower case letters ISO 3166 country code type restricting to length of 2 and upper case letters ISO 4217 currency code type restricting to length of 3 and upper case letters ISO 10383 Market Identifier Code type restricting to length of 4 and upper case letters and numbers