Country Code
Following is explained in the ISO20022 Payments Maintenance 2009 document.
Definition: Code to identify a country, a dependency, or another area of particular geopolitical interest,
on the basis of country names obtained from the United Nations (ISO 3166, Alpha-2 code).
Format: [A-Z]{2,2}
Rule(s): The code is checked against the list of country names obtained from the United Nations (ISO 3166, Alpha-2 code).
Example: BE
XMLdation validator checks that country is valid from an external list: http://www.iso.org/iso/country_names_and_code_elements