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The CSO Standard Country Classification is a classification of countries based on the ISO-3166-1:1997 - 'Codes for the representation of names of countries and their subdivisions - Part 1: Country code'. The ISO 3166-1 is an international classification developed by the International Standards Organisation (ISO), and based on a listing of country categories maintained by the United Nations Statistics Division. It must be reviewed at no longer than 5-year intervals and updates are made available on the Internet. The ISO 3166-1 is available from the NSAI website.

In the CSO Standard Country Classification a country is defined as the current name, either short or official (as established by the International Standards Organisation), of a country or dependent territory. This includes:

  • independent countries recognised by the United Nations;
  • administrative subdivisions of certain countries, in particular the United Kingdom;
  • overseas dependencies, external territories of independent countries.

The Classification Board approved the CSO Standard Country Classification on May 6th, 2003. The ISO Maintenance Agency has since agreed to a number of changes to the

ISO-1:1997 'Codes for the representation of names of countries and their subdivisions - Part 1: Country codes': As a result of some of the changes agreed by the ISO 3166/MA, specifically the break up of Yugoslavia, the Classification Board decided to approve a new version, version 2 of the CSO Standard Country Classification on 29th June 2007.


This is a 3-level hierarchical classification with a total of 251 categories:

Level 1 contains 246 categories with 2-character alpha codes. One category of Level 1, GB United Kingdom, is broken down at Level 2 into two categories with 2-character codes, XB Great Britain and XI Northern Ireland. One of these categories, XB, is further broken down at Level 3 into 3 categories with 2-character codes.

This breakdown caters for various survey needs within the CSO. These additional codes come from a list of ISO 3166-1 'user-defined' codes that will never be otherwise assigned in the ISO 3166-1.

Two further categories listed below are not included in the official ISO 3166-1 but have been added to the CSO Standard Country Classification to accomodate the residual category needs of various survey sections. As with the constituent parts of the United Kingdom the code elements are taken from a list of 'user-defined' codes provided by ISO, and will never be used in the ISO 3166-1:

Residual Codes and Descriptors
QM Other
QN Not Applicable

Further Information

Further information on this classification may be obtained from:

Classifications and Standards Section
Central Statistics Office