Works with CiviCRM 4.5. It might not be supported anymore.
This extension add the nationality field to individuals. The option group is filled from a text file in the extension.
Screenshot (click to enlarge)
Since CiviCRM 5.x, extension releases compatible with CiviCRM 5.0 are compatible with 5.0 and later. An extension release compatible with 5.25, for example, means that it requires CiviCRM 5.25 or later.