A1
Global Admininistrative Unit Layers
en
A2
UN Second Administrative Level Boundary Project
en
Note: the unsalb.org website is no longer accessible, and public access to the boundaries resources has been removed http://www.ungiwg.org/content/united-nations-international-and-administrative-boundaries-resources
A3
Global Administrative Areas
en
A4
ISO Country (3166-1 alpha-2)
en
G1
Geonames
en
G2
OpenStreetMap
en
Note: the code should be formed by prefixing the relevant OpenStreetMap ID with node/ way/ or relation/ as appropriate, e.g. node/1234567