Codes for geopolitical entities used in the GNS are based on the U.S. Federal Information Processing Standards Publication 10-4 "Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions" (FIPS PUB 10-4).
On September 2, 2008, the U.S. Department of Commerce withdrew FIPS PUB 10-4. The specifics of this action were announced in the U.S. Federal Register / Vol. 73, No. 170. The withdrawal of FIPS 10-4 was based on the Office of Management and Budget (OMB) Circular A-119 Federal Participation in the Development and Use of Voluntary Consensus Standards and in Conformity Assessment Activities. Circular A-119 directs federal agencies to use voluntary consensus standards in lieu of government-unique standards except where inconsistent with law or otherwise impractical.
Following the withdrawal, the National Geospatial-Intelligence Agency (NGA), as the maintenance agency for FIPS PUB 10-4, maintained and provided regular content updates in an informal document known as Geopolitical Entities and Codes (GEC) (formerly FIPS PUB 10-4). GEC maintenance was discontinued on 31 December 2014. A compilation of the complete GEC content as of 31 December 2014 may be found here (GEC_31DEC2014.xlsx). The original GEC recompilation and the 18 GEC Updates may be found here (GEC Updates)
The Geopolitical Entities, Names, and Codes (GENC) Standard, the US Government profile of ISO 3166, has been designated as the replacement standard for FIPS PUB 10-4. GENC provides a list of the basic geopolitical entities in the world, together with the administrative subdivisions that comprise each entity. The names of the geopolitical entities are derived from official meeting records of the Foreign Names Committee of the U.S. Board on Geographic Names (BGN). Further information and the GENC content may be found in the GENC Registry online at: https://nsgreg.nga.mil/genc/discovery.
The GNS will continue to use geopolitical codes based on GEC (formerly FIPS PUB 10-4) for the foreseeable future. Once implementation of GENC codes begins, there will likely be a transition period during which both GEC and GENC codes are available to the GNS user. As more information becomes available it will be posted here.
A crosswalk workbook of GENC and GEC codes is available here (GENC_ED3U5_GEC_XWALK.xlsx). This document will be updated quarterly.