(a) The colour codes for the 24 × 24 matrix are allocated according to that provided by the ISO 3166‑1 Maintenance Agency as follows:
- Code elements having a green background may be used without restriction as ISO-3166‑1 codes and are listed as “Official” in Table 2.
- Code elements having a cyan background may be used without restriction and are listed as “Assignable” in Table 2, but if so, it is preferred that an indication be given that they are not “Official”.
- Code elements having a yellow background may be used as ISO-3166‑1 codes but restrictions may apply for use by other bodies, such as UPU, ITU and WCO. These code elements are listed as “Exceptional” in Table 2.
- Code elements having a grey background have been deleted from ISO 3166‑1 and are listed as “Transitional” in Table 2.
- Code elements having a red background must not be used in ISO 3166‑1 and are listed as “Reserved” in Table 2.
- Code elements having a mauve background are used by WIPO(f) including those allocated by ISO 3166‑1. These code elements are listed as “Not Used” in Table 2.
- Code elements having a blue background are listed as “Assignable” in Table 2(c).
- Code elements having a white background are for assignment by ISO 3166 Maintenance Agency and are not listed in Table 2.
(b)Short names of geonyms in English or acronym or abbreviation of organization on whose behalf a reservation was made.
(c)ISO 3166‑1 is the primary source. Allocation in the ISO 3166‑1 is as provided above(a).
The Conventions on Road Traffic of 1949 and 1968 were published listing one-, two-, and three-letter codes as the distinguishing signs for vehicles, normally represented in capital letters surrounded by an elliptical border. At some stage, the one-letter codes were abandoned in favour of two-letter codes for country identification, but publishers still use of some one-letter codes use on labels for vehicles to indicate that they have been to the country for which the code was originally used. A list of two-letter, three-letter and three-digit codes was first published by ISO in 1974 under ISO 3166:1974. Further editions of ISO 3166 were published in 1981, 1988, and 1993. The introduction of separate two- and three-letter codes for each country probably commenced with the publication of the 1974 edition where countries that had previously been represented by a three-letter code were allocated a two-letter code and vice versa. ISO split the standard into three parts first published in 1997:
- ISO 3166‑1 for two-letter, three-letter, and three-digit codes for countries;
- ISO 3166‑2 for codes for primary administrative subdivisions within countries and
- ISO 3166‑3 for those deleted from ISO 3166 since 1974. The first publication of ISO 3166-1 was dated 1997.
The following list most of the changes:
- 1975: Sikkim (codes SK, SKM) merged with India.
- 1976: Three-letter code for Philippines changed from PHI to PHL.
- 1977: Gilbert and Ellice Islands (codes GE, GEL) split into Gilbert Islands (codes GE, GEL) and Tuvalu.
- South Vietnam (codes VD, VDR, full name Democratic Republic of Viet-Nam) merged with North Vietnam (VN, VNM, full name Republic of Viet Nam) to form Vietnam;
- Name of French Territory of the Afars and Issas (codes AI, AFI, 262) changed to Djibouti;
- Name of Dahomey (codes DY, DHY, 204) changed to Benin.
- French Southern and Antarctic Territories (codes FQ, ATF) split into French Southern Territories and a section corresponding to Adélie Land, which was not given an entry because it was considered part of Antarctica;
- British Antarctic Territory (codes BQ, ATB) merged with Antarctica;
- Name of Gilbert Islands (codes GE, GEL, 296) changed to Kiribati.
- Southern Rhodesia (alpha codes RH, RHO, 716) changed to Zimbabwe;
- Name of New Hebrides (codes NH, NHB, 548) changed to Vanuatu;
- Panama Canal Zone (codes PZ, PCZ) merged with Panama.
- 1983: Dronning Maud Land (codes NQ, ATN, 216) merged with Antarctica.
- Canton and Enderbury Islands (codes CT, CTE, 128) merged with Kiribati;
- Name of Upper Volta (codes HV, HVO, 854) changed to Burkina Faso
- Saint Kitts-Nevis-Anguilla (codes KN, KNA, 658) split into Anguilla and “Saint Kitts and Nevis”;
- Official English name of Spanish Sahara changed to Western Sahara.
- Aruba split from Netherlands Antilles;
- Trust Territory of the Pacific Islands (codes PC, PCI, 582) split into Federated States of Micronesia, Marshall Islands, Northern Mariana Islands, and Palau;
- United States Minor Outlying Islands formed by merging Johnston Atoll (codes JT, JTN, 396), Midway Islands (MI, MID, 488),
- United States Miscellaneous Pacific Islands (PU, PUS, 849), and Wake Island (WK, WAK, 872).
- 1989-12-05 (Newsletter III-1): Official English name of Burma (codes BU, BUR, 104) changed to Myanmar.
- 1990-08-14 (Newsletter III-7):
- People's Democratic Republic of Yemen (short name, Democratic Yemen; codes, YD, YMD, 720) merged with Yemen Arab Republic (short name, Yemen);
- Numeric code changed from 886 to 887; Short name changed to Republic of Yemen.
- 1990-08-14 (Newsletter III-10): Official English name of Kampuchea changed to Cambodia.
- 1990-10-30 (Newsletter III-13): German Democratic Republic (codes DD, DDR, 278) merged with Federal Republic of Germany; Numeric code changed from 280 to 276.
- 1992-04-19 (Newsletter III-22): Official English name of Micronesia changed to Federated States of Micronesia.
- 1992-04-19 (Newsletter III-23): Full name (Ukrainian Soviet Socialist Republic) and short name (Ukrainian SSR) changed to Ukraine; No codes changed.
- 1992-06-15 (Newsletters III-16, 17, 18, 27, 29, 30, 31, 32, 33, 34, 35, 36): Armenia, Azerbaijan, Estonia, Kazakstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russian Federation, Tajikistan, Turkmenistan, and Uzbekistan split from USSR.
- 1992-06-15 (Newsletter III-19): Full name (Byelorussian Soviet Socialist Republic) and short name (Byelorussian SSR) changed to Belarus.
- 1992-06-15 (Newsletter III-26): Croatia split from Yugoslavia.
- 1992-08-28 (Newsletter III-28): Georgia split from USSR.
- 1992-08-30 (Newsletter III-37): USSR (full name Union of Soviet Socialist Republics, codes SU, SUN, 810) changed to “Transitional” — to be discontinued.
- 1993 (Newsletter III-39): Bosnia and Herzegovina split from Yugoslavia.
- 1993-06-15 (Newsletter III-38): Slovenia split from Yugoslavia.
- 1993-06-15 (Newsletters III-49 through III-51): Czechoslovakia (full name Czechoslovak Socialist Republic, codes CS, CSK, 200) split into Czech Republic (CZ) and Slovakia (SK).
- 1993-06-18 (Newsletter III-24): Metropolitan France (codes FX, FXX, 249) added. The standard didn't specify the geographical compass of this entity, but it was clearly intended to represent France in Europe, including Corsica. The entity was later removed from the list (see 1997-07-14) on review of the stated purpose of the ISO 3166‑1 standard.
- 1993-07-02 (Newsletter III-52): Full name of Angola changed from People's Republic of Angola to Republic of Angola.
- 1993-07-12 (Newsletter III-40): Official English name of Republic of Yemen changed to Yemen.
- 1993-07-12 (Newsletter III-46): Neutral Zone (between Saudi Arabia and Iraq, codes NT, NTZ, 536) removed from list. The Neutral Zone was split up, some being allocated to Saudi Arabia and the remainder being allocated to Iraq following the Gulf War of 1991.
- 1993-07-12 (Newsletter III-47): Numeric code of Netherlands Antilles changed from 532 to 530 (a delayed consequence of the splitting off of Aruba).
- 1993-07-12 (Newsletter III-48): Mayotte added to list. It apparently was previously considered part of France, but the standard never said so explicitly.
- 1993-07-12 (Newsletter III-53): Full name of Madagascar changed from Democratic Republic of Madagascar to Republic of Madagascar.
- 1993-07-16 (Newsletters III-55 and III-56): Eritrea split from Ethiopia; numeric code of Ethiopia changed from 230 to 231.
- 1993-07-16 (Newsletter III-57): The Former Yugoslav Republic of Macedonia split from Yugoslavia.
- 1993-07-16 (Newsletter III-58): Full name of Afghanistan changed from Democratic Republic of Afghanistan to Islamic State of Afghanistan.
- 1993-07-22 (Newsletter III-44): Numeric code of Panama changed from 590 to 591 (a delayed consequence of the merging with the Panama Canal Zone).
- 1993-07-23 (Newsletter III-54): South Georgia and the South Sandwich Islands split from Falkland Islands.
- 1993-07-25 (Amendment to Newsletter III-32): Official English name of Kyrgyzstan changed to Kyrgyz Republic.
- 1993-07-28 (Newsletter III-45): Numeric code of Yugoslavia changed from 890 to 891 (a consequence of the splitting off of Bosnia and Herzegovina, Croatia, Macedonia, and Slovenia).
- 1994-01-26 (Newsletter III-59): Full name of Andorra changed from Andorra to Principality of Andorra.
- 1994-01-26 (Newsletter III-60): Full name of Cambodia changed to Kingdom of Cambodia.
- 1996-04-03 (Newsletter IV-1): Short and full names of Vatican City changed from Vatican City State (Holy See) to Holy See (Vatican City State).
- 1997-07-14 (Newsletter IV-2):
- Zaire (full name Republic of Zaire, alpha codes ZR, ZAR) changed to The Democratic Republic of the Congo;
- Metropolitan France removed from the list, but remains an “exceptionally reserved code element”.
- 1998-02-05 (Newsletter V-1): Formal name of Samoa changed from Independent State of Western Samoa to Independent State of Samoa.
- 1999-10-01 (Newsletter V-2): Occupied Palestinian Territory split from Israel.
- 2002-02-01 (Newsletter V-3): Three-letter code for Romania changed from ROM to ROU.
- 2002-05-20 (Newsletters V-4 and V-5): Official English spellings of two country names were changed: Kazakstan to Kazakhstan, and Macau to Macao. The ISO two- and three-letter codes for East Timor were changed from TP to TL and from TMP to TLS, respectively.
- 2002-11-15 (Newsletter V-6): Official English name of East Timor changed to Timor-Leste.
- 2003-01-14 (Newsletter V-7): Formal name of Comoros changed from Islamic Federal Republic of the Comoros to Union of the Comoros.
- 2003-07-23 (Newsletter V-8): Official English name of Yugoslavia changed to Serbia and Montenegro. The alpha codes were changed from YU, YUG to CS, SCG.
- 2004-02-13 (Newsletter V-9): Åland Islands split from Finland. No code change for Finland.
- 2006-03-29 (Newsletter V-11): Guernsey, Isle of Man, and Jersey split from United Kingdom. No code change for United Kingdom.
- 2006-09-26 (Newsletter V-12): Serbia and Montenegro, whose codes were CS, SCG, and 891, split into two countries: Serbia and Montenegro.
- 2007-09-21 (Newsletter VI-1): Saint Barthélemy and Saint-Martin (French part) split from Guadeloupe. No code change for Guadeloupe.
- 2010-12-15 (Newsletter VI-8): Curaçao and Sint Maarten (Dutch part) split from Netherlands Antilles, which was renamed Bonaire, Saint Eustachius and Saba. The codes for Netherlands Antilles, AN, ANT, and 530, were retired.
(d)Exceptionally reserved: Used by the Universal Postal Union (UPU). UPU also uses the purported ISO 3166‑1 code “14” for Mayotte and the the purported ISO 3166‑1 code “15” for French Scattered Islands (Bassas da India, Europa, Juan de Nova, Glorieuses, Tromelin).
(e)The World Intellectual Property Organization (WIPO ST.3) uses ten alpha-2 code elements for particular purposes in its Standard ST.3 which are not assigned in ISO 3166‑1. The ISO 3166/MA have indicated that they will not use these alpha-2 code elements for assignment in ISO 3166 at the present stage.
(f)Allocations of 2-letter codes with a blue background are allocated for this Gazetteer for convenience only. 2-letter codes in grey are generally for obsolete geonyms, but are retained in use if they are used in the bibliographic records of intellectual property databases because such records are expected to remain available indefinitely as citations in the prosecution of intellectual property rights. For 2-letter codes where there is duplication, the WIPO ST.3 standard is preferred over ISO-3166.
(g)The International Telecommunications Union (ITU) uses the corresponding alpha-3 code for Ascension Island, Clipperton Island and Diego Garcia, but online access to the codes ITU actually uses is not freely available. Moreover, accessing ITU's website normally initiates a threat warning in client-side protection systems.
(h)Netherlands Antilles dissolved on 10 October 2010. The code is discontinued in ISO 3166‑1 as from 10 October 2010.
(i)Burma changed its name to Myanmar on 18 June 1989. The code is discontinued in ISO 3166 as from 5 December 1989.
(j)Czechoslovakia dissolved on 1 January 1993. The code is discontinued in ISO 3166 as from July 1993.
(k)Dahomey changed its name to Benin on 30 September 1975. The code is discontinued in ISO 3166 as from 1977.
(l)There is a conflict with the use of the code EA for both the Eurasian Patent Office used by WIPO and Ceuta, Melilla used by the World Customs Organisation (WCO). In this Gazetteer, the WIPO allocation is preferred because the subject matter of the Gazetteer relates to intellectual property, which is within the purview of WIPO. Access to the codes WCO actually uses is not freely available online.
(m)In March 1998, extension of scope to ISO 6166 "Securities - International securities identification numbering system (ISIN)". In August 1999, extension of scope to any application needing to represent the name European Union.
(n)In 1995, ISO requested WIPO to use the code EV for the Eurasian Patent Office; WIPO did not honour that request and does not use the code EV.
(p)The obsolete codes for Estonia, Haiti, Grenada, Saint Lucia, Saint Vincent and Venezuela, were used in a list of car vehicle distinguishing signs notified to the Secretary-General of the United Nations under the 1949 and 1968 Road Traffic Conventions(o).
(q)The obsolete codes Liechtenstein, Libya Fezzan and Bolivia were used as motor vehicle distinguishing signs which are in use but which were not notified to the Secretary-General of the United Nations under the 1949 Road Traffic Convention(o).
(r)The code is discontinued in ISO 3166‑1 as from July 1993.
(s)The code is discontinued in ISO 3166‑1 as from September 1995.
(t)The code is discontinued in ISO 3166‑1 as from September 1992.
(u)The code is discontinued in ISO 3166‑1 as from May 2002.
(v)The code conflict caused by the use of EA as the code for the Eurasian Patent Office is resolved in this Gazetteer by using the user-assiganable code XE for Ceuta, Melilla.
(w)The code is discontinued in ISO 3166‑1 as from July 2007.
(x)The code is discontinued in ISO 3166‑1 as from July 1997.
(y)User assigned codes also known to be used by others:
- ISO 4217 uses codes starting with X as the first two letters of its three-letter currency codes to represent non-country-specific currencies.
- The code XZ is also used by the United Nations Code for Trade and Transport Locations to represent installations in international waters.
- The Unicode Common Locale Data Repository assigns QO to represent Outlying Oceania (a multi-territory region containing Antarctica, Bouvet Island, the Cocos (Keeling) Islands, Christmas Island, South Georgia and the South Sandwich Islands, Heard Island and McDonald Islands, the British Indian Ocean Territory, the French Southern Territories, and the United States Minor Outlying Islands), QU to represent the European Union, and ZZ to represent "Unknown or Invalid Territory"