ISO 3166-3
ISO 3166-3 is part of the ISO 3166 standard published by the International Organization for Standardization (ISO), and defines codes for country names which have been deleted from ISO 3166-1 since its first publication in 1974. The official name of the standard is "Codes for the representation of names of countries and their subdivisions – Part 3: Code for formerly used names of countries". It was first published in 1999. Each former country name in ISO 3166-3 is assigned a four-letter alphabetic code. The first two letters are the ISO 3166-1 alpha-2 code  of the former country, while the last two letters are allocated according to the following rules: Besides the former country name and its ISO 3166-3 code, each entry in ISO 3166-3 also contains its former ISO 3166-1 codes, its period of validity, and the new country names and ISO 3166-1 codes used after its deletion from ISO 3166-1. After a country is deleted from ISO 3166-1, its alpha-2 and alpha-3 codes will be transitionally reserved for a transitional period of at least fifty years. After the expiration of the transitional period, these codes are  free to be reassigned. If a country changes its name without any territorial change, its ISO 3166-1 numeric code remains the same. For example, when Burma was renamed Myanmar without territorial change in 1989, its alphabetic codes were changed, but its numeric code has remained the same. Currently, a few ccTLDs using deleted alpha-2 codes are still active or being phased out. However, alpha-2 codes which were deleted before the popularization of the Domain Name System in the late 1980s and early 1990s were never used for the Internet's country code top-level domains (ccTLDs). Likewise, ISO 3166 -2, the ISO standard for country subdivision codes which was first published in 1998, predated the deletion of many alpha-2 codes. Current codes. The following is a list of current ISO 3166-3 codes, with the following columns: "Click on the button in the header to sort by ISO 3166-3 code." Changes. The ISO 3166/MA updates ISO 3166-3 when necessary. The updating of ISO 3166-3 is totally dependent on the updating of ISO 3166-1. ISO used to announce changes in newsletters which updated the currently valid standard, and releasing new editions which comprise a consolidation  of newsletter changes. As of July 2013, changes are published in the online catalogue of ISO only and no newsletters are published anymore. Past newsletters remain available on the ISO website.