ISO 3166-3 defines codes for outdated ISO 3166-1country codes and is part of the ISO 3166standard published by the International Organization for Standardization (ISO). 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.
ISO 3166-3 contains an entry for each formerly used country name whose codes were withdrawn from ISO 3166 since the first edition was published in 1974, and assigns a four-character alphabetic code for each entry. The first two characters are the withdrawn ISO 3166-1 alpha-2 code of the country, while the last two characters are allocated according to following rules:
If the country changed its name, the new ISO 3166-1 alpha-2 code is used (e.g., Burma changed its name to Myanmar, whose new code is MM), or the code AA is used if the alpha-2 code is not changed (e.g., Byelorussian S.S.R. changed its name to Belarus, and its alpha-2 code is not changed).
If the country merged into an existing country, the ISO 3166-1 alpha-2 code of this country is used (e.g., German Democratic Republic merged into Germany, whose code is DE).
If the country split up into several parts, the special code HH is used to indicate that there is no single successor code, with the exception of Serbia and Montenegro, which uses XX to avoid confusion with Czechoslovakia, since the same code CS was assigned to the two countries during different periods.
Current codes
Following is a list of current ISO 3166-3 codes. For each entry, the ISO 3166-3 four-letter code is given first, followed by the former country name, its original code elements (alpha-2, alpha-3, numeric), their period of validity, and finally any related notes.
Once five years have passed from the time of withdrawal, the two-letter code is free to be reassigned, as has been done with AI, CS, GE, and SK. However, some of the two-letter codes remain transitionally reserved for a longer period.
Many of the two-letter codes were withdrawn before the introduction of the domain name system, and so were never used for the Internet's country code top-level domains (ccTLDs). However, some ccTLDs using withdrawn codes are still currently active, such as .su, .tp, and .yu.
The alpha-2 code CS had been withdrawn twice, the first time due to the split of Czechoslovakia and the second time due to the split of Serbia and Montenegro. On 2006-09-26 (Newsletter I-4), the code CSHH was assigned to Serbia and Montenegro, even though it had already been used for Czechoslovakia. To avoid confusion, since 2006-12-01 (Newsletter I-5), the code CSXX is used for Serbia and Montenegro.
If the country only changed its name without any territorial changes, its numeric code remains the same.
Alphabetical codes taken from "Srbija i Crna Gora", its Serbian name
Split up into Montenegro (ME, MNE, 499) and Serbia (RS, SRB, 688) CS is currently transitionally reserved