KOI8-U

KOI8-U (RFC 2319) is an 8-bit character encoding, designed to cover Ukrainian, which uses a Cyrillic alphabet. It is based on KOI8-R, which covers Russian and Bulgarian, but replaces eight box drawing characters with four Ukrainian letters Ґ, Є, І, and Ї in both upper case and lower case.

KOI8-RU is closely related, but adds Ў for Belarusian. In both, the letter allocations match those in KOI8-E, except for Ґ which is added to KOI8-F.

In Microsoft Windows, KOI8-U is assigned the code page number 21866. In IBM, KOI8-U is assigned code page/CCSID 1168.^[1][2][3]

KOI8 remains much more commonly used than ISO 8859-5, which never really caught on. Another common Cyrillic character encoding is Windows-1251. In the future, both may eventually give way to Unicode.

KOI8 stands for Kod Obmena Informatsiey, 8 bit (Russian: Код Обмена Информацией, 8 бит) which means "Code for Information Exchange, 8 bit".

The KOI8 character sets have the property that the Russian Cyrillic letters are in pseudo-Roman order rather than the natural Cyrillic alphabetical order as in ISO 8859-5. Although this may seem unnatural, it has the useful property that if the eighth bit is stripped, the text can still be read (or at least deciphered) in case-reversed transliteration on an ordinary ASCII terminal. For instance, "Код Обмена Информацией" in KOI8-U becomes kOD oBMENA iNFORMACIEJ (the Russian meaning of the "KOI" acronym) if the 8th bit is stripped.

The following table shows the KOI8-U encoding.^[1][4] Each character is shown with its equivalent Unicode code point.

Although RFC 2319 says that character 0x95 should be U+2219 (∙), it may also be U+2022 (•) to match the bullet character in Windows-1251.

Some references have a typo and incorrectly state that character 0xB4 is U+0403, rather than the correct U+0404. This typo is present in Appendix A of RFC 2319 (but the table in the main text of the RFC gives the correct mapping).

• KOI character encodings
• Ukrainian alphabet

• Flohr, Guido (2016) [2006]. "Locale::RecodeData::KOI8_U - Conversion routines for KOI8-U". CPAN libintl-perl. 1.1. Archived from the original on 2017-01-15. Retrieved 2017-01-15.
• RFC 2319
• "KOI8-U (RFC 2319)". Kermit. Columbia University. Retrieved 2020-06-24.
• Leishner, Mark (2008) [1999-12-20]. "KOI8-U Belorussian/Ukrainian Cyrillic to Unicode 2.1 mapping table - Based on RFC 2319". Department of Mathematical Sciences, New Mexico State University. Archived from the original on 2017-02-19. Retrieved 2017-02-19.
• Kornai, Andras; Birnbaum, David J.; da Cruz, Frank; Davis, Bur; Fowler, George; Paine, Richard B.; Paperno, Slava; Simonsen, Keld J.; Thobe, Glenn E.; Vulis, Dimitri; van Wingen, Johan W. (1993-03-13). "CYRILLIC ENCODING FAQ Version 1.3". 1.3. Archived from the original on 2017-02-18. Retrieved 2020-06-24.

• Czyborra, Roman (1998-11-30) [1998-05-25]. "The Cyrillic Charset Soup". Archived from the original on 2016-12-03. Retrieved 2016-12-03.
• Hohlov, Yu. E. "Cyrillic Information Representation in Electronic Form - Character Set (Code Page) Tables". Archived from the original on 2016-12-05. Retrieved 2016-12-05.
• Nechayev, Valentin (2013) [2001]. "Review of 8-bit Cyrillic encodings universe". Archived from the original on 2016-12-05. Retrieved 2016-12-05.
• https://web.archive.org/web/20050206230944/http://www.net.ua/KOI8-U/