ISO/IEC 8859-9:1999,Information technology — 8-bit single-byte coded graphic character sets — Part 9: Latin alphabet No. 5, is part of theISO/IEC 8859 series of ASCII-based standardcharacter encodings, first edition published in 1989. It is designatedECMA-128 byEcma International andTS 5881 as a Turkish standard.^[2] It is informally referred to asLatin-5 orTurkish. It was designed to cover theTurkish language (and the vast majority of users use it for that language, even though it can also be used for some other languages), designed as being of more use than theISO/IEC 8859-3 encoding. It is identical toISO/IEC 8859-1 except for the replacement of sixIcelandic characters (Ðð,Ýý,Þþ) with characters unique to the Turkish alphabet (Ğğ,İ,ı,Şş). And the uppercase ofi isİ; the lowercase ofI isı.

ISO-8859-9 is theIANA preferred charset name for this standard when supplemented with theC0 and C1 control codes fromISO/IEC 6429. In modern applications Unicode andUTF-8 are preferred; authors of new web pages and the designers of new protocols are instructed to useUTF-8 instead.^[3] Since 2023, less than 0.05% of all web pages use ISO-8859-9,^[4][5] while 2.1% of web pages located in Turkey declare use of ISO-8859-9.^[6] However, theWHATWG Encoding Standard, which specifies the character encodings which are permitted inHTML5 and which compliant browsers must support,^[7] requires that web pages marked as ISO-8859-9 be handled asWindows-1254,^[3] which differs from ISO-8859-9 by using theCR range which ISO-8859-9 reserves forC1 control codes for additional graphical characters instead (analogous to the relationship betweenISO-8859-1 andWindows-1252).

Microsoft has assignedcode page 28599 a.k.a.Windows-28599 to ISO-8859-9 in Windows. IBM has assignedcode page 920 (CCSID 920) to ISO-8859-9.^[8][9] It is published byEcma International asECMA-128.^[10]

Differences fromISO-8859-1 have the Unicode code point number below the character.

• Latin script in Unicode
• Unicode
• Universal Character Set
  • European Unicode subset (DIN 91379)
• UTF-8

• ISO/IEC 8859-9:1999
• Standard ECMA-128: 8-Bit Single-Byte Coded Graphic Character Sets - Latin Alphabet No. 52nd edition (December 1999)
• ISO-IR 148 Right-Hand Part of Latin Alphabet No.5(October 1, 1988)

• ISO/IEC 8859
• Computer-related introductions in 1989
• Turkish language

• Articles with short description
• Short description is different from Wikidata
• Use Oxford spelling from December 2011