Unified Hangul Code

Unified Hangul Code (UHC),[2][lower-alpha 1] or Extended Wansung,[4][lower-alpha 2] also known under Microsoft Windows as Code Page 949 (Windows-949, MS949 or ambiguously CP949), is the Microsoft Windows code page for the Korean language. It is an extension of Wansung Code (KS C 5601:1987, encoded as EUC-KR) to include all 11172 Hangul syllables present in Johab (KS C 5601:1992 annex 3).[4][2] This corresponds to the pre-composed syllables available in Unicode 2.0 and later.

"Code page 949" redirects here. For the IBM code page, see Code page 949 (IBM).
Unified Hangul Code
Layout of the Unified Hangul Code
Alias(es)Windows Code Page 949, IBM Code Page 1363
Language(s)Korean
StandardWHATWG Encoding Standard (as "EUC-KR")[1]
ClassificationExtended ISO 646,[lower-alpha 1] variable-width encoding, CJK encoding
ExtendsEUC-KR
Other related encoding(s)KPS 9566-2003, KPS 9566-2011
  1. Not in the strictest sense of the term, as ASCII bytes can appear as trail bytes, although this is limited to letter bytes.

Wansung Code has the drawback that it only assigns codes for the 2350 precomposed Hangul syllables which have their own KS X 1001 (KS C 5601) codepoints (out of 11172 in total, not counting those using obsolete jamo), and requires others to use eight-byte composition sequences, which are not supported by some partial implementations of the standard.[5] UHC resolves this by assigning single codes for all possible syllables constructed using modern jamo, by making assignments outside of the encoding space used for KS X 1001.

The lead byte range is extended to 0x81–FE, and the trail byte range is extended to 0x41–5A, 0x61–7A and 0x81–FE (in EUC-KR, both ranges are 0xA1–FE). The codes outside the EUC-KR ranges are used for the additional hangul.[6]

Terminology

Unified Hangul Code is not registered with IANA as a standard to communicate information over the Internet.[7] Alternatives include UTF-8. However, the W3C/WHATWG Encoding Standard used by HTML5 incorporates the Unified Hangul Code extensions into its definition of "EUC-KR".[1]

Microsoft assigns Windows-949 the label "ks_c_5601-1987",[8][9] which properly applies to KS X 1001 itself (KS C 5601 being the original name of KS X 1001).[10] The WHATWG treat the label "ks_c_5601-1987" interchangeably with "EUC-KR" with the intent of being "compatible with deployed content".[11] The Unicode Consortium's "OBSOLETE/EASTASIA" collection of withdrawn mappings included mappings for Unified Hangul Code as "KSC5601.TXT", with the automatically derived mappings for 7-bit KS X 1001 being included as "KSX1001.TXT".[12]

IBM's code page 949 is another, otherwise unrelated, extension of EUC-KR. International Components for Unicode (ICU) uses "cp949", "949" or "ibm-949" to refer to that IBM code page,[13] and "ms949" or "windows-949" (or several variants of "ks_c_5601-1987") to refer to the Windows mapping of UHC.[14] Python, by contrast, recognises "cp949", "949", "ms949" and "uhc" as labels for UHC, and does not include an IBM-949 codec.[15] Out of the labels incorporating the code page number, the WHATWG recognise only "windows-949".[11]

IBM's code page for Unified Hangul Code is called Code page 1363 (IBM-1363), or "Korean MS-Win". It is a combination of SBCS Code page 1126 and DBCS Code page 1362.[16][17][18][19][20] It differs in having a single byte mapping of 0x5C to the Won sign (U+20A9);[21][22][23] Windows maps 0x5C to U+005C (the Unicode code point for the backslash) as in ASCII,[14] although fonts often still render it as a Won sign.[24] Unicode mapping of the wave dash (0xA1AD) also differs, with the IBM mapping favouring U+301C,[25] while the Microsoft mapping favours U+223C (Tilde Operator).[26] The IBM mapping for UHC is available as "ibm-1363" in ICU,[21] whereas the ICU "windows-949" codec is referred to as IBM-1261 in some ICU source code comments.[27]

Footnotes
  1. Korean: 통합형 한글 코드[3], romanized: Tonghabhyeong Hangeul Kodeu
  2. Korean: 확장 완성형, romanized: Hwagjang Wanseonghyeong

References
  1. van Kesteren, Anne, "5. Indexes (§ index EUC-KR)", Encoding Standard, WHATWG
  2. "INFO: Hangul (Korean) Character Sets", Microsoft Support, Microsoft
  3. "한글 코드에 대하여" (in Korean). W3C.
  4. Zsigri, Gyula (2002-06-18). "KSC and UHC".
  5. Shin, Jungshik. "What are KS X 1001(KS C 5601) and other Hangul codes?". Hangul & Internet in Korea FAQ.
  6. Lunde, Ken (13 January 2009). "Appendix F: Vendor encoding Methods" (PDF). CJKV Information Processing (2nd ed.). O'Reilly Media. ISBN 978-0-596-51447-1.
  7. "Character Sets". Iana.org. Retrieved 2017-01-11.
  8. "Encoding.WindowsCodePage Property - .NET Framework (current version)". MSDN. Microsoft.
  9. "Code Page Identifiers", Windows Dev Center, Microsoft
  10. IBM; Unicode Consortium. "convrtrs.txt". International Components for Unicode. v. 59180.0.1. <quote from="Jungshik Shin"> [...] using KS C 5601 or related names to denote EUC-KR or windows-949 is very much misleading [...] It's just the name of a 94 x 94 Korean coded character set standard which can be invoked on either GL (with MSB reset) or GR (with MSB set).
  11. van Kesteren, Anne. "4.2. Names and labels". Encoding Standard. WHATWG.
  12. Jungshik Shin. "KSX1001.TXT: KS X 1001 to Unicode table". Unicode, Inc.
  13. "ibm-949_P110-1999 (alias cp949)", Converter Explorer, International Components for Unicode
  14. "windows-949-2000", Converter Explorer, International Components for Unicode
  15. "codecs — Codec registry and base classes § Standard Encodings". Python 3.7.2 documentation. Python Software Foundation.
  16. "Coded character set identifiers - CCSID 1363", IBM Globalization, IBM, archived from the original on 2014-11-29
  17. "Code page 1126 information document". Archived from the original on 2017-01-16.
  18. "CCSID 1126 information document". Archived from the original on 2016-03-27.
  19. "Code page 1362 information document". Archived from the original on 2017-03-17.
  20. "CCSID 1362 information document". Archived from the original on 2016-03-27.
  21. "ibm-1363", Converter Explorer, International Components for Unicode
  22. Code Page CPGID 01126 (pdf) (PDF), IBM
  23. Code Page CPGID 01126 (txt), IBM
  24. Kaplan, Michael S. (2005-09-17), "When is a backslash not a backslash?", Sorting it all out
  25. "ibm-1363_P110-1997 (lead byte A1)". ICU Demonstration - Converter Explorer. International Components for Unicode.
  26. "windows-949-2000 (lead byte A1)". ICU Demonstration - Converter Explorer. International Components for Unicode.
  27. See, for reference, ucnv_lmb.cpp (Brendan Murray, Jim Snyder-Grant), where the lead byte 0x11 is commented as referring to "Korean: ibm-1261" after the definition of ULMBCS_GRP_KO, but it is mapped to the "windows-949" ICU codec in the OptGroupByteToCPName array later in the file.
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