CJK Unified Ideographs Extension B

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For a list of all CJK characters encoded in Unicode, see CJK Unified Ideographs.
Short description: Unicode character block
CJK Unified Ideographs Extension B
RangeU+20000..U+2A6DF
(42,720 code points)
PlaneSIP
ScriptsHan
Assigned42,718 code points
Unused2 reserved code points
Unicode version history
3.142,711 (+42,711)
13.042,718 (+7)
Note: [1][2]
Historic single-glyph (UCS2003) code chart
File:CJK-B Fontforge.png
A screenshot of a CJK extension B on Fontforge

CJK Unified Ideographs Extension B is a Unicode block containing rare and historic CJK ideographs for Chinese, Japanese, Korean, and Vietnamese submitted to the Ideographic Research Group between 1998 and 2000, plus seven gongche characters for kunqu added in Unicode 13.0, and two characters for the Macao Supplementary Character Set added in Unicode 14.0.[3]

Variation selector sequences

The block has dozens of variation sequences defined for standardized variants.[4] It also has thousands of ideographic variation sequences registered in the Unicode Ideographic Variation Database (IVD).[5][6] These sequences specify the desired glyph variant for a given Unicode character.

Development process

SuperCJK

The repertoire of Extension B was developed by the Ideographic Rapporteur Group in successive revisions of a document named "SuperCJK".[7] This lists all characters included at the time in the Unified Repertoire and Ordering, in Extension A and in the draft Extension B, ordered by radical and residual stroke count. Each character was included with up to four glyph bitmaps, and references to character sources including the Kangxi Dictionary, the Hanyu Da Zidian, and various national character set standards.[8]

"UCS2003" glyphs

Extension B was the only CJK Unified Ideographs Extension block with a UCS2003 source identifier. Since Extension B contained too many characters, the original code charts were produced with a single glyph for all regions. The glyphs were designed by Beijing Zhongyi Electronic Ltd. After the introduction of multi-column code charts on Unicode 5.2, the original glyphs were retained under the UCS2003 source identifier; they were then removed in Unicode 14.0, being redundant as well as misleading.[9] The glyphs are packaged in the "SimSun-ExtB" font distributed with the Simplified Chinese versions of Windows, and do not adhere to the glyphs for the Mainland China region.

Known issues

Ken Lunde noted that what happens in Extension B stays in Extension B. Peter Constable pointed out that we have been dealing with many historical errors in this block over the years.

UTC #187 meeting minutes[10]

Size

Extension B contains 42720 (initially 42711) characters, more than double the 20992 included in the Unified Repertoire and Ordering, and far more than any other CJK extension block (the second-largest of which, as of Unicode 17.0, is CJK Unified Ideographs Extension F, with 7473 characters).[11] This also makes it the only block, besides Private Use Areas, to occupy more than half of the 65534 allocatable codepoints in a Unicode plane.

Owing to its size, a number of mistakes have been discovered in the original version of Extension B since it was encoded.[10][12] To facilitate better review of proposed characters, the working set size for subsequent CJK extension blocks has been kept much smaller; for example, the Ideographic Research Group currently requests that its member bodies should usually submit no more than 2500 characters each, so as to keep the size of the working set below 10000 characters if possible.[13]

Unifiable variants and exact duplicates in Extension B

In CJK Unified Ideographs Extension B, hundreds of glyph variants were encoded.[14] In addition to the deliberate encoding of close glyph variants, seven exact duplicates (where the same character has inadvertently been encoded twice) and two semi-duplicates (where the CJK-B character represents a de facto disunification of two glyph forms unified in the corresponding BMP character) were encoded by mistake:[15]

  • U+34A8 㒨 = U+20457 𠑗 : U+20457 is the same as the China-source glyph for U+34A8, but it is significantly different from the Taiwan-source glyph for U+34A8
  • U+3DB7 㶷 = U+2420E 𤈎 : same glyph shapes
  • U+8641 虁 = U+27144 𧅄 : U+27144 is the same as the Korean-source glyph for U+8641, but it is significantly different from the Chinese Mainland-, Taiwan- and Japan-source glyphs for U+8641
  • U+204F2 𠓲 = U+23515 𣔕 : same glyph shapes, but ordered under different radicals
  • U+21018 𡀘 = U+2103C 𡀼 : same glyph shapes
  • U+249BC 𤦼 = U+249E9 𤧩 : same glyph shapes
  • U+24BD2 𤯒 = U+2A415 𪐕 : same glyph shapes, but ordered under different radicals
  • U+26842 𦡂 = U+26866 𦡦 : same glyph shapes
  • U+FA23 﨣 = U+27EAF 𧺯 : same glyph shapes (U+FA23 﨣 is a unified CJK ideograph, despite its name "CJK COMPATIBILITY IDEOGRAPH-FA23.")

Block

History

The following Unicode-related documents record the purpose and process of defining specific characters in the CJK Unified Ideographs Extension B block:

Version Final code points[lower-alpha 1] Count L2 ID WG2 ID IRG ID Document
3.1 U+20000..2A6D6 42,711 L2/98-260 Ng, Nelson; Kung, Michael (1998-05-26), Report on IRG meeting #11 
L2/99-239 Addition of three hundred and fourteen KANJIs (from JIS X0213), 1999-07-15 
L2/99-310 Addition of three hundred and thirteen KANJIs (from JIS X0213), 1999-08-23 
L2/99-335 N2109 N674 Zhang, Zhoucai (1999-09-03), SuperCJK, version 9.0 with Kangxi and HYD data 
L2/99-336 N2105 N675 CJK Unified Ideographs Extension B WD 6.0, 1999-09-03 
L2/99-316 Whistler, Ken (1999-09-13), Comments on JCS proposal 
L2/99-312 excerpt of usages and sources of proposed KANJIs in contemporary Japanese, 1999-10-06 
L2/99-366 Suignard, Michel (1999-11-24), Text for CD ballot of ISO/IEC 10646 part 2 
L2/99-366.1 Cover page for N3393, 1999-11-24 
L2/99-366.2 Suignard, Michel (1999-11-24), Text of CD 10646-2 
L2/99-366.3 Suignard, Michel (1999-11-24), CJK Ext. B pages 001-100 
L2/99-366.4 Suignard, Michel (1999-11-24), CJK Ext. B pages 101-200 
L2/99-366.5 Suignard, Michel (1999-11-24), CJK Ext. B pages 201-300 
L2/99-366.6 Suignard, Michel (1999-11-24), CJK Ext. B pages 301-335 
L2/99-366.7 Suignard, Michel (1999-11-24), Special Purpose Plane and Annexes 
L2/99-366.8 Suignard, Michel (1999-11-24), Mapping of CJK Ext. B characters 
L2/99-385 N2144 N713R Jenkins, John (1999-12-08), Clarification of the Non-Cognate Rule 
L2/00-010 N2103 Umamaheswaran, V. S. (2000-01-05), Minutes of WG 2 meeting 37, Copenhagen, Denmark: 1999-09-13—16 
L2/00-021R (pdf, rtf) ISO CD 10646 Part-2 vote -- A proposal to move JIS X 0213 Kanji characters on Extension-B into BMP, 2000-01-21 
L2/00-030 Enomoto, Yoshi (2000-01-31), Background of the proposal (for encoding of 302 ideographs from JIS X 0213) 
L2/00-036 Umamaheswaran, V. S.; Sargent, Murray (2000-02-03), Expert contribution on the placement of additional unified ideographs from JIS X0213, HK, and Korea 
L2/01-026 (pdf, doc) N2298 N758 CJK Unified Ideographs Extension B, PreDIS R1 For ISO/IEC DIS 10646-2:2000, 2000-11-21 
L2/01-136 N2334 (pdf, doc) Sato, T. K. (2001-03-28), Notification of an error and request for a correction regarding mapping information for a particular JIS X 0213 character in CJK UNIFIED IDEOGRAPHS EXTENSION-B 
L2/01-163 N2347 N785 CJK Unified Ideographs Extension B PreIS For ISO/IEC 10646-2:2000, 2001-03-30 
L2/01-162 N2349 (pdf, doc) N787 Zhang, Zhoucai (2001-04-02), Clarification On Versions of CJK Unified Ideographs Extension B As Well As SuperCJK 
L2/02-122 N2427 Ksar, Mike (2002-03-18), Proposal to add 1 Hanja code of D P R of Korea into 10646-2:2001 
L2/02-201 N2448 N924 Error Correction, 2002-05-08 
L2/02-416 N2518 Proposal to add 2 hanja codes of D P R of Korea into 10646-2:2001, 2002-11-01 
L2/03-017 Late DPRK Comments on SC 2 N 3625, 10646-2: 2001/FPDAM 1, 2002-12-09 
L2/03-287 Cook, Richard (2003-08-24), 16 UniHan.txt errors 
L2/03-301 Cook, Richard (2003-08-27), 24 more UniHan.txt errors 
L2/03-399 Fok, Anthony (2003-10-13), Unihan reported errors / changes re kHKSCS entries 
L2/03-398 Nguyen, D. (2003-10-29), Unihan reported errors / changes re kCowles 
L2/03-453 Minutes of the Editorial Group Ad Hoc Discussion, 2003-12-17 
L2/04-008 N2695 N1026 China's confirmation on fonts for CJK_B 21E2D and 21E45, 2004-01-05 
L2/04-208 N2774R N1064 Proposal to add 6 KP source references to existing CJK Unified Ideographs, 2004-05-25 
L2/04-281 N2830 Suignard, Michel (2004-06-23), CJK Ideograph source visual references information 
L2/04-417 Cook, Richard (2004-11-18), Extension B font versioning: preliminary work 
L2/05-022 Cook, Richard (2005-01-25), Extension B font versioning: follow-up report, part 1 [text] 
L2/05-023 Cook, Richard (2005-01-25), Extension B font versioning: follow-up report, part 2 [tables] 
N3353 (pdf, doc) Umamaheswaran, V. S. (2007-10-10), Unconfirmed minutes of WG 2 meeting 51 Hanzhou, China; 2007-04-24/27 
L2/07-208 N3285 Proposal to replace 11 KP source references to existing ISO/IEC 10646:2003, 2007-07-18 
L2/08-310 Cook, Richard (2008-08-12), Fonts for Extension B and C and IRG 
L2/10-215 Lunde, Ken (2010-06-22), "Hanyo-Denshi" IVD Collection (PRI 167) to Adobe-Japan1-6 Mapping Table 
N3903 (pdf, doc) Unconfirmed minutes of WG2 meeting 57, 2011-03-31 
L2/11-243 N4111 Sources for Orphaned CJK Ideographs, 2011-06-14 
L2/11-254 Constable, Peter (2011-06-20), UTC Liaison Report from WG2 
N4103 Unconfirmed minutes of WG 2 meeting 58, 2012-01-03 
L2/14-260 N4621 Suignard, Michel (2014-10-23), CJK chart and source references update 
L2/16-052 N4603 (pdf, doc) Umamaheswaran, V. S. (2015-09-01), Unconfirmed minutes of WG 2 meeting 63 
L2/17-180 N2202 Chan, Eiso (2017-06-02), Request for consideration to add kIRG_GSource values to thirteen ideographs and change two G-source glyphs for the Table of General Standard Chinese Characters [Affects U+20164] 
L2/17-362 Moore, Lisa (2018-02-02), UTC #153 Minutes 
N4974 N2301 Request of TCA's Horizontal Extension for Chemical Terminology [Affects U+20BBF, U+20C02, U+20CED, U+26B4C, U+26CBE, U+26E3D, U+28834, U+289A1, U+289C0, U+28A0F, and U+28B46], 2018-06-12 
N4987 Proposal on China's Horizontal Extension for 14 CJK Ideographs [Affects U+20164, 24A7D, 25ED7, 2677C and 26C21], 2018-06-13 
N4988 Proposal on Updating 11 G glyphs of CJK Unified Ideographs to ISO/IEC 10646 [Affects U+21D4C, 2278B, 23AB8 and 2459B], 2018-06-13 
N2336 Modify the G glyph for U+23517, 2018-09-10 
N5016 N2349 Shin, Sanghyun; Cho, Sungduk; Pyo, Seungju; Kim, Kyongsok (2018-12-13), Request to move character K6-1022 in Horizontal Extension of KS X 1027-5 from U+3EAC to U+248F2 
N5020 (pdf, doc) Umamaheswaran, V. S. (2019-01-11), Unconfirmed minutes of WG 2 meeting 67 
N5086 N2379 Proposal of China's horizontal extension for technical used characters [Affects U+23496, U+2355E, U+236ED, U+24726, U+26FE1, U+27334 and U+2A38C], 2019-05-10 
L2/19-237 N5068 Editorial Report on Miscellaneous Issues (meeting IRG#52) [Affects U+23517, U+248F2, and U+26657], 2019-05-17 
L2/19-244 N5107 TCA's UNC Proposal for WG2 submission [Affects U+27C0E], 2019-05-24 
L2/19-241 N5083 N2391 Errata report for WG2 submission_TCA [Affects U+26657], 2019-05-31 
N5082 Updated G Font of U+23517, 2019-05-31 
L2/21-163 N2508 Request for Glyph Change in the H-column of the ISO/IEC 10646 Standard [Affects 22ACF], 2021-08-25 
L2/21-173 Lunde, Ken (2021-09-29), CJK & Unihan Group Recommendations for UTC #169 Meeting [Affects 22ACF] 
L2/22-077 N2512R Shin, SangHyun; Cho, Sungduk; Kim, Kyongsok (2021-11-02), A revised proposal requesting a Horizontal Extension of 51 Hanja chars (previously submitted for ExtF/G/H) [Affects U+20048, 20A1C, 21A5F, 21C08, 21FBA, 23392, 23F4E, 25D20, 26E30, 27BF8, 28633, 28E9A, 29760, and 2A60F] 
L2/21-228 N2520 West, Andrew (2021-11-15), Request to move the source reference for UK-02830 [Affects U+238A7] 
L2/22-022 Lunde, Ken (2022-01-26), CJK & Unihan Group Recommendations for UTC #170 Meeting 
L2/22-016 Constable, Peter (2022-04-21), UTC #170 Minutes 
L2/22-067 Lunde, Ken (2022-04-16), CJK & Unihan Group Recommendations for UTC #171 Meeting 
L2/22-061 Constable, Peter (2022-07-27), Approved Minutes of UTC Meeting 171 
L2/22-238 Bai, Yi; Sim, CheonHyeong (2022-10-16), Proposal to consider adding CodeCharts support for kIRG_KPSource representative glyphs [Affects U+23CC0, 23CD9, 249D6, 249E8, and 24D6A] 
L2/22-256 N2580R T-Source Glyph Correction and Horizontal Extension [Affects U+2486F], 2022-10-18 
L2/22-247 Lunde, Ken (2022-11-01), CJK & Unihan Group Recommendations for UTC #173 Meeting 
L2/22-241 Constable, Peter (2022-11-09), Approved Minutes of UTC Meeting 173 
L2/23-011 Lunde, Ken (2023-01-11), CJK & Unihan Group Recommendations for UTC #174 Meeting 
L2/23-086 N2588R Shin, SangHyun; Kim, Kyongsok; Pyo, Seungju (2023-02-03), A revised proposal requesting a Horizontal Extension of 150 Hanja chars [Affects 134 code points] 
L2/23-089 N2609 Chung, Jaemin (2023-03-15), G glyphs for U+25D89 and U+28BBA 
L2/23-082 Lunde, Ken (2023-04-22), CJK & Unihan Group Recommendations for UTC #175 Meeting 
L2/23-076 Constable, Peter (2023-05-01), UTC #175 Minutes 
L2/23-245 N2642 Jiang, Kushim (2023-09-16), Proposal to update the reference glyphs for 3 characters [Affects U+203D8 and 25B9F] 
L2/23-242 N2651 Proposal to Change Glyph of U+21128, 2023-10-16 
L2/23-237R Lunde, Ken (2023-11-02), CJK & Unihan Group Recommendations for UTC #177 Meeting 
L2/23-231 Constable, Peter (2023-12-08), UTC #177 Minutes 
L2/24-227R Lunde, Ken (2024-10-30), CJK & Unihan Working Group Recommendations for UTC #181 Meeting 
L2/24-221 Constable, Peter (2024-11-12), UTC #181 Minutes, "Accept the proposal to correct the T-source representative glyph for U+277B0" 
N2779R2 T-Source Glyph Modification and Horizontal Extension [Affects U+2752C and others], 2025-03-06 
L2/25-090 Lunde, Ken (2025-04-11), CJK & Unihan Working Group Recommendations for UTC Meeting #183 
13.0 U+2A6D7..2A6DD 7 L2/17-087 Chan, Eiso; Wang, Xiaolei; Le, Hou; You, Jerry (2017-04-03), Proposal to encode characters for Gongche Notation 
L2/17-103 Moore, Lisa (2017-05-18), UTC #151 Minutes 
L2/18-063 N2296 Lunde, Ken (2018-02-22), Proposal to remove the UCS2003 representative glyphs from the Extension B code charts 
N2299 Chan, Eiso (2018-04-22), Request to discuss how to handle seven unencoded Gongche characters for Kunqu Opera 
L2/18-168 Anderson, Deborah; Whistler, Ken; Pournader, Roozbeh; Moore, Lisa; Liang, Hai; Chapman, Chris; Cook, Richard (2018-04-28), Recommendations to UTC #155 April-May 2018 on Script Proposals 
L2/18-245 N4967 Chan, Eiso; You, Jerry; Wang, Xiaolei; Le, Hou (2018-06-01), Updated proposal on Gongche characters for Kunqu Opera 
L2/18-241 Anderson, Deborah (2018-07-20), Recommendations to UTC # 156 July 2018 on Script Proposals 
L2/18-183 Moore, Lisa (2018-11-20), UTC #156 Minutes 
N5020 (pdf, doc) Umamaheswaran, V. S. (2019-01-11), Unconfirmed minutes of WG 2 meeting 67 
N5122 Unconfirmed minutes of WG 2 meeting 68, 2019-12-31 
L2/19-243 N5106 Suignard, Michel (2019-06-20), Disposition of comments on ISO/IEC CD.2 10646 6th edition 
L2/19-270 Moore, Lisa (2019-10-07), UTC #160 Minutes 
L2/20-080 Lunde, Ken (2020-03-16), Proposal to remove the UCS2003 representative glyphs from the Extension B code charts - Redux 
L2/20-102 Moore, Lisa (2020-05-06), UTC #163 Minutes 
14.0 U+2A6DE..2A6DF 2 L2/20-203 N5140 N2437 Submission of 5 Macao SARG UNC Characters and One TCA UNC character, 2020-08-08 
L2/20-235 Lunde, Ken (2020-09-22), Unihan Ad Hoc Recommendations for UTC #165 Meeting 
L2/20-237 Moore, Lisa (2020-10-27), UTC #165 Minutes 
  1. ↑ Proposed code points and characters names may differ from final code points and names

References

  1. ↑ "Unicode character database". The Unicode Standard. https://www.unicode.org/ucd/. Retrieved 2023-07-26. 
  2. ↑ "Enumerated Versions of The Unicode Standard". The Unicode Standard. https://www.unicode.org/versions/enumeratedversions.html. Retrieved 2023-07-26. 
  3. ↑ "18.1: Han (§ Blocks Containing Han Ideographs)", The Unicode Standard: Core Specification, Version 15.0, 2022, pp. 741–744, ISBN 978-1-936213-32-0, https://www.unicode.org/versions/Unicode15.0.0/ch18.pdf#page=6 
  4. ↑ "Unicode Character Database: Standardized Variation Sequences". The Unicode Consortium. https://www.unicode.org/Public/UNIDATA/StandardizedVariants.txt. 
  5. ↑ "Ideographic Variation Database". Unicode Consortium. https://www.unicode.org/ivd/. 
  6. ↑ "UTS #37, Unicode Ideographic Variation Database". Unicode Consortium. https://www.unicode.org/reports/tr37/. 
  7. ↑ Japan National Body (2011-03-01). "Re-confirm on how to use Super CJK document and Japan's concern". https://www.unicode.org/irg/docs/n1754-SuperCJK.pdf. 
  8. ↑ Ideographic Rapporteur Group. "SuperCJK 14.0". https://www.unicode.org/irg/docs/n0802-SuperCJKv14.pdf. 
  9. ↑ "The Unicode Standard, Version 14.0". Unicode Consortium. https://www.unicode.org/versions/Unicode14.0.0/ch24.pdf. 
  10. ↑ 10.0 10.1 "Draft Minutes of UTC Meeting 187: Berkeley, California, United States — April 21-23, 2026". 2026-04-29. https://www.unicode.org/L2/L2026/26093.htm. 
  11. ↑ Lunde, Ken (2025-09-09). "Unicode Version 17.0 CJK Unified Ideographs & CJK Compatibility Ideographs". https://www.unicode.org/irg/docs/n2856-CJKUIv17.pdf. 
  12. ↑ West, Andrew (2007-12-02). "CJK-B Case Study #1: U+272F0". https://babelstone.co.uk/Blog/2007/12/cjk-b-case-study-1-u272f0.html. 
  13. ↑ Lunde, Ken (2026-04-17), IRG Principles & Procedures Version 18, Ideographic Research Group / Unicode Consortium 
  14. ↑ "unifiable glyph variants". http://www.cse.cuhk.edu.hk/~irg/irg/irg25/IRGN1155_Possible_Duplicates.pdf. 
  15. ↑ Cook, Richard. "Defect Report on Duplicate Encoded CJK Forms". https://www.unicode.org/wg2/docs/n2644.pdf. 



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