CJK Unified Ideographs Extension B explained

Rangestart:20000
Rangeend:2A6DF
Script1:Han
3 1:42711
13 0:7
14 0:2
Note:[1] [2]

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.

The block has dozens of variation sequences defined for standardized variants.[3]

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

It 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.[6] 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

Unifiable variants and exact duplicates in Extension B

Also in CJK Unified Ideographs Extension B, hundreds of glyph variants were encoded.[7] In addition to the deliberate encoding of close glyph variants, six 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:[8]

Block

History

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

Count L2 ID WG2 ID IRG ID Document
3.1 U+20000..2A6D6 42,711
N2109 N674
N2105 N675
N2144 N713R
N2103
rtf)
doc) N2298 N758
doc)
N2347 N785
doc) N787
N2427
N2448 N924
N2518
N2695 N1026
N2774R N1064
N2830
doc)
N3285
N1406
doc)
N4111
N4103
N4621
doc)
N2202
N4974 N2301
N4987
N4988
N2336
N5016 N2349
doc)
N2369
N5086 N2379
N5068
N5107
N5083 N2391
N5082 N2391
N2580R
N2556R2
N2609
13.0 U+2A6D7..2A6DD 7
N2296
N2299
N4967
doc)
N5122
N5106
14.0 U+2A6DE..2A6DF 2 N5140 N2437

References

Notes and References

  1. Web site: Unicode character database. The Unicode Standard. 2023-07-26.
  2. Web site: Enumerated Versions of The Unicode Standard. The Unicode Standard. 2023-07-26.
  3. Web site: Unicode Character Database: Standardized Variation Sequences . The Unicode Consortium.
  4. Web site: Ideographic Variation Database. Unicode Consortium.
  5. Web site: UTS #37, Unicode Ideographic Variation Database. Unicode Consortium.
  6. Web site: The Unicode Standard, Version 14.0. Unicode Consortium.
  7. Web site: unifiable glyph variants . 2017-12-01 . https://web.archive.org/web/20060515014033/http://www.cse.cuhk.edu.hk/~irg/irg/irg25/IRGN1155_Possible_Duplicates.pdf . 2006-05-15 . dead .
  8. Web site: Cook . Richard . Defect Report on Duplicate Encoded CJK Forms . ISO/IEC JTC1/SC2/WG2 . 6 October 2003 . 2012-03-28 .

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