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Han unification is an effort by the authors of Unicode and the Universal Character Set to map multiple character sets of the Han characters of the so-called CJK languages into a single set of unified characters. Han characters are a feature shared in common by written Chinese (hanzi), Japanese (kanji), Korean (hanja) and Vietnamese.
The Ideographic Research Group (IRG), formerly called the Ideographic Rapporteur Group, is a subgroup of Working Group 2 (WG2) of ISO/IEC JTC1 Subcommittee 2 (SC2), which is the committee responsible for developing the Universal Coded Character Set. IRG is tasked with preparing and reviewing sets of CJK unified ideographs for eventual inclusion in both ISO/IEC 10646 and The Unicode Standard. The IRG is composed of representatives from national standards bodies from China, Japan, South Korea, Vietnam, and other regions that have historically used Chinese characters, as well as experts from liaison organizations such as the SAT Daizōkyō Text Database Committee (SAT), Taipei Computer Association (TCA), and the Unicode Technical Committee (UTC). The group holds two meetings every year lasting 4-5 days each, subsequently reporting its activities to its parent ISO/IEC JTC 1/SC 2 (SC2/WG2) committee.
The Chinese, Japanese and Korean (CJK) scripts share a common background, collectively known as CJK characters. During the process called Han unification, the common (shared) characters were identified and named CJK Unified Ideographs. As of Unicode 16.0, Unicode defines a total of 97,680 characters.
CJK Radicals Supplement is a Unicode block containing alternative, often positional, forms of the Kangxi radicals. They are used as headers in dictionary indices and other CJK ideograph collections organized by radical-stroke.
In the Unicode standard, a plane is a contiguous group of 65,536 (216) code points. There are 17 planes, identified by the numbers 0 to 16, which corresponds with the possible values 00–1016 of the first two positions in six position hexadecimal format (U+hhhhhh). Plane 0 is the Basic Multilingual Plane (BMP), which contains most commonly used characters. The higher planes 1 through 16 are called "supplementary planes". The last code point in Unicode is the last code point in plane 16, U+10FFFF. As of Unicode version 16.0, five of the planes have assigned code points (characters), and seven are named.
Kangxi Radicals is a Unicode block. In version 3.0 (1999), this separate Kangxi Radicals block was introduced which encodes the 214 radicals in sequence, at U+2F00–2FD5. These are specific code points intended to represent the radical qua radical, as opposed to the character consisting of the unaugmented radical; thus, U+2F00 represents radical 1 while U+4E00 represents the character yī meaning "one". In addition, the CJK Radicals Supplement block (2E80–2EFF) was introduced, encoding alternative forms taken by Kangxi radicals as they appear within specific characters. For example, ⺁ "CJK RADICAL CLIFF" (U+2E81) is a variant of ⼚ radical 27 (U+2F1A), itself identical in shape to the character consisting of unaugmented radical 27, 厂 "cliff" (U+5382).
A variant form is an alternate glyph for a character, encoded in Unicode through the mechanism of variation sequences: sequences in Unicode that consist of a base character followed by a variation selector character.
CJK Unified Ideographs is a Unicode block containing the most common CJK ideographs used in modern Chinese, Japanese, Korean and Vietnamese characters. When contrasted with other blocks containing CJK Unified Ideographs, it is also referred to as the Unified Repertoire and Ordering (URO).
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.
CJK Unified Ideographs Extension C is a Unicode block containing rare and historic CJK ideographs for Chinese, Japanese, Korean, and Vietnamese submitted to the Ideographic Research Group between 2002 and 2006, plus five "urgently needed" characters added in Unicode versions 14.0 and 15.0, some of which had previously been mistakenly unified with other characters.
CJK Unified Ideographs Extension D is a Unicode block containing uncommon CJK ideographs for Chinese, Japanese, Korean, and Vietnamese, some of which are in current use. Much smaller than most Unicode blocks for CJK unified ideographs, Extension D consists of characters which were submitted to the Ideographic Research Group as "urgently needed characters" between 2006 and 2009. Characters submitted during the same period which were needed less urgently were included in CJK Unified Ideographs Extension E instead.
CJK Compatibility Ideographs is a Unicode block created to contain mostly Han characters that were encoded in multiple locations in other established character encodings, in addition to their CJK Unified Ideographs assignments, in order to retain round-trip compatibility between Unicode and those encodings. However, it also contains 12 unified ideographs sourced from Japanese character sets from IBM.
Enclosed CJK Letters and Months is a Unicode block containing circled and parenthesized Katakana, Hangul, and CJK ideographs. Also included in the block are miscellaneous glyphs that would more likely fit in CJK Compatibility or Enclosed Alphanumerics: a few unit abbreviations, circled numbers from 21 to 50, and circled multiples of 10 from 10 to 80 enclosed in black squares.
CJK Compatibility Forms is a Unicode block containing vertical glyph variants for east Asian compatibility. Its block name in Unicode 1.0 was CNS 11643 Compatibility, in reference to CNS 11643.
CJK Compatibility is a Unicode block containing square symbols encoded for compatibility with East Asian character sets. In Unicode 1.0, it was divided into two blocks, named CJK Squared Words (U+3300–U+337F) and CJK Squared Abbreviations (U+3380–U+33FF). The square forms can have different presentations when they are used in horizontal or vertical text. For example, the characters U+333E㌾SQUARE BORUTO and U+3327㌧SQUARE TON should look different in horizontal and in vertical right-to-left: ㌧㌾
Enclosed Ideographic Supplement is a Unicode block containing forms of characters and words from Chinese, Japanese and Korean enclosed within or stylised as squares, brackets, or circles. It contains three such characters containing one or more kana, and many containing CJK ideographs. Many of its characters were added for compatibility with the Japanese ARIB STD-B24 standard. Six symbols from Chinese folk religion were added in Unicode version 10.
Variation Selectors is a Unicode block containing 16 variation selectors used to specify a glyph variant for a preceding character. They are currently used to specify standardized variation sequences for mathematical symbols, emoji symbols, 'Phags-pa letters, and CJK unified ideographs corresponding to CJK compatibility ideographs. At present only standardized variation sequences with VS1–VS4, VS7, VS15 and VS16 have been defined; VS15 and VS16 are reserved to request that a character should be displayed as text or as an emoji respectively.
CJK Unified Ideographs Extension E is a Unicode block containing rare and historic CJK ideographs for Chinese, Japanese, Korean, and Vietnamese submitted to the Ideographic Research Group between 2006 and 2013, excluding the characters submitted as "urgently needed" between 2006 and 2009, which were included in CJK Unified Ideographs Extension D.
CJK Unified Ideographs Extension G is a Unicode block containing rare and historic CJK Unified Ideographs for Chinese, Japanese, Korean, and Vietnamese which were submitted to the Ideographic Research Group during 2015. It is the first block to be allocated to the Tertiary Ideographic Plane.
CJK Unified Ideographs Extension H is a Unicode block containing rare and historic CJK Unified Ideographs for Chinese, Japanese, Korean, Sawndip, and Vietnamese submitted to the Ideographic Research Group during 2017.
References
- ↑ "Unicode character database". The Unicode Standard. Retrieved 2023-07-26.
- ↑ "Enumerated Versions of The Unicode Standard". The Unicode Standard. Retrieved 2023-07-26.