Duplicate characters in Unicode: Difference between revisions

Revision as of 15:47, 15 December 2023

Revision as of 21:34, 15 January 2024

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==Duplicate vs. derived character==

{{further|characterCharacter (computing)|graphemeGrapheme}}

Unicode aims at encoding graphemes, not individual "meanings" ("semantics") of graphemes, and not [[glyph]]s.

It is a matter of case-by-case judgement whether such characters should receive separate encoding when used in technical contexts, e.g. Greek letters used as mathematical symbols: thus, the choice to have a "[[micro-]] sign" µ separate from Greek μ, but not a "[[Mega-|Mega]] sign" separate from Latin M, was a pragmatic decision by the Unicode consortium for historical reasons (namely, compatibility with [[Latin-1]], which included a micro sign). Technically µ and μ are not duplicate characters in that the consortium viewed these symbols as distinct characters (while it regarded M for "Mega" and Latin M as one and the same character).

Note that merely having different "meanings" is not sufficient grounds to split a grapheme into several characters: Thus, the [[acute accent]] may represent word accent in Welsh or Swedish, it may express vowel quality in French, and it may express vowel length in Hungarian, Icelandic or Irish. Since all these languages are written in the same [[writing system|script]], namely [[Latin script]], the acute accent in its various meanings is considered one and the same combining diacritic character (U+0301), and so the accented letter [[é]] is the same character in French and Hungarian. There is a separate "combining diacritic acute tone mark" at U+0341 for the romanization of tone languages, one important difference from the acute accent being that in a language like French, the acute accent can replace the dot over the lowercase i, whereas in a language like Vietnamese, the acute tone mark is added above the dot. Diacritic signs for alphabets considered independent may be encoded separately, such as the acute ("tonos") for the Greek alphabet at U+0384, and for the Armenian alphabet at U+055B. Some Cyrillic-based alphabets (such as [[Russian alphabet|Russian]]) also use the acute accent, but there is no "Cyrillic acute" encoded separately and U+0301 should be used for Cyrillic as well as Latin (see [[Cyrillic characters in Unicode]]). The point that the same grapheme can have many "meanings" is even more obvious considering e.g. the letter [[U]], which has entirely different phonemic referents in the various languages that use it in their orthographies (English {{IPA|/juː/, /ʊ/, /ʌ/}} etc., French {{IPA|/y/}}, German {{IPA|/uː/, /u/}}, etc., not to mention various uses of [[U (disambiguation)|U as a symbol]]).