Unicode: Difference between revisions

Revision as of 17:33, 9 August 2025

Revision as of 04:19, 13 August 2025

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''The Unicode Standard'' defines a ''codespace'':<ref name="Glossary">{{Cite web |title=Glossary of Unicode Terms |url=https://unicode.org/glossary/ |access-date=16 March 2010}}</ref> a sequence of integers called ''[[code point]]s''<ref name=":0">{{Cite book |url=https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-2/#G25564 |title=The Unicode Standard Version 16.0 – Core Specification |year=2024 |chapter=2.4 Code Points and Characters}}</ref> in the range from 0 to {{val|1114111}}, notated according to the standard as {{tt|U+0000}}–{{tt|U+10FFFF}}.<ref>{{Cite book |url=https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-3/#G2212 |title=The Unicode Standard, Version 16.0 |year=2024 |chapter=3.4 Characters and Encoding}}</ref> The codespace is a systematic, architecture-independent representation of ''The Unicode Standard''; actual text is processed as binary data via one of several Unicode encodings, such as [[UTF-8]].

In this normative notation, the two-character prefix <code>U+</code> always precedes a written code point, and the code points themselves are written as [[hexadecimal]] numbers.{{Refn|The two-character prefix <code>U+</code> was chosen as an ASCII approximation of {{unichar|U+228E}}, always precedes a written code point,.<ref>{{Cite mailing list |url=https://unicode.org/mail-arch/unicode-ml/y2005-m11/0060.html |title=Re: Origin of the U+nnnn notation |date=8 November 2005 |mailing-list=Unicode Mail List Archive}}</ref> and the code points themselves are written as [[hexadecimal]] numbers.|group=note}} At least four hexadecimal digits are always written, with [[leading zero]]s prepended as needed. For example, the code point {{unichar|F7|Division sign}} is padded with two leading zeros, but {{unichar|13254|Egyptian hieroglyph O004}} ([[File:Hiero O4.png|class=skin-invert-image|text-bottom|15px]]) is not padded.<ref>{{Cite web |date=September 2024 |title=Appendix A: Notational Conventions |url=https://www.unicode.org/versions/Unicode16.0.0/core-spec/appendix-a/ |website=The Unicode Standard |publisher=Unicode Consortium}}</ref>

There are a total of {{val|1112064}} valid code points within the codespace.<ref>{{cite book |title=The Unicode Standard |publisher=[[The Unicode Consortium]] |isbn=978-1-936213-01-6 |edition=6.0 |___location=Mountain View, California, US |at=3.9 Unicode Encoding Forms |chapter=Conformance |quote=Each encoding form maps the Unicode code points U+0000..U+D7FF and U+E000..U+10FFFF |chapter-url=https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-3/#G7404}}</ref> This number arises from the limitations of the [[UTF-16]] character encoding, which can encode the 2¹⁶ code points in the range {{tt|U+0000}} through {{tt|U+FFFF}} except for the 2¹¹ code points in the range {{tt|U+D800}} through {{tt|U+DFFF}}, which are used as surrogate pairs to encode the 2²⁰ code points in the range {{tt|U+10000}} through {{tt|U+10FFFF}}.