<html xmlns="http://www.w3.org/1999/xhtml"><head></head><body><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="8" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[8]</anchor-end> <dfn><rubyb xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:"><anchor>符号化ラベル</anchor><rt xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">encoding label</rt></rubyb></dfn>は、
<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">文字符号化</anchor>を<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">識別</anchor>する短い<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">文字列</anchor>です。<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">文字符号化</anchor>ごとにいくつか定められています。</p><section><h1>仕様書</h1><refs xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:"><ul xmlns="http://www.w3.org/1999/xhtml"><li><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="6" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[6]</anchor-end> <cite xml:lang="en-US">Encoding Standard</cite> (<time>2016-07-29 16:12:31 +09:00</time>) <anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://encoding.spec.whatwg.org/#label">https://encoding.spec.whatwg.org/#label</anchor-external></li></ul></refs></section><section><h1>意味</h1><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="7" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[7]</anchor-end> <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化<title xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:10:">文字符号化</title></anchor>は、1つ<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">以上</anchor>の<dfn><rubyb xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">ラベル<rt xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">label</rt></rubyb></dfn>を持ちます <src xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:10:"><anchor-internal xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="6" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">&gt;&gt;6</anchor-internal></src>。</p></section><section><h1>演算</h1><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="16" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[16]</anchor-end> <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化の取得</anchor>により、<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化ラベル</anchor>から<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">文字符号化</anchor>を得ることができます。</p></section><section><h1>文脈</h1><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="2" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[2]</anchor-end> 次の場面で使うことができます。</p><figure class="list short"><figcaption><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="17" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[17]</anchor-end> <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化ラベル</anchor>を使う場面</figcaption><ul><li><anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:"><code xmlns="http://www.w3.org/1999/xhtml">charset</code>引数</anchor></li><li><code class="HTML" xml:lang="en">&lt;meta charset&gt;</code></li><li><code class="HTML" xml:lang="en">&lt;meta http-equiv=Content-Type&gt;</code></li><li><code class="HTML" xml:lang="en"><anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">&lt;script charset&gt;</anchor></code></li></ul></figure></section><section><h1>関連</h1><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="4" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[4]</anchor-end> <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化名</anchor>は、 <del><anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">replacement</anchor> を除き、</del> すべて<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化ラベル</anchor>でもあります。</p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="3" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[3]</anchor-end> <code class="HTML" xml:lang="en"><anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">&lt;script charset&gt;</anchor></code> では、 <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">Content-Typeメタデータ</anchor>の
<f xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:"><code xmlns="http://www.w3.org/1999/xhtml" class="MIME" xml:lang="en"><anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">charset</anchor></code></f> の値と同じ<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">文字符号化</anchor>を表さなければならないとの制約があります。</p><comment-p xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:10:"><code xmlns="http://www.w3.org/1999/xhtml" class="HTML" xml:lang="en"><anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">&lt;script charset&gt;</anchor></code> 参照。</comment-p><section><h1>IANA charset との関係</h1><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="9" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[9]</anchor-end> <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化ラベル</anchor>は、 <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">IANA charset</anchor> から派生したものですが、
長い <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">Web</anchor> の歴史において色々な原因で増えたバリエーションを収録し、
<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">Web</anchor> で使われないものや<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">セキュリティー</anchor>上問題があるものを除去することで、
成立しました。</p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="10" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[10]</anchor-end> 従って、<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">IANA charset</anchor> と似ていますが、包含関係はありません。
同じ<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">識別子</anchor>であっても、 <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">符号化ラベル</anchor>と解釈する場合と <anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">IANA charset</anchor>
と解釈する場合とで、異なる<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">文字コード</anchor>を表すことも少なくありません。</p></section></section><section><h1>歴史</h1><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="1" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[1]</anchor-end> <cite xml:lang="en">Fix #32: use the encoding name exposed by DOM and HTML &lt;form&gt; · whatwg/encoding@18bf4fa</cite>
(<time>2016-02-11 11:49:10 +09:00</time> 版)
<anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://github.com/whatwg/encoding/commit/18bf4fa6f005a899696800a8f6b0d20f3a4c1c0e">https://github.com/whatwg/encoding/commit/18bf4fa6f005a899696800a8f6b0d20f3a4c1c0e</anchor-external></p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="5" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[5]</anchor-end> <cite xml:lang="en">Regression: do not use &quot;get an output encoding&quot; for decoding · whatwg/html@c36f738</cite>
(<time>2016-04-26 20:52:13 +09:00</time> 版)
<anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://github.com/whatwg/html/commit/c36f7384f1f617b13c68d28b89d850cb18ceadfb">https://github.com/whatwg/html/commit/c36f7384f1f617b13c68d28b89d850cb18ceadfb</anchor-external></p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="11" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[11]</anchor-end> <cite xml:lang="en">Add &quot;replacement&quot; as label for the replacement encoding by annevk · Pull Request #117 · whatwg/encoding</cite>
(<time>2017-08-19 20:57:16 +09:00</time>)
<anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://github.com/whatwg/encoding/pull/117">https://github.com/whatwg/encoding/pull/117</anchor-external></p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="12" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[12]</anchor-end> <cite xml:lang="en">Add &quot;replacement&quot; as a label for the replacement encoding · Issue #70 · whatwg/encoding</cite>
(<time>2017-08-19 21:03:28 +09:00</time>)
<anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://github.com/whatwg/encoding/issues/70">https://github.com/whatwg/encoding/issues/70</anchor-external></p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="13" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[13]</anchor-end> <cite xml:lang="en"><strong>[</strong>acgiow<strong>]</strong> (2) Make encoding name normalisation part of the spec. ASCII…</cite>
(<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">Hixie</anchor>著, <time>2008-05-23 07:15:00 +09:00</time>)
<anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://github.com/whatwg/html/commit/fc1bb8fe3afa6af5a2d8e3af0df9153c43a40eab">https://github.com/whatwg/html/commit/fc1bb8fe3afa6af5a2d8e3af0df9153c43a40eab</anchor-external></p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="14" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[14]</anchor-end> <cite xml:lang="en">Let the Encoding Standard deal with the canonical name</cite>
(<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">annevk</anchor>著, <time>2016-02-10 23:23:57 +09:00</time>)
<anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://github.com/whatwg/dom/commit/2bf4e6273af4da39113dc27fa23dbd447329ec31">https://github.com/whatwg/dom/commit/2bf4e6273af4da39113dc27fa23dbd447329ec31</anchor-external></p><p><anchor-end xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:anchor="15" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:">[15]</anchor-end> <cite xml:lang="en">Fix #32: use the encoding name exposed by DOM and HTML &lt;form&gt;</cite>
(<anchor xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:">annevk</anchor>著, <time>2016-02-10 23:20:18 +09:00</time>)
<anchor-external xmlns="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resScheme="URI" xmlns:a0="urn:x-suika-fam-cx:markup:suikawiki:0:9:" a0:resParameter="https://github.com/whatwg/encoding/commit/18bf4fa6f005a899696800a8f6b0d20f3a4c1c0e">https://github.com/whatwg/encoding/commit/18bf4fa6f005a899696800a8f6b0d20f3a4c1c0e</anchor-external></p></section></body></html>