namespaces.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en-US-x-Hixie" ><head><title>2.9 Namespaces — HTML5 </title><style type="text/css">
pre { margin-left: 2em; white-space: pre-wrap; }
h2 { margin: 3em 0 1em 0; }
h3 { margin: 2.5em 0 1em 0; }
h4 { margin: 2.5em 0 0.75em 0; }
h5, h6 { margin: 2.5em 0 1em; }
h1 + h2, h1 + h2 + h2 { margin: 0.75em 0 0.75em; }
h2 + h3, h3 + h4, h4 + h5, h5 + h6 { margin-top: 0.5em; }
p { margin: 1em 0; }
hr:not(.top) { display: block; background: none; border: none; padding: 0; margin: 2em 0; height: auto; }
dl, dd { margin-top: 0; margin-bottom: 0; }
dt { margin-top: 0.75em; margin-bottom: 0.25em; clear: left; }
dt + dt { margin-top: 0; }
dd dt { margin-top: 0.25em; margin-bottom: 0; }
dd p { margin-top: 0; }
dd dl + p { margin-top: 1em; }
dd table + p { margin-top: 1em; }
p + * > li, dd li { margin: 1em 0; }
dt, dfn { font-weight: bold; font-style: normal; }
dt dfn { font-style: italic; }
pre, code { font-size: inherit; font-family: monospace; font-variant: normal; }
pre strong { color: black; font: inherit; font-weight: bold; background: yellow; }
pre em { font-weight: bolder; font-style: normal; }
@media screen { code { color: orangered; } code :link, code :visited { color: inherit; } }
var sub { vertical-align: bottom; font-size: smaller; position: relative; top: 0.1em; }
table { border-collapse: collapse; border-style: hidden hidden none hidden; }
table thead, table tbody { border-bottom: solid; }
table tbody th:first-child { border-left: solid; }
table tbody th { text-align: left; }
table td, table th { border-left: solid; border-right: solid; border-bottom: solid thin; vertical-align: top; padding: 0.2em; }
blockquote { margin: 0 0 0 2em; border: 0; padding: 0; font-style: italic; }
.bad, .bad *:not(.XXX) { color: gray; border-color: gray; background: transparent; }
.matrix, .matrix td { border: none; text-align: right; }
.matrix { margin-left: 2em; }
.dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
.dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
.dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
.toc dfn, h1 dfn, h2 dfn, h3 dfn, h4 dfn, h5 dfn, h6 dfn { font: inherit; }
img.extra { float: right; }
pre.idl { border: solid thin; background: #EEEEEE; color: black; padding: 0.5em 1em; }
pre.idl :link, pre.idl :visited { color: inherit; background: transparent; }
pre.css { border: solid thin; background: #FFFFEE; color: black; padding: 0.5em 1em; }
pre.css:first-line { color: #AAAA50; }
dl.domintro { color: green; margin: 2em 0 2em 2em; padding: 0.5em 1em; border: none; background: #DDFFDD; }
hr + dl.domintro, div.impl + dl.domintro { margin-top: 2.5em; margin-bottom: 1.5em; }
dl.domintro dt, dl.domintro dt * { color: black; text-decoration: none; }
dl.domintro dd { margin: 0.5em 0 1em 2em; padding: 0; }
dl.domintro dd p { margin: 0.5em 0; }
dl.switch { padding-left: 2em; }
dl.switch > dt { text-indent: -1.5em; }
dl.switch > dt:before { content: '\21AA'; padding: 0 0.5em 0 0; display: inline-block; width: 1em; text-align: right; line-height: 0.5em; }
dl.triple { padding: 0 0 0 1em; }
dl.triple dt, dl.triple dd { margin: 0; display: inline }
dl.triple dt:after { content: ':'; }
dl.triple dd:after { content: '\A'; white-space: pre; }
.diff-old { text-decoration: line-through; color: silver; background: transparent; }
.diff-chg, .diff-new { text-decoration: underline; color: green; background: transparent; }
a .diff-new { border-bottom: 1px blue solid; }
h2 { page-break-before: always; }
h1, h2, h3, h4, h5, h6 { page-break-after: avoid; }
h1 + h2, hr + h2.no-toc { page-break-before: auto; }
p > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]),
li > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]), { border-bottom: solid #9999CC; }
div.head { margin: 0 0 1em; padding: 1em 0 0 0; }
div.head p { margin: 0; }
div.head h1 { margin: 0; }
div.head .logo { float: right; margin: 0 1em; }
div.head .logo img { border: none } /* remove border from top image */
div.head dl { margin: 1em 0; }
div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
body > .toc > li { margin-top: 1em; margin-bottom: 1em; }
body > .toc.brief > li { margin-top: 0.35em; margin-bottom: 0.35em; }
body > .toc > li > * { margin-bottom: 0.5em; }
body > .toc > li > * > li > * { margin-bottom: 0.25em; }
.toc, .toc li { list-style: none; }
.brief { margin-top: 1em; margin-bottom: 1em; line-height: 1.1; }
.brief li { margin: 0; padding: 0; }
.brief li p { margin: 0; padding: 0; }
.category-list { margin-top: -0.75em; margin-bottom: 1em; line-height: 1.5; }
.category-list::before { content: '\21D2\A0'; font-size: 1.2em; font-weight: 900; }
.category-list li { display: inline; }
.category-list li:not(:last-child)::after { content: ', '; }
.category-list li > span, .category-list li > a { text-transform: lowercase; }
.category-list li * { text-transform: none; } /* don't affect <code> nested in <a> */
.XXX { color: #E50000; background: white; border: solid red; padding: 0.5em; margin: 1em 0; }
.XXX > :first-child { margin-top: 0; }
p .XXX { line-height: 3em; }
.annotation { border: solid thin black; background: #0C479D; color: white; position: relative; margin: 8px 0 20px 0; }
.annotation:before { position: absolute; left: 0; top: 0; width: 100%; height: 100%; margin: 6px -6px -6px 6px; background: #333333; z-index: -1; content: ''; }
.annotation :link, .annotation :visited { color: inherit; }
.annotation :link:hover, .annotation :visited:hover { background: transparent; }
.annotation span { border: none ! important; }
.note { color: green; background: transparent; font-family: sans-serif; }
.warning { color: red; background: transparent; }
.note, .warning { font-weight: bolder; font-style: italic; }
p.note, div.note { padding: 0.5em 2em; }
span.note { padding: 0 2em; }
.note p:first-child, .warning p:first-child { margin-top: 0; }
.note p:last-child, .warning p:last-child { margin-bottom: 0; }
.warning:before { font-style: normal; }
p.note:before { content: 'Note: '; }
p.warning:before { content: '\26A0 Warning! '; }
.bookkeeping:before { display: block; content: 'Bookkeeping details'; font-weight: bolder; font-style: italic; }
.bookkeeping { font-size: 0.8em; margin: 2em 0; }
.bookkeeping p { margin: 0.5em 2em; display: list-item; list-style: square; }
.bookkeeping dt { margin: 0.5em 2em 0; }
.bookkeeping dd { margin: 0 3em 0.5em; }
h4 { position: relative; z-index: 3; }
h4 + .element, h4 + div + .element { margin-top: -2.5em; padding-top: 2em; }
.element {
background: #EEEEFF;
color: black;
margin: 0 0 1em 0.15em;
padding: 0 1em 0.25em 0.75em;
border-left: solid #9999FF 0.25em;
position: relative;
z-index: 1;
}
.element:before {
position: absolute;
z-index: 2;
top: 0;
left: -1.15em;
height: 2em;
width: 0.9em;
background: #EEEEFF;
content: ' ';
border-style: none none solid solid;
border-color: #9999FF;
border-width: 0.25em;
}
.example { display: block; color: #222222; background: #FCFCFC; border-left: double; margin-left: 2em; padding-left: 1em; }
td > .example:only-child { margin: 0 0 0 0.1em; }
ul.domTree, ul.domTree ul { padding: 0 0 0 1em; margin: 0; }
ul.domTree li { padding: 0; margin: 0; list-style: none; position: relative; }
ul.domTree li li { list-style: none; }
ul.domTree li:first-child::before { position: absolute; top: 0; height: 0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
ul.domTree li:not(:last-child)::after { position: absolute; top: 0; bottom: -0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
ul.domTree span { font-style: italic; font-family: serif; }
ul.domTree .t1 code { color: purple; font-weight: bold; }
ul.domTree .t2 { font-style: normal; font-family: monospace; }
ul.domTree .t2 .name { color: black; font-weight: bold; }
ul.domTree .t2 .value { color: blue; font-weight: normal; }
ul.domTree .t3 code, .domTree .t4 code, .domTree .t5 code { color: gray; }
ul.domTree .t7 code, .domTree .t8 code { color: green; }
ul.domTree .t10 code { color: teal; }
body.dfnEnabled dfn { cursor: pointer; }
.dfnPanel {
display: inline;
position: absolute;
z-index: 10;
height: auto;
width: auto;
padding: 0.5em 0.75em;
font: small sans-serif, Droid Sans Fallback;
background: #DDDDDD;
color: black;
border: outset 0.2em;
}
.dfnPanel * { margin: 0; padding: 0; font: inherit; text-indent: 0; }
.dfnPanel :link, .dfnPanel :visited { color: black; }
.dfnPanel p { font-weight: bolder; }
.dfnPanel * + p { margin-top: 0.25em; }
.dfnPanel li { list-style-position: inside; }
#configUI { position: absolute; z-index: 20; top: 10em; right: 1em; width: 11em; font-size: small; }
#configUI p { margin: 0.5em 0; padding: 0.3em; background: #EEEEEE; color: black; border: inset thin; }
#configUI p label { display: block; }
#configUI #updateUI, #configUI .loginUI { text-align: center; }
#configUI input[type=button] { display: block; margin: auto; }
fieldset { margin: 1em; padding: 0.5em 1em; }
fieldset > legend + * { margin-top: 0; }
fieldset > :last-child { margin-bottom: 0; }
fieldset p { margin: 0.5em 0; }
.stability {
position: fixed;
bottom: 0;
left: 0; right: 0;
margin: 0 auto 0 auto !important;
z-index: 1000;
width: 50%;
background: maroon; color: yellow;
-webkit-border-radius: 1em 1em 0 0;
-moz-border-radius: 1em 1em 0 0;
border-radius: 1em 1em 0 0;
-moz-box-shadow: 0 0 1em #500;
-webkit-box-shadow: 0 0 1em #500;
box-shadow: 0 0 1em red;
padding: 0.5em 1em;
text-align: center;
}
.stability strong {
display: block;
}
.stability input {
appearance: none; margin: 0; border: 0; padding: 0.25em 0.5em; background: transparent; color: black;
position: absolute; top: -0.5em; right: 0; font: 1.25em sans-serif; text-align: center;
}
.stability input:hover {
color: white;
text-shadow: 0 0 2px black;
}
.stability input:active {
padding: 0.3em 0.45em 0.2em 0.55em;
}
.stability :link, .stability :visited,
.stability :link:hover, .stability :visited:hover {
background: transparent;
color: white;
}
</style><link href="data:text/css,.impl%20%7B%20display:%20none;%20%7D%0Ahtml%20%7B%20border:%20solid%20yellow;%20%7D%20.domintro:before%20%7B%20display:%20none;%20%7D" id="author" rel="alternate stylesheet" title="Author documentation only"><link href="data:text/css,.impl%20%7B%20background:%20%23FFEEEE;%20%7D%20.domintro:before%20%7B%20background:%20%23FFEEEE;%20%7D" id="highlight" rel="alternate stylesheet" title="Highlight implementation
requirements"><link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css"><style type="text/css">
.applies thead th > * { display: block; }
.applies thead code { display: block; }
.applies tbody th { whitespace: nowrap; }
.applies td { text-align: center; }
.applies .yes { background: yellow; }
.matrix, .matrix td { border: hidden; text-align: right; }
.matrix { margin-left: 2em; }
.dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
.dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
.dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
td.eg { border-width: thin; text-align: center; }
#table-example-1 { border: solid thin; border-collapse: collapse; margin-left: 3em; }
#table-example-1 * { font-family: "Essays1743", serif; line-height: 1.01em; }
#table-example-1 caption { padding-bottom: 0.5em; }
#table-example-1 thead, #table-example-1 tbody { border: none; }
#table-example-1 th, #table-example-1 td { border: solid thin; }
#table-example-1 th { font-weight: normal; }
#table-example-1 td { border-style: none solid; vertical-align: top; }
#table-example-1 th { padding: 0.5em; vertical-align: middle; text-align: center; }
#table-example-1 tbody tr:first-child td { padding-top: 0.5em; }
#table-example-1 tbody tr:last-child td { padding-bottom: 1.5em; }
#table-example-1 tbody td:first-child { padding-left: 2.5em; padding-right: 0; width: 9em; }
#table-example-1 tbody td:first-child::after { content: leader(". "); }
#table-example-1 tbody td { padding-left: 2em; padding-right: 2em; }
#table-example-1 tbody td:first-child + td { width: 10em; }
#table-example-1 tbody td:first-child + td ~ td { width: 2.5em; }
#table-example-1 tbody td:first-child + td + td + td ~ td { width: 1.25em; }
.apple-table-examples { border: none; border-collapse: separate; border-spacing: 1.5em 0em; width: 40em; margin-left: 3em; }
.apple-table-examples * { font-family: "Times", serif; }
.apple-table-examples td, .apple-table-examples th { border: none; white-space: nowrap; padding-top: 0; padding-bottom: 0; }
.apple-table-examples tbody th:first-child { border-left: none; width: 100%; }
.apple-table-examples thead th:first-child ~ th { font-size: smaller; font-weight: bolder; border-bottom: solid 2px; text-align: center; }
.apple-table-examples tbody th::after, .apple-table-examples tfoot th::after { content: leader(". ") }
.apple-table-examples tbody th, .apple-table-examples tfoot th { font: inherit; text-align: left; }
.apple-table-examples td { text-align: right; vertical-align: top; }
.apple-table-examples.e1 tbody tr:last-child td { border-bottom: solid 1px; }
.apple-table-examples.e1 tbody + tbody tr:last-child td { border-bottom: double 3px; }
.apple-table-examples.e2 th[scope=row] { padding-left: 1em; }
.apple-table-examples sup { line-height: 0; }
.details-example img { vertical-align: top; }
#base64-table {
white-space: nowrap;
font-size: 0.6em;
column-width: 6em;
column-count: 5;
column-gap: 1em;
-moz-column-width: 6em;
-moz-column-count: 5;
-moz-column-gap: 1em;
-webkit-column-width: 6em;
-webkit-column-count: 5;
-webkit-column-gap: 1em;
}
#base64-table thead { display: none; }
#base64-table * { border: none; }
#base64-table tbody td:first-child:after { content: ':'; }
#base64-table tbody td:last-child { text-align: right; }
#named-character-references-table {
white-space: nowrap;
font-size: 0.6em;
column-width: 30em;
column-gap: 1em;
-moz-column-width: 30em;
-moz-column-gap: 1em;
-webkit-column-width: 30em;
-webkit-column-gap: 1em;
}
#named-character-references-table > table > tbody > tr > td:first-child + td,
#named-character-references-table > table > tbody > tr > td:last-child { text-align: center; }
#named-character-references-table > table > tbody > tr > td:last-child:hover > span { position: absolute; top: auto; left: auto; margin-left: 0.5em; line-height: 1.2; font-size: 5em; border: outset; padding: 0.25em 0.5em; background: white; width: 1.25em; height: auto; text-align: center; }
#named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
.glyph.control { color: red; }
@font-face {
font-family: 'Essays1743';
src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743.ttf');
}
@font-face {
font-family: 'Essays1743';
font-weight: bold;
src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Bold.ttf');
}
@font-face {
font-family: 'Essays1743';
font-style: italic;
src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-Italic.ttf');
}
@font-face {
font-family: 'Essays1743';
font-style: italic;
font-weight: bold;
src: url('http://www.whatwg.org/specs/web-apps/current-work/fonts/Essays1743-BoldItalic.ttf');
}
</style><style type="text/css">
.domintro:before { display: table; margin: -1em -0.5em -0.5em auto; width: auto; content: 'This box is non-normative. Implementation requirements are given below this box.'; color: black; font-style: italic; border: solid 2px; background: white; padding: 0 0.25em; }
</style><script type="text/javascript">
function getCookie(name) {
var params = location.search.substr(1).split("&");
for (var index = 0; index < params.length; index++) {
if (params[index] == name)
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if (data[0] == name)
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return null;
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</script>
<script src="link-fixup.js" type="text/javascript"></script>
<link href="style.css" rel="stylesheet"><link href="common-dom-interfaces.html" title="2.8 Common DOM interfaces" rel="prev">
<link href="spec.html#contents" title="Table of contents" rel="index">
<link href="dom.html" title="3 Semantics, structure, and APIs of HTML documents" rel="next">
</head><body><div class="head" id="head">
<div id="multipage-common">
<p class="stability" id="wip"><strong>This is a work in
progress!</strong> For the latest updates from the HTML WG, possibly
including important bug fixes, please look at the <a href="http://dev.w3.org/html5/spec/Overview.html">editor's draft</a> instead.
There may also be a more
<a href="http://www.w3.org/TR/html5">up-to-date Working Draft</a>
with changes based on resolution of Last Call issues.
<input onclick="closeWarning(this.parentNode)" type="button" value="╳⃝"></p>
<script type="text/javascript">
function closeWarning(element) {
element.parentNode.removeChild(element);
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<p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
<h1>HTML5</h1>
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<a href="spec.html#contents">Table of contents</a> –
<a href="dom.html" class="next">3 Semantics, structure, and APIs of HTML documents</a>
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<h3 id="namespaces"><span class="secno">2.9 </span>Namespaces</h3><p>The <dfn id="html-namespace-0">HTML namespace</dfn> is: <code>http://www.w3.org/1999/xhtml</code></p><p>The <dfn id="mathml-namespace">MathML namespace</dfn> is: <code>http://www.w3.org/1998/Math/MathML</code></p><p>The <dfn id="svg-namespace">SVG namespace</dfn> is: <code>http://www.w3.org/2000/svg</code></p><p>The <dfn id="xlink-namespace">XLink namespace</dfn> is: <code>http://www.w3.org/1999/xlink</code></p><p>The <dfn id="xml-namespace">XML namespace</dfn> is: <code>http://www.w3.org/XML/1998/namespace</code></p><p>The <dfn id="xmlns-namespace">XMLNS namespace</dfn> is: <code>http://www.w3.org/2000/xmlns/</code></p><hr><p>Data mining tools and other user agents that perform operations
on content without running scripts, evaluating CSS or XPath
expressions, or otherwise exposing the resulting DOM to arbitrary
content, may "support namespaces" by just asserting that their DOM
node analogues are in certain namespaces, without actually exposing
the above strings.</p><hr><p class="note">In <a href="syntax.html#syntax">the HTML syntax</a>, namespace prefixes
and namespace declarations do not have the same effect as in XML.
For instance, the colon has no special meaning in HTML element
names.</p></body></html>