About this specification

This specification is like no other — it has been processed with you, the humble web developer, in mind.

The focus of this specification is readability and ease of access. Unlike the full HTML Standard, this "developer's edition" removes information that only browser vendors need know. It is automatically produced from the full specification by our build tooling, and thus always in sync with the latest developments in HTML.

To read about its conception, construction, and future, read the original press release, and the blog post about its relaunch.

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      1. 4.8.16 MathML
      2. 4.8.17 SVG
      3. 4.8.18 Dimension attributes

4.8.16 MathML

Support: mathmlChrome (removed) -24iOS Safari 5.0+UC Browser for Android (limited) 11.4+Firefox 2+IE NoneSafari 10+Opera (removed) -12.1Edge None

Source: caniuse.com

The MathML math element falls into the embedded content, phrasing content, flow content, and palpable content categories for the purposes of the content models in this specification.

When the MathML annotation-xml element contains elements from the HTML namespace, such elements must all be flow content.

When the MathML token elements (mi, mo, mn, ms, and mtext) are descendants of HTML elements, they may contain phrasing content elements from the HTML namespace.

The semantics of MathML elements are defined by the MathML specification and other applicable specifications. [MATHML]

Here is an example of the use of MathML in an HTML document:

<!DOCTYPE html>
<html lang="en">
 <head>
  <title>The quadratic formula</title>
 </head>
 <body>
  <h1>The quadratic formula</h1>
  <p>
   <math>
    <mi>x</mi>
    <mo>=</mo>
    <mfrac>
     <mrow>
      <mo form="prefix">−</mo> <mi>b</mi>
      <mo>±</mo>
      <msqrt>
       <msup> <mi>b</mi> <mn>2</mn> </msup>
       <mo>−</mo>
       <mn>4</mn> <mo>⁢</mo> <mi>a</mi> <mo>⁢</mo> <mi>c</mi>
      </msqrt>
     </mrow>
     <mrow>
      <mn>2</mn> <mo>⁢</mo> <mi>a</mi>
     </mrow>
    </mfrac>
   </math>
  </p>
 </body>
</html>

4.8.17 SVG

Support: svg-html5Chrome for Android 61+Chrome 7+iOS Safari 5.0+UC Browser for Android 11.4+Firefox 4+IE 9+Samsung Internet 4+Opera Mini all+Safari 5.1+Android Browser 3+Opera 11.6+Edge 12+

Source: caniuse.com

The SVG svg element falls into the embedded content, phrasing content, flow content, and palpable content categories for the purposes of the content models in this specification.

When the SVG foreignObject element contains elements from the HTML namespace, such elements must all be flow content.

The content model for the SVG title element inside HTML documents is phrasing content. (This further constrains the requirements given in the SVG specification.)

The semantics of SVG elements are defined by the SVG specification and other applicable specifications. [SVG]


doc = iframe . getSVGDocument()
doc = embed . getSVGDocument()
doc = object . getSVGDocument()

Returns the Document object, in the case of iframe, embed, or object elements being used to embed SVG images.

4.8.18 Dimension attributes

The width and height attributes on img, iframe, embed, object, video, and, when their type attribute is in the Image Button state, input elements may be specified to give the dimensions of the visual content of the element (the width and height respectively, relative to the nominal direction of the output medium), in CSS pixels. The attributes, if specified, must have values that are valid non-negative integers.

The specified dimensions given may differ from the dimensions specified in the resource itself, since the resource may have a resolution that differs from the CSS pixel resolution. (On screens, CSS pixels have a resolution of 96ppi, but in general the CSS pixel resolution depends on the reading distance.) If both attributes are specified, then one of the following statements must be true:

The target ratio is the ratio of the intrinsic width to the intrinsic height in the resource. The specified width and specified height are the values of the width and height attributes respectively.

The two attributes must be omitted if the resource in question does not have both an intrinsic width and an intrinsic height.

If the two attributes are both zero, it indicates that the element is not intended for the user (e.g. it might be a part of a service to count page views).

The dimension attributes are not intended to be used to stretch the image.