Summary

Include schema.org accessibility metadata to enable discovery no matter how the publication is distributed or consumed.

Examples

Example 1 — Package Document metadata (EPUB 3)

The following example shows a typical set of metadata for a math textbook with MathML and described images, and that includes accessible scripted content.

<metadata>
  <meta property="schema:accessibilitySummary">
     This publication conforms to WCAG 2.0 Level AA.
  </meta>
  <meta property="schema:accessMode">textual</meta>
  <meta property="schema:accessMode">visual</meta>
  <meta property="schema:accessModeSufficent">textual,visual</meta>
  <meta property="schema:accessModeSufficent">textual</meta>
  <meta property="schema:accessibilityFeature">structuralNavigation</meta>
  <meta property="schema:accessibilityFeature">MathML</meta>
  <meta property="schema:accessibilityFeature">alternativeText</meta>
  <meta property="schema:accessibilityFeature">longDescriptions</meta>
  <meta property="schema:accessibilityAPI">ARIA</meta>
  <meta property="schema:accessibilityControl">fullKeyboardControl</meta>
  <meta property="schema:accessibilityControl">fullMouseControl</meta>
  <meta property="schema:accessibilityControl">fullTouchControl</meta>
  <meta property="schema:accessibilityHazard">noFlashing</meta>
  <meta property="schema:accessibilityHazard">noSound</meta>
  <meta property="schema:accessibilityHazard">noMotionSimulation</meta>
  …
</metadata>
Example 2 — Embedded metadata (RDFa)

Accessibility metadata that describes a single video is included within the body of an HTML document.

<div vocab="http://www.schema.org" typeof="VideoObject" property="video">
  <video controls="controls" src="croc.mp4"/>
  <meta property="accessibilityFeature" content="captions"/>
  <meta property="accessibilityFeature" content="transcript"/>
  <meta property="accessibilityControl" content="fullKeyboardControl"/>
  <meta property="accessibilityControl" content="fullMouseControl"/>
  <meta property="accessibilityControl" content="fullTouchControl"/>
  <meta property="accessibilityHazard" content="none"/>
  <p>A transcript of the video follows:</p>
  …
</div>

Explanation

The schema.org CreativeWork class includes properties defined by the Acessibility Metadata Project that can be used to identify the accessible qualities of a publication. This metadata can be expressed in HTML documents using RDFa or microdata attributes to identify the accessible qualities of the content (e.g., videos). It can also be included in the EPUB package document to provide an overall picture of the accessibility of the given rendition of the publication.

accessibilitySummary

A human-readable summary of specific accessibility features or deficiencies, consistent with the other accessibility metadata but expressing subtleties such as "short descriptions are present but long descriptions will be needed for non-visual users" or "short descriptions are present and no long descriptions are needed."

The summary is a brief, human-readable summary of features and/or deficiencies. Often used to indicate conformance to an accessibility standard or point out shortcomings to the standard.

For more detailed information on how to use this property, refer to the section Include an accessibility summary in the EPUB Accessibility Techniques.

Package Document usage:
<meta property="schema:accessibilitySummary">
   This publication conforms to the EPUB Accessibility specification 
   at WCAG Level A.
</meta>
HTML usage: (RDFa)
<p property="accessibilitySummary">
   This document conforms to WCAG 2.0 Level AA.
</p>
HTML usage: (microdata)
<p itemprop="accessibilitySummary">
   This document conforms to WCAG 2.0 Level AA.
</p>
accessMode

An access mode through which the intellectual content of a described resource or adaptation is communicated (i.e., the human sensory perceptual system or cognitive faculty through which a person may process or perceive information).

The access modes identify how content has to be consumed by default. Images and video are visual content, for example. Video clips also typically have audio, so have an auditory mode (as do audio clips). Text content is textual.

Adaptations are identified as access modes, as they are not the primary way that the content is consumed. If adaptations, such as extended descriptions, are provided for the primary content, they are used in determining the sufficient access modes.

The following values are recommended for this property:

  • auditory
  • tactile
  • textual
  • visual

For more detailed information on how to use this property, refer to the section Identify primary access modes in the EPUB Accessibility Techniques.

Package Document usage:
<meta property="schema:accessMode">textual</meta>
HTML usage: (RDFa)
<meta property="accessMode" content="textual"/>
HTML usage: (microdata)
<meta itemprop="accessMode" content="textual"/>
accessModeSufficient

A list of single or combined access modes that are sufficient to understand all the intellectual content of a resource.

Sufficient access modes identify the different combinations of senses that can be used to sufficiently consume the content. A publication with images and text will require both visual and textual modes to be consumed. If the images are also adequately described (alt text and extended descriptions, as appropriate) a single textual mode would also be sufficient, indicating someone who is blind can consume the content.

For more detailed information on how to use this property, refer to the section Identify sufficient access modes in the EPUB Accessibility Techniques.

Package Document usage:
<meta property="schema:accessModeSufficient">textual visual</meta>
<meta property="schema:accessModeSufficient">textual</meta>
HTML usage: (RDFa)
<meta property="accessModeSufficient" content="textual visual"/>
<meta property="accessModeSufficient" content="textual"/>
HTML usage: (microdata)
<meta itemprop="accessModeSufficient" content="textual visual"/>
<meta itemprop="accessModeSufficient" content="textual"/>
accessibilityFeature

Content features of the resource, such as accessible media, supported enhancements for accessibility and alternatives.

The following values are recommended for this property:

  • alternativeText
  • audioDescription
  • braille
  • captions
  • ChemML
  • displayTransformability
  • enhancedAudio
  • highContrast
  • largePrint
  • latex
  • longDescription
  • MathML
  • resizeText
  • signLanguage
  • structuralNavigation
  • tactileGraphic
  • tactileObject
  • transcript

For more detailed information on how to use this property, refer to the section Identify accessibility features in the EPUB Accessibility Techniques.

Package Document usage:
<meta property="schema:accessibilityFeature">captions</meta>
HTML usage: (RDFa)
<p>Video includes <span 
property="accessibilityFeature">captions</span>.</p>
HTML usage: (microdata)
<p>Video includes <span 
itemprop="accessibilityFeature">captions</span>.</p>
accessibilityHazard

A characteristic of the described resource that is physiologically dangerous to some users. Related to WCAG 2.0 guideline 2.3.

Identifying potential hazards in the content, such as flashing content, allows users with such sensitivities to avoid encountering the danger unwittingly.

The following values are recommended for this property:

  • flashing
  • motionSimulation
  • sound
  • none

For more detailed information on how to use this property, refer to the section Identify accessibility hazards in the EPUB Accessibility Techniques.

Package Document usage:
<meta property="schema:accessibilityHazard">flashing</meta>
HTML usage: (RDFa)
<p><strong>Warning</strong>: <span
property="accessibilityHazard">flashing</span> 
in this video may cause seizures in some 
individuals.</p>
HTML usage: (microdata)
<p><strong>Warning</strong>: <span
itemprop="accessibilityHazard">flashing</span> 
in this video may cause seizures in some 
individuals.</p>
accessibilityControl

Identifies input methods that are sufficient to control the described resource.

This property is typically only set when a publication contains scripted content that requires user interaction (i.e., whether the author has ensured that such content can be controlled by the various input methods). It is not a useful indicator for static content, and is not a guarantee that any user agent is accessible with such controls.

The following values are recommended for this property:

  • fullAudioControl
  • fullKeyboardControl
  • fullMouseControl
  • fullTouchControl
  • fullVideoControl

For more detailed information on how to use this property, refer to the section Identify Input Control Methods in the EPUB Accessibility Techniques.

Package Document usage:
<meta property="schema:accessibilityControl">fullKeyboardControl</meta>
HTML usage: (RDFa)
<meta property="accessibilityControl" content="fullKeyboardControl"/>
HTML usage: (microdata)
<meta itemprop="accessibilityControl" content="fullKeyboardControl"/>
accessibilityAPI

Indicates that the resource is compatible with the referenced accessibility API.

This property is only used when a publication has custom controls (e.g., controls created by scripting non-interactive HTML elements like img, span, div, etc.). Without ARIA roles, states and properties, these elements are not accessible to users of assistive technologies.

Native HTML controls (button, input, etc.) do not require ARIA attributes and should always be used whenever possible. If only native controls are used, this property is not applicable.

The following values are recommended for this property:

  • ARIA

For more detailed information on how to use this property, refer to the section Identify ARIA Conformance in the EPUB Accessibility Techniques.

EPUB 3 Package Document usage:
<meta property="schema:accessibilityAPI">ARIA</meta>
HTML usage: (RDFa)
<meta property="accessibilityAPI" content="ARIA"/>
HTML usage: (microdata)
<meta itemprop="accessibilityFeature" content="ARIA"/>

References