WebSchemas/Accessibility

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This is a WebSchemas proposal Accessibility schema for schema.org. See Proposals listing for more. Status: Proposal



Overview

Making Accessible Content Discoverable

The A11yMetadata Project seeks to extend schema.org by including new properties to address the accessibility and discoverability of resources on the Web.

A majority of properties and terms in this proposal are a subset derived from the IMS Global Learning Consortium's Access For All specification. IMS Global Learning Consortium has licensed these properties to schema.org under the Creative Commons Attribute-ShareAlike License (version 3.0) so that they can be used under schema.org‘s corresponding terms and conditions. Any other organizations or initiatives that would like to adopt IMS Global’s AccessForAll for other purposes are requested to coordinate directly with IMS Global.

V.5 was submitted on April 15, 2013

V.6 was finalized on September 8, 2013. The major changes are simplifications: moving displayTransformability from a property to a property value of mediaFeature, adding a few more mediaFeature properties, reordering some items and making clear that two properties are only for use on softwareApplication and its subclasses. This simplicity does not detract from the information model, but eases adoption. The two samples were also updated to reflect these changes. V.6 was never fully publicized, but became a working model for the group.

Changes are being made for a .7 specification, which is expected to be published on November 8, 2013. There was a significant amount of work that went into this, but the net is minor changes and simplifications through the extensions mechanism and much better descriptions, There are a number of refinements to the properties, simplifying some with the use of extensions, adding new property values and renaming some of the properties to new names. While most of these are simple refinements in definition or name changes, some of the these name changes will impact all existing tagged documents. The most significant of these is to change mediaFeature to accessFeature and controlFlexibility to accessFlexibility. Details of these changes can be sen in the minutes of the working group in October and November 2013. We also changed the sense of values in accessHazard to allow both negative and positive assertions. This addresses issues 1, 2 and 3, as well as 8.

There is now an Open Issues wiki page that will track issues as we drive to completion. Open items will be noted on this page, and the tracker will contain them all.

Vocabulary

(Definitions for most of the expected values can be found in the IMS Global Access for All (AfA) Information Model Data Element Specification.)

Current Proposal

Property Expected Type Expected Values Description
accessFeature Text
  • alternativeText
  • audioDescription
  • braille
  • captions
  • ChemML
  • displayTransformability
  • enhancedAudio
  • highContrast
  • largePrint
  • latex
  • longDescription
  • MathML
  • resizeText
  • signLanguage
  • structuralNavigation
  • tactileGraphic
  • tactileObject
  • transcript
Content features of the resource, such as accessible media, supported enhancements for accessibility and alternatives. See the AccessFeature in more depth explanation for more detail on the three different types of access features available.
accessHazard Text
  • flashing (deprecated)
  • noFlashing
  • motionSimulation (deprecated)
  • noMotionSimulation
  • sound (deprecated)
  • noSound
A characteristic of the described resource that is physiologically dangerous to some users. This is related to WCAG 2.0 guideline 2.3. All three of the negative properties should be set if there are none of the hazards known to date. If no properties are set, the state of accessHazards is unknown, rather than no hazard.
accessAPI Text
  • AndroidAccessibility
  • ARIA
  • ATK
  • AT-SPI
  • BlackberryAccessibility
  • iAccessible2
  • iOSAccessibility
  • JavaAccessibility
  • MacOSXAccessibility
  • MSAA
  • UIAutomation
Indicates that the resource is compatible with the referenced accessibility API.
accessFlexibility - (discussion about the name, to avoid clashing with Access Control Systems) Text
  • fullAudioControl
  • fullKeyboardControl
  • fullMouseControl
  • fullTouchControl
  • fullVideoControl
  • timing
Identifies one or more input methods can be used that allow access to all of the application functionality.

The "full" proposal

@@This needs to be annotated to explain what's happening. See also the Issues page.

Property Expected Type Expected Values Description
accessMode Text
  • auditory
  • tactile
  • textual
  • visual
  • colorDependent
  • chartOnVisual
  • chemOnVisual
  • diagramOnVisual
  • mathOnVisual
  • musicOnVisual
  • textOnVisual
An access mode through which the intellectual content of a described resource or adaptation is communicated. The IMS model defines this as "The human sensory perceptual system or cognitive faculty through which a person may process or perceive information." If adaptations for the resource are known, the access modes of those adaptations are not included. The accessModes after visual in the list are all refinements of what is presented in the visual mode.
accessFeature Text
  • alternativeText
  • audioDescription
  • braille
  • captions
  • ChemML
  • displayTransformability
  • enhancedAudio
  • highContrast
  • largePrint
  • latex
  • longDescription
  • MathML
  • resizeText
  • signLanguage
  • structuralNavigation
  • tactileGraphic
  • tactileObject
  • transcript
Content features of the resource, such as accessible media, supported enhancements for accessibility and alternatives. See the AccessFeature in more depth explanation for more detail on the three different types of access features available.
hasAdaptation URL Identifier of a resource that is an adaptation, for accessibility purposes, for this resource.
isAdaptationOf URL Identifier of a resource for which this is an adaptation for accessibility purposes.
accessHazard Text
  • flashing
  • noFlashing
  • motionSimulation
  • noMotionSimulation
  • sound
  • noSound
A characteristic of the described resource that is physiologically dangerous to some users. This is related to WCAG 2.0 guideline 2.3. All three of the negative properties should be set if there are none of the hazards known to date. If no properties are set, the state of accessHazards is unknown, rather than no hazard.
ATCompatible Boolean The resource is compatible with assistive technologies. For example, that the resource complies to WCAG 2.0 checkpoints: 1.1.1, 1.3.1, 1.3.2, 2.4.4, 3.1.1, 3.1.2, 3.3.2, 4.1.1, 4.1.2.
accessAPI Text
  • AndroidAccessibility
  • ARIA
  • ATK
  • AT-SPI
  • BlackberryAccessibility
  • iAccessible2
  • iOSAccessibility
  • JavaAccessibility
  • MacOSXAccessibility
  • MSAA
  • UIAutomation
Indicates that the resource is compatible with the referenced accessibility API.
accessFlexibility Text
  • fullAudioControl
  • fullKeyboardControl
  • fullMouseControl
  • fullTouchControl
  • fullVideoControl
  • timing
Identifies one or more input methods can be used that allow access to all of the application functionality.

Use of extensions on bookFormat

The current use of bookFormat uses an enumeration for the type, but it only goes one level deep (EBook, Hardcover, Paperback)

This proposal also requests the expansion of bookFormat to include the following extensions of EBook and Paperback:

  • EBook/DAISY202
  • Ebook/DAISY3
  • Ebook/Mp3
  • Ebook/EPUB2
  • EBook/EPUB3
  • Ebook/BRF
  • EBook/PDF and other formats, mobi, etc.
  • Paperback/Braille

AccessFeature in more depth

The property accessFeature has multiple property values. Each of these is worth a short description. First, there are three types of accessFeatures: transform, structure and augmentation.

  • Transform acccessFeatures are transformations of or enhancements to content that make it more accessible without changing the access mode. A large print book is a good example of this.
  • Structure accessFeatures describe the access aids that are provided to work within the media, such as the use of a table of contents, index or other items to be able to navigate to a point in content easily without linear scanning.
  • Augmentation accessFeatures make the content in one accessMode available in a different one. The augmentation type that most people are familiar with is alternativeText, which people have learned to apply to HTML images. While transform and structure accessFeatures do not require intelligence to apply, an augmentation normally will. As such, their quality cannot always be counted on.

There are three tables below, one for each of the types of accessFeatures. The extensions that can be used are unique to each of the types.


AccessFeature for transformation

Transform accessFeatures either state how content is available in a transformed state or is set up so that a user can transform it. These properties derive from WCAG 2.0 section 1.4 and surrounding areas. Common refinement/extensions of the property value are

  • /nnn (a specific pointsize, common for large print)
  • /CSSEnabled - that the resource has been designed to be mutable through CSS in an appropriate viewer
  • /yellowOnBlack or other specific common color combinations (for high contrast)


Expected Values Transformed Access Mode Description
  • highContrast
Visual, Textual can add most comment colors as extensions, such as highContrast/yellowOnBlack, greenOnBlack, whiteOnBlack and blackOnWhite or just say /CSSEnabled if CSS is set up to allow these changes to be customized by the user.
  • largePrint
Visual, Textual can add specific pointsize, as in largePrint/18 or just /CSSEnabled. Printed books (Visual) would never use the /CSSEnabled: that would be limited to electronic texts. A physical book would, if any extension, use a pointsize.
  • resizeText
Textual either /CSSEnabled or the extension /taggedPDF if the PDF allows resize and reflow.
  • displayTransformability
Textual The document is set up for CSS display transformability.
  • enhancedAudio
Auditory For prerecorded audio content that contains primarily speech in the foreground.
  • /noBackground
  • /reducedBackground
  • /switchableBackground

AccessFeature for structure

There is only one property value for structuralNavigation, which is listed below.


Expected Values Description
  • structuralNavigation
table of contents or similar resource to allow higher-level document navigation, which can be extended as /tableofContents, /index, /headings, /tags, /bookmarks, /printedPageNumber if one wants to give more detail

AccessFeature for augmentation

Augmentation is the most interesting of the accessFeatures. It explains how an intelligent actor (generally a person, but could be computer-based) will take the intellectual content of one access mode and make it available in a different access mode. One can debate whether the source or the destination access mode is of more importance; I have chosen to organize this by the destination access mode that the source access mode was augmented to. Note that there is a common extension that is used to represent the refinement of the visual content types (see all of the /*OnVisual in access modes). so that one can express accessFeatures for specific parts of the visual content.

  • /text
  • /math
  • /chem
  • /diagram
  • /chart
  • /music


Expected Values Augmented Access Mode Source Access Mode (before augmentation) Description
  • alternativeText
Textual Visual alternative text is provided for visual content (e.g., the HTML alt attribute).
  • longDescription
Textual Visual descriptions are provided for image-based visual content and/or complex structures such as tables, mathematics, diagrams or charts.
  • ChemML
  • laTex
  • MathML
Textual Visual The use of one of these specific ASCII/XML encodings for mathematics or chemistry. These can have extensions specified, but are rarely needed.
  • transcript
Textual Auditory The addition of a separate transcript to convey the meaning of the audio.
  • captions
Visual Auditory The addition of synchronized text (closed captions) to convey the meaning of the audio. Note that while many captions may be implemented as textual in the transport, users think of them as being a visual appearance.
  • signLanguage
Visual Auditory The presentation of audio in sign language in the visual presentation. The most likely extension is /sgn-en-us or other ISO 639 sign language code.
  • audioDescription
Auditory Visual Audio descriptions are available (e.g., via the HTML5 track element). Common extensions are for the various "onImage" refinements noted above.
  • braille
Tactile Visual or Textual braille content or alternative is available (e.g., eBraille or print braille) This can have extensions for the different types of braille, /ASCII, /music, /math, /chem or /nemeth) (also consider /contracted and /gradeII or other nomenclature... pretty open)
  • tactileGraphic
Tactile Visual tactile graphics have been provided, as described in the BANA Guidelines and Standards for Tactile Graphics.
  • tactileObject
Tactile Visual tactile 3D objects have been defined and a 3D object or instructions to build one are available.

Example Markup

Example 1 (Book)

The following example shows how the accessibility metadata will be used to enhance Bookshare records. Note that our markuup has advanced since this early illustrative example. A description and the process and a corpus of searchable books can be found at the accessibility metadata website.

More examples are referenced in the Discussion and Related Work section.

  1. <div itemscope="" itemtype="http://schema.org/Book">
  2.    <meta itemprop="bookFormat" content="EBook/DAISY3"/>
  3.    <meta itemprop="accessMode" content="textual"/>
  4.    <meta itemprop="accessMode" content="visual"/>
  5.    <meta itemprop="isAdaptationOf" content="urn:isbn:9780030426599"/>
  6.    <meta itemprop="ATCompatible" content="true">
  7.    <meta itemprop="accessFeature" content="largePrint/CSSEnabled">
  8.    <meta itemprop="accessFeature" content="highContrast/CSSEnabled">
  9.    <meta itemprop="accessFeature" content="resizeText/CSSEnabled">
  10.    <meta itemprop="accessFeature" content="displayTransformability">
  11.    <meta itemprop="accessFeature" content="longDescription">
  12.    <meta itemprop="accessFeature" content="alternativeText">
  13.  
  14.    <dl>
  15.       <dt>Name:</dt>
  16.       <dd itemprop="name">Holt Physical Science</dd>
  17.       <dt>Brief Synopsis:</dt>
  18.       <dd itemprop="description">NIMAC-sourced textbook</dd>
  19.       <dt>Long Synopsis:</dt>
  20.       <dd>N/A</dd>
  21.       <dt>Book Quality:</dt>
  22.       <dd>Publisher Quality</dd>
  23.       <dt>Book Size:</dt>
  24.       <dd itemprop="numberOfPages">598 Pages</dd>
  25.       <dt>ISBN-13:</dt>
  26.       <dd itemprop="isbn">9780030426599</dd>
  27.       <dt>Publisher:</dt>
  28.       <dd itemprop="publisher" itemtype="http://schema.org/Organization" itemscope="">Holt, Rinehart and Winston</dd>
  29.       <dt>Date of Addition:</dt>
  30.       <dd>06/08/10</dd>
  31.       <dt>Copyright Date:</dt>
  32.       <dd itemprop="copyrightYear">2007</dd>
  33.       <dt>Copyrighted By:</dt>
  34.       <dd itemprop="copyrightHolder" itemtype="http://schema.org/Organization" itemscope="">Holt, Rinehart and Winston</dd>
  35.       <dt>Adult content:</dt>
  36.       <dd><meta itemprop="isFamilyFriendly" content="true"/>No</dd>
  37.       <dt>Language:</dt>
  38.       <dd><meta itemprop="inLanguage" content="en-US"/>English US</dd>
  39.       <dt>Essential Images:</dt>
  40.       <dd>861</dd>
  41.       <dt>Described Images:</dt>
  42.       <dd>910</dd>
  43.       <dt>Categories:</dt>
  44.       <dd><span itemprop="genre">Educational Materials</span></dd>
  45.       <dt>Grade Levels:</dt>
  46.       <dd>Sixth grade, Seventh grade, Eighth grade</dd>
  47.       <dt>Submitted By:</dt>
  48.       <dd>Bookshare Staff</dd>
  49.       <dt>NIMAC:</dt>
  50.       <dd>This book is currently only available to public K-12 schools and organizations in the United States for use with students with an IEP, because it was created from files supplied by the NIMAC under these restrictions. Learn more in the NIMAC Support Center.</dd>
  51.    </dl>
  52.  
  53.    <div class="bookReviews" itemprop="aggregateRating" itemscope itemtype="http://schema.org/AggregateRating">
  54.       <h2>Reviews of Holt Physical Science (<span itemprop="reviewCount">0</span> reviews)</h2>
  55.  
  56.       <div class="bookReviewScore">
  57.          <span><span itemprop="ratingValue>0</span> - No Rating Yet</span>
  58.       </div>
  59.    </div>
  60. </div>

(The source record can be found at https://www.bookshare.org/browse/book/190639.)

Example 2 (Video)

This example shows how the accessibility metadata can be used to augment a record for a video:

  1. <dl itemtype="http://schema.org/VideoObject" itemscope="">
  2.   <dt>Title:</dt>
  3.   <dd itemprop="name">Arctic Climate Perspectives</dd>
  4.   <dt>Description:</dt>
  5.   <dd itemprop="description">This video, adapted from material provided by the ECHO partners,
  6.     describes how global climate change is affecting Barrow, Alaska.</dd>
  7.   <dt>Adaptation Type:</dt>
  8.   <dd><span itemprop="accessFeature">captions</span></dd>
  9.   <dt>Access Mode:</dt>
  10.   <dd><span itemprop="accessMode">auditory</span>, <span itemprop="accessMode">visual</span></dd>
  11.   <dt>URL:</dt>
  12.   <dd><a itemprop="url" href="http://www.teachersdomain.org/asset/echo07_vid_climate">http://www.teachersdomain.org/asset/echo07_vid_climate</a>/</dd>
  13.   <dt>Has Adaptation:</dt>
  14.   <dd><a itemprop="hasAdaptation" href="http://www.teachersdomain.org/asset/echo07_vid_climate_dvs/">http://www.teachersdomain.org/asset/echo07_vid_climate_dvs/</a></dd>
  15.   <dt>Subjects:</dt>
  16.   <dd><span itemprop="about">National K-12 Subject::Science::Earth and Space Science::Water Cycle, Weather,
  17.     and Climate::Structure and Composition of the Atmosphere, National K-12 Subject::Science::Earth and
  18.     Space Science::Water Cycle, Weather, and Climate::Climate</span></dd>
  19.   <dt>Education Level:</dt>
  20.   <dd>Grade 6, Grade 7, Grade 8, Grade 9</dd>
  21.   <dt>Audience:</dt>
  22.   <dd><span itemprop="intendedEndUserRole">Learner</span></dd>
  23.   <dt>Resource Type:</dt>
  24.   <dd><span itemprop="genre">Audio/Visual</span>, <span itemprop="genre">Movie/Animation</span></dd>
  25.   <dt>Language:</dt>
  26.   <dd><span itemprop="inLanguage">en-US</span></dd>
  27.   <dt>Publication Date:</dt>
  28.   <dd itemprop="datePublished">2007-02-12</dd>
  29.   <dt>Rights:</dt>
  30.   <dd>Download and Share, <a itemprop="useRightsUrl" href="http://www.teachersdomain.org/oerlicense/2/">http://www.teachersdomain.org/oerlicense/2/</a></dd>
  31. </dl>

Issues Tracker and Open Issues

Issue Tracker, both open and closed

This list will be updated afte rthe first meeting

  • stuff (referring to open items, by name and number)

Discussion and Related Work