From W3C Wiki

This is an archived WebSchemas proposal Accessibility schema 1.1 for schema.org. See Proposals listing for more. Note: active schema.org development is now based at github


Making Accessible Content Discoverable

As V1.0 completed, there were open discussion items left around accessMode and isAdaptationOf and hasAdaptation. These issues, post 1.0, will be addressed in two different ways. The accessMode and use cases will be handled within this group. However, we are going to wait for the soon to be published BibEx workExample and exampleOfWork properties instead of using hasAdaption and isAdaptationOf.

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.


The accepted vocabulary so far is at WebSchemas/Accessibility. This page is to track ongoing work, alongside the Issue tracker (see below)

The "extended" proposal (post 1.0)

There were a few properties that are still under consideration, but have been deferred for a later release (V1.1). accessMode needs more work to allow both the source and the augmented access mode. The is/has adaptation links work will be done in concert with the Bibex group, with details and timing left to be determined. See also the Issues page (which will be edited down to the resolved issues for 1.0 and the open issues for future).

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. Note that there is also a discussion of an augmentedAccessMode for future effort.
hasAdaptation URL Identifier of a resource that is an adaptation, for accessibility purposes, for this resource. (to be handled with Bibex)
isAdaptationOf URL Identifier of a resource for which this is an adaptation for accessibility purposes. (to be handled with Bibex)

AccessFeature in more depth

The property accessFeature has multiple property values and groups of values.

Only the augmentation feature list follows, as this is different (additional columns) from the 1.0 page.

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.

Issues Tracker and Open Issues

Issue Tracker, both open and closed

Discussion and Related Work

There are many resources available on the main specification page. This page will list any unique resources and information beyond the 1.0 specification page.