Practical Properties Guide

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Tagging with accessibility metadata tags

If you've come this far, you're looking for answers to the question "how do I tag my catalog/ repository with accessibility metadata?" If you're already marking up your content with microdata/ schema.org, it's very easy... just add a few properties to your existing tagging.  Just describe how someone will access the content (auditory, visual, textual) and then describe any attributes of the content that make this content available for contexts besides the original intent (captions, transcripts, tactile graphics, braille). This will include special markup features that give more flexibility in presentation and transformation, such as the fact that there is marked-up mathematics or chemistry. Even then, we have a number of properties and values than can be specified, and it is not always clear which apply with which kind of electronic objects.  Physical items, such as books or other physical media, are also less clear. This document lays all of that information out by media type, physical object and mapping some of those to ONIX codes.

If you've not marked up your content with schema.org. the process can be more daunting. Schema.org lays out a very large number of potential properties, and you need to have a rudimentary start at microdata tagging to add the accessibility microdata tags. I especially like the answer that schema.org put in their FAQ to the question "Do I have to mark up every property?" The answer was "It is fine to mark up only some properties of an item - markup is not an all-or-nothing choice. However, marking up as much content as possible helps search engines use your information to present your page to users in the most useful way. As a general rule, you should mark up only the content that is visible to people who visit the web page and not content in hidden div's or other hidden page elements." This is great guidance, even though accessibility properties will often not be visible on the page and you have to do <meta> tags. Schema.org also has a very useful "getting started" page that describes how to use the information. It gives an overall view, while this document [and its children] and our somewhat more technical best practices guide V.6 and other information on the resources page give more specific accessibility tagging guidance.

Note that this page still refers to the property names and values for the .6 version of the specification. We'll update this page only if there is demand.

Properties Preface

We have two main properties, accessMode and accessibilityFeature that have a wide range of values. Only a subset of these values are relevant for any specific media type. Since one of the most common questions we face is "how do I tag this with schema.org tags... what's the object and the properties I should use?", this page expresses that in an easily consumed fashion. I am formatting this in a wiki for now, to get the information out and available as we refine this. Once it is stable, we can format it into a better presentation method. (Matt and I have proven that Wordpress, Google Docs and wikis are insufficient to present information in easy consumable ways, missing little things like spanned columns.)

Terms, which are defined further in the Access for All specifications and the best practices guide, used on this page include the following. Note that there is a great web accessibility page that describes these terms in much more detail, as well as in a small summary on our pageYou can also view a spreadsheet of all the possible terms, in this glossary.

Table of Contents

Electronic Media

Audio Media

Audio media is either pure audio, or audio that is wrapped in a video file, but the purpose of the video is solely to be a container for the adaptation, whether caption or sign language. If the adaptation is in another file there should be has/is Adaptation pointing back and forth. 

Issue Description Microdata tag
Schema.org object choose one from http://schema.org   
audio Pure audio schema.org: AudioObject
video Video used just as a carrier for accessibility (i.e., sign language)  
schema.org: VideoObject
  If search results could improve with most specific types, then use a more specific type such as MusicRecording
accessMode should always use auditory  
auditory Pure audio, audio with captions, video as media without primary visual content.
<meta itemprop="accessMode" content="auditory"/>
visual While one may think that visual should be used if it's the method to get sign language or alternative text out, it's there for the adaptation only. It should not be used for these special cases of audio.

accessibilityFeature use as many as relevant  
captions has captions timed to text (may require the object type to be video unless other display technology used, in which case the schema.org object type would be webApplication) <meta itemprop="accessibilityFeature" content="captions"/>
transcript text alternative in separate doc or pane that is not timed to the audio <meta itemprop="accessibilityFeature" content="transcript"/>
signLanguage requires object type to be video <meta itemprop="accessibilityFeature" content="signLanguage"/>
accessibilityHazard optional as relevant  
sound loud, repetitive sounds that can cause seizures are present <meta itemprop="accessibilityHazard" content="sound"/>

Audio Examples

An audio file, embedded in a web page with a transcript or link to the text description, would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/audioObject”>
<meta itemprop=”accessMode” content=”auditory”/>
<meta itemprop=”accessibilityFeature” content=”transcript”/>
</div>
A video file, with captions (either open or closed) and signLanguage, would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/videoObject”>
<meta itemprop=”accessMode” content=”auditory”/>
<meta itemprop=”accessibilityFeature” content=”captions”/>
<meta itemprop=”accessibilityFeature” content=”signLanguage”/>
</div>

Video

Issue
Description
Microdata tag
Schema.org object choose one from http://schema.org   
video
  schema.org: VideoObject
  If search results could improve with most specific types, then use a more specific type such as Movie, TVEpisode, TVSeries
accessMode
always use visual, use others as applicable
 
visual
  <meta itemprop="accessMode" content="visual"/>
auditory
the video has audio track
<meta itemprop="accessMode" content="auditory"/>
accessibilityFeature
use as many as relevant
 
captions
captions are available for audio and visual content
<meta itemprop="accessibilityFeature" content="captions"/>
audioDescription
audio begins before visuals or pauses visuals in the middle <meta itemprop="accessibilityFeature" content="audioDescription"/>
transcript
a transcript of the video is provided in a separate pane
<meta itemprop="accessibilityFeature" content="transcript"/>
accessibilityHazards optional as relevant
 
flashing
rates of flashing faster than 3Hz (3 times per second) which can cause seizures are present
<meta itemprop="accessibilityHazard" content="flashing"/>
sound
loud, repetitive sounds that can cause seizures are present
<meta itemprop="accessibilityHazard" content="sound"/>
motionSimulation
nausea can be caused by motion simulations
<meta itemprop="accessibilityHazard" content="motionSimulation"/>

Video Examples

A movie with captions and extended audio description would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Movie”>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessMode” content=”auditory”/>
<meta itemprop=”accessibilityFeature” content=”audioDescription”/>
<meta itemprop=”accessibilityFeature” content=”captions”/>
</div>
A movie with captions and fast flashing lights would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Movie”>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessMode” content=”auditory”/>
<meta itemprop=”accessibilityFeature” content=”captions”/>
<meta itemprop=”accessibilityHazard” content=”flashing”/>
</div>

Images - Static Visual Media

Issue Description Microdata Tag
Schema.org object choose one from http://schema.org  
image for a generic image schema.org/ImageObject
tactile if the image is one for tactile graphic production, use tactile rather than visual  
  If search results could improve with most specific types, then use more specific type such as Photograph, Map, Painting
accessMode
always use visual, apply others as relevant
 
visual
  <meta itemprop="accessMode" content="visual"/>
colorDependent
requires the ability to distinguish color
<meta itemprop="accessMode" content="colorDependent"/>
textOnImage
There is text in the image, and may not be legible at larger scales due to pixelation, or by text-to-speech software
<meta itemprop="accessMode" content="textOnImage"/>
accessibilityFeature use as many as relevant
 
alternativeText
alternative text is provided for visual content
<meta itemprop="accessibilityFeature" content="alternativeText"/>
audioDescription audio description of the image is available
<meta itemprop="accessibilityFeature" content="audioDescription"/>
largePrint resource is formatted for large print reading <meta itemprop="accessibilityFeature" content="largePrint"/>
tactileGraphic
image can be conveyed through touch, though it is not the primary method (this should conform to the BANA guidelines and standards for tactile graphics)
<meta itemprop="accessibilityFeature" content="tactileGraphic"/>
tactileObject
the image is a picture of a 3D object, which can be expressed by a 3D model or build instructions <meta itemprop="accessibilityFeature" content="tactileObject"/>
highContrast
high contrast options are provided
<meta itemprop="accessibilityFeature" content="highContrast"/>
longDescription
text descriptions are provided for image-based content
<meta itemprop="accessibilityFeature" content="longDescription"/>

Visual Media Examples

A jpg image, with an audio description provided on the same pane would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/imageobject”>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessibilityFeature” content=”audioDescription”/>
</div>
A color coded map has a long text description on the same pane would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/map”>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessMode” content=”colorDependent”/>
<meta itemprop=”accessibilityFeature” content=”longDescription”/>
</div>
A map that is distributed as a printable PNG, JPG or PDF, that, when properly printed is raised so that information is conveyed through touch. Callouts are in braille would be encoded as follows. If the map were also done in such a way that it conveyed all of the information in visual form, both accessModes could be used.
<div itemscope=”” itemtype=”http://schema.org/map”>
<meta itemprop=”accessMode” content=”tactile”/>
<meta itemprop=”accessibilityFeature” content=”tactileGraphic”/>
<meta itemprop=”accessibilityFeature” content=”braille”/>
</div>

HTML Documents

Issue Description Microdata tag
Schema.org object
choose one from http://schema.org
 
  If search results could improve with most specific types, then use more specific type such as WebPage, Blog, Recipe
accessMode
   
textual
  <meta itemprop="accessMode" content="textual"/>
visual
The document includes images that are integral to the comprehension of the subject matter
<meta itemprop="accessMode" content="visual"/>
accessibilityFeature
use as many as relevant
 
alternativeText
alternative text is provided for visual content
<meta itemprop="accessibilityFeature" content="alternativeText"/>
longDescription descriptions are provided for image-based content and/or complex structures such as tables
<meta itemprop="accessibilityFeature" content="longDescription"/>
ChemML chemistry equations and formulas are provided in ChemML format
<meta itemprop="accessibilityFeature" content="ChemML"/>
MathML math content is provided in MathML format
<meta itemprop="accessibilityFeature" content="MathML"/>
structuralNavigation
resource provides a table of contents or similar resource to allow higher-level document navigation <meta itemprop="accessibilityFeature" content="structuralNavigation"/>
displayTransformability
aspects of the rendering can be controlled by the user
<meta itemprop="accessibilityFeature" content="displayTransformabilty"/>
describedMath
descriptions are provided for math content
<meta itemprop="accessibilityFeature" content="describedMath"/>

HTML Document Example

A DIY Blog post with text and images showing each step of the project, with alternative text provided would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Blog”>
<meta itemprop=”accessMode” content=”textual”/>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessibilityFeature” content=”alternativeText”/>
<meta itemprop=”accessibilityFeature” content=”displayTransformability”/>
</div>

Programs: HTML Interactive, Mobile applications or standalone software, electronic games (Wii, PlayStation, etc.)

Issue Description Microdata Tag
Schema.org object
choose one from http://schema.org
 
SoftwareApplication
  schema.org/SoftwareApplication
  If search results could improve with most specific types, then use more specific type such as WebApplication, or MobileApplication
accessMode
always use visual, use others as relevant
 
visual
Images or animation is included as part of the interactive <meta itemprop="accessMode" content="visual"/>
textual
Text is included as part of the interactive
<meta itemprop="accessMode" content="textual"/>
auditory
There is an audio component that is integral to the comprehension of the subject matter
<meta itemprop="accessMode" content="auditory"/>
colorDependent
requires the ability to distinguish color <meta itemprop="accessMode" content="colorDependent"/>
textOnImage
There is text in the image, and may not be legible at larger scales due to pixelation, or by text-to-speech software <meta itemprop="accessMode" content="textOnImage"/>
accessibilityFeature
use as many as relevant
 
alternativeText
alternative text is provided for visual content <meta itemprop="accessibilityFeature" content="alternativeText"/>
longDescription
text descriptions are provided for image-based content
<meta itemprop="accessibilityFeature" content="longDescription"/>
controlFlexibility
use as relevant (can be multiple)

fullKeyboardControl
can be used solely with the keyboard control and still have complete control <meta itemprop="controlFlexibility" content="fullKeyboardControl"/>
fullMouseControl can be used solely with the mouse
<meta itemprop="controlFlexibility" content="fullMouseControl"/>
fullAudioControl can be used solely with the an audio interface
<meta itemprop="controlFlexibility" content="fullAudioControl"/>
fullTouchControl can be used solely with touch
<meta itemprop="controlFlexibility" content="fullTouchControl"/>
fullVideoControl can be used solely with video interface
<meta itemprop="controlFlexibility" content="fullVideoControl"/>

HTML Interactive Example

A teaching resource using images, text, and questions, allowing full application control with the mouse, would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/WebApplication”>
<meta itemprop=”accessMode” content=”textual”/>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”controlFlexibility” content=”fullMouseControl”/>
</div>

Text Documents

Issue Description Microdata Tag
Schema.org object
choose from http://schema.org  
CreativeWork
for a generic or undefinable work
schema.org/CreativeWork
  If search results could improve with most specific types, then use more specific type such as Article, Book
accessMode
always use textual, use others as relevant
 
textual
  <meta itemprop="accessMode" content="textual"/>
visual
document includes images
<meta itemprop="accessMode" content="visual"/>
textOnImage
document includes scanned images of text
<meta itemprop="accessMode" content="textOnImage"/>
colorDependent
requires the ability to distinguish color <meta itemprop="accessMode" content="colorDependent"/>
accessibilityFeature
use as relevant
 
alternativeText     alternative text is provided for visual content 
 
<meta itemprop="accessibilityFeature" content="alternativeText"/>
longDescription
text descriptions are provided for image-based content <meta itemprop="accessibilityFeature" content="longDescription"/>

Text Document example

A plain text file, hard line breaks (not transformable) would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Article”>
<meta itemprop=”accessMode” content=”textual”/>
</div>

PDFs

Issue Description Microdata Tag
Schema.org object
choose from http://schema.org
CreativeWork
for generic or undefinable Creative work
schema.org/CreativeWork
  If search results could improve with most specific types, then use more specific type such as Article, Book
accessMode

 
textual
document contains text (images of text as scanned pages do not count unless OCRed) <meta itemprop="accessMode" content="textual"/>
visual
document includes images
<meta itemprop="accessMode" content="visual"/>
textOnImage
document includes scanned images of text
<meta itemprop="accessMode" content="textOnImage"/>
colorDependent
requires the ability to distinguish color <meta itemprop="accessMode" content="colorDependent"/>
accessibilityFeature
use as relevant
 
alternativeText
short text descriptions are provided for image-based content <meta itemprop="accessibilityFeature" content="alternativeText"/>
displayTransformatibility
used when the document is a tagged PDF so that the content can be reflowed <meta itemprop="accessibilityFeature" content="displayTransformability"/>

PDF example

A PDF with images and text description would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Article”>
<meta itemprop=”accessMode” content=”textual”/>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessibilityFeature” content=”longDescription”/>
</div>

Items on the Cusp of Physical and Electronic - Books and Ebooks

Physical Books and Magazines (print, braille) and ebooks in general

Issue Description
Microdata Tag
schema.org object
choose from http://schema.org  
Book
  schema.org/Book
  If search results could improve with most specific types, then use more specific type such as Magazine, Article
accessMode always use textual, use others as relevant
 
textual information is conveyed through text <meta itemprop="accessMode" content="textual"/>
visual the resource includes images that are integral to the comprehension of the content, such as pictures or charts
<meta itemprop="accessMode" content="visual"/>
colorDependent
information on the page requires the ability to distinguish color <meta itemprop="accessMode" content="colorDependent"/>
textOnImage
There is text in graphics in the book, which may not be readable by text-to-speech software <meta itemprop="accessMode" content="textOnImage"/>
accessibilityFeature use as many as relevant
 
alternativeText
alternative text is provided for visual content
<meta itemprop="accessibilityFeature" content="alternativeText"/>
braille braille content or alternative is available (e.g., eBraille or print braille) <meta itemprop="accessibilityFeature" content="braille"/>
highContrast high contrast options are provided <meta itemprop="accessibilityFeature" content="highContrast"/>
largePrint
resource is formatted for large print reading <meta itemprop="accessibilityFeature" content="largePrint"/>
longDescription
text descriptions are provided for image-based content
<meta itemprop="accessibilityFeature" content="longDescription"/>
MathML, ChemML, Latex    
nemethBraille
math content is available in Nemeth braille format <meta itemprop="accessibilityFeature" content="nemethBraille"/>
musicBraille
music content is available in music braille format <meta itemprop="accessibilityFeature" content="musicBraille"/>
musicLargePrint music is formatted for large print reading <meta itemprop="accessibilityFeature" content="musicLargePrint"/>

Physical Book/Magazine examples

A book in large print with detailed color images, charts and graphs would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Book”>
<meta itemprop=”accessMode” content=”textual”/>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessMode” content=”colorDependent”/>
<meta itemprop=”accessibilityFeature” content=”largePrint”/>
</div>
An algebra book printed in braille would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Book”>
<meta itemprop=”accessMode” content=”tactile”/>
<meta itemprop=”accessibilityFeature” content=”braille”/>
<meta itemprop=”accessibilityFeature” content=”nemethBraille”/>
</div>
An algebra book available as an electronic book in BRF braille would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Book”>
<meta itemprop=”accessMode” content=”tactile”/>
<meta itemprop=”accessibilityFeature” content=”braille”/>
<meta itemprop=”accessibilityFeature” content=”nemethBraille”/>
<meta itemprop=”bookFormat” content=”EBook”/>
</div>

Daisy eBooks

Here you can see the ONIX list and value for eBooks, as well as the correct A11Y metadata type.  Please follow that reference up the page.

For other eBook formats, see Book, above.

ONIX List ONIX value Onix label Description
A11Y metadata type
78 A201 DAISY 2: full audio with title only (no navigation) Deprecated, as does not meet DAISY 2 standard. Use conventional audiobook codes instead. see Audio Media
78 A202 DAISY 2: full audio with navigation (no text)   see Audio Media
accessibilityFeature:structualNavigation
78 A203 DAISY 2: full audio with navigation and partial text   see Audio Media
accessMode: auditory
accessMode: textual
78 A204 DAISY 2: full audio with navigation and full text   see Audio Media
accessMode:textual
accessibilityFeature:structuralNavigation
78 A205 DAISY 2: full text with navigation and partial audio Reading systems may provide full audio via text-to-speech. See Book
accessibilityFeature:structuralNavigation
78 A206 DAISY 2: full text with navigation and no audio Reading systems may provide full audio via text-to-speech. see Book
accessibilityFeature:structuralNavigation
78 A207 DAISY 3: full audio with title only (no navigation) Deprecated, as does not meet DAISY 3 standard. Use conventional audiobook codes instead. see Audio Media
78 A208 DAISY 3: full audio with navigation (no text)   see Audio Media
accessibilityFeature:structuralNavigation
78 A209 DAISY 3: full audio with navigation and partial text   see Audio Media
accessibilityFeature:structuralNavigation
78 A210 DAISY 3: full audio with navigation and full text   see Book
accessMode:textual
accessMode:auditory
accessibilityFeature:structuralNavigation
78 A211 DAISY 3: full text with navigation and some audio Reading systems may provide full audio via text-to-speech. see Book
accessibilityFeature:structuralNavigation
78 A212 DAISY 3: full text with navigation (no audio) Reading systems may provide full audio via text-to-speech. see Book
accessibilityFeature:structuralNavigation

Physical Media or Items in Stores (coded with ONIX codes)

Another way stores know and display content is through ONIX codes that are used to drive the commerce systems.  The full list is available on the ONIX site, as we're just creating an excerpt here for the most commonly used. We specifically used ONIX 3.0 Codelist issue 21.

Before we get into ONIX types, there are some physical items that need to be considered.

Tactile items

Issue
Description
Microdata tag
schema.org object
choose from http://schema.org

CreativeWork
for generic or undefinable items
schema.org/CreativeWork
  If search results could improve with most specific types, then use more specific type such as Book, Sculpture
More specific types should be added to schema.org and have been suggested outside this effort.  See this project for examples:
http://www.essepuntato.it/lode/http:/purl.org/library/#d4e306
accessMode
always use tactile, use others as relevant
 
tactile
information is conveyed through touch <meta itemprop="accessMode" content="tactile"/>
textual
information is conveyed through text
<meta itemprop="accessMode" content="textual"/>
visual
information is conveyed through sight
<meta itemprop="accessMode" content="visual"/>
accessibilityFeature
use as many as relevant
 
braille
braille content or alternative is available (e.g., eBraille or print braille) <meta itemprop="accessibilityFeature" content="braille"/>
tactileGraphic
tactile graphics are provided <meta itemprop="accessibilityFeature" content="tactileGraphic"/>

Tactile examples

A children's book using text, pictures and tactile objects (such as Pat the Bunny) would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/Book”>
<meta itemprop=”accessMode” content=”textual”/>
<meta itemprop=”accessMode” content=”visual”/>
<meta itemprop=”accessMode” content=”tactile”/>
</div>
A physical learning resource: a set of objects to portray the solar system, with the text in braille, would be encoded as follows
<div itemscope=”” itemtype=”http://schema.org/ImageObject”>
<meta itemprop=”accessMode” content=”tactile”/>
<meta itemprop=”accessMode” content=”textual”/>
<meta itemprop=”accessibilityFeature” content=”tactileObject”/>
<meta itemprop=”accessibilityFeature” content=”braille”/>
</div>

(note that we considered doing this as "Sculpture" instead of ImageObject, but this is not indexed well by search engines today. Since you can either describe the object, or the image that shows the object, sculpture or imageobject could be the right thing).

schema.org/ImageObject

Other ONIX physical media

ONIX List ONIX value Onix label A11Y metadata type
7 AB Analog audio cassette Audio
7 DM USB Flash Drive Depends on the content being distributed
7 VJ VHS Video Video
7
DB
CD-ROM
Depends on the content being distributed
7
AD
Digital Audio Cassette
Audio
7
VI
DVD video
Video
7
AI
DVD audio
Audio
7
DI
DVD-ROM
Depends on the content being distributed
7
AC
CD-Audio
Audio
7
PZ
Other printed material (Non-book)  Use more specific if possible
Depends on the content - see Text document
7
PH
Kit
Tactile items or a missing resource type in schema.org (see note in tactile)
7
ZE
Game (except computer game)
Tactile items (see note in tactile about missing types)
7
DE
Game cartridge (computer game)
SoftwareApplication
7
AA
Audio recording (unspecified)
Audio
7
ZZ
Other general merchandise
Tactile Items, or missing item, or product
10 041 Android app
MobileApplication
21
BRL
Braille
Book
21 LTE Large Print
Depends on the content being distributed - see Book, PDF, Text document
34
02
HTML file
HTML documents
34
08
PDF
PDF
34
06
Text file (default)
Text document
34
09
Microsoft Rich Text Format (RTF)
Depends on the content being distributed - see Book, Text document
39
02
GIF
Video
39 03
JPG
Images
39 05
TIF
Images
39 07
Mp3
Audio
150
ED
Digital download
Depends on the content being distributed
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