Certifier Credential: 
This work has moved into the W3C’s EPUB 3 Community Group and can be found at this Github repository, here is a rendered view of the latest draft of this work UX Guide for displaying accessibility metadata Principles and UX Guide for displaying accessibility metadata Techniques.
Any future work should be done via the W3C’s EPUB3 Community Groups Github repositories.
OBSOLETE as has been moved to the W3C, (Until which time as the W3C’s documents are published this is the most up-to-date and inclusive reference document and is still valid.)
Editors Draft - Version 0.9 (05/24/2019) Editors Draft - Version 0.9.1 (10/08/2019) - Fixed Example for Screen Reader Friendly
This document was published by the DIAGRAM Center Standards Working Group and DAISY’s Transition to EPUB Working group as an Editor’s Draft.
Comments regarding this document are welcome. Please file an issue using our GitHub repository issue tracker.
This document will help those who wish to provide accessibility metadata directly to users understand how to represent machine readable accessibility metadata in a user friendly User Interface / User Experience (UI/UX).
Metadata found either inside an EPUB or in its corresponding ONIX file may have important accessibility information that will help end users find and determine if this EPUB can meet their specific accessibility needs.
Most metadata is meant to be machine readable so that it can be used to aid in user search queries such as Find all EPUB books that contain large print, or braille, or that has met a certain level of accessibility conformance.
The exception to this is the accessibility summary which, if present, describes in human-readable text all the accessibility features and any shortcomings present in this book that can be directly presented to the end user.
NOTE: All images provided here may be protected under copyright and are only used as a reference.
Here is an example of what a user-friendly accessibility metadata web page could look like:
Screen Reader Friendly: Yes
Accessibility Summary: This publication includes markup to enable accessibility and compatibility with assistive technology. Images, audio, and video in the publication are well-described in conformance with WCAG 2.0 AA.
EPUB Accessibility Conformance: WCAG-AA
Certified By: ACME Certification
Certifier Credential:
All Accessibility Metadata:
The guidelines for presentation of accessibility metadata in this document are intended to improve the user experience when readers browse the catalog entry for a book. However, accessibility metadata also has a vital role to play in helping readers discover books that are accessible for them. Book providers, vendors, and libraries are encouraged to create searching and filtering tools that interpret accessibility metadata to aid in discovery; a full discussion of this topic is out of scope for this document, but these brief notes may be helpful until further research and development leads to more specific guidance.
While every user has different accessibility needs, meeting the Web Content Accessibility Guidelines (WCAG) 2.0 requirements, even at level A, is a baseline that ensures a book will be widely accessible. Book providers may therefore wish to create specific search capabilities to permit users to find books that have declared conformance to WCAG at any level. A search filter called Accessible
that retrieves all books with metadata of <link rel="dcterms:conformsTo" href="http://www.idpf.org/epub/a11y/accessibility-20170105.html#wcag-a" /> or the equivalent for wcag-aa and ultimately for wcag-aaa would fill this need.
Audiobooks created for mainstream use provide important access for many users with disabilities even though they are not accessible to others. Book providers may already have search tools aimed at finding audiobooks, since they are popular and fairly common, but if not, this would be a good addition to the suite of tools for finding accessible books. Note that audiobooks may not pass WCAG requirements because they are targeted at a specific audience rather than broadly accessible and so would not be found using the Accessible
search suggested above.
Any of the metadata fields discussed in detail below could also be used as a filter; a Screen-reader accessible
search would be valued by screen reader users, and a way to ensure no books with hazards are downloaded would be valued by those with light-sensitive epilepsy or other hazard-related conditions. But if a single additional search filter fits best in a site’s UI, a tool for finding accessible materials that declare conformance to WCAG 2.0 is the most likely choice.
When you have accessibility metadata about an EPUB it is important to share this information with the user in a user friendly way. At a very high level when displaying information about an EPUB you may just want to acknowledge that there is Accessibility Features
or Accessibility Information
available and if the user would like to get at this information they can click a link or an image which will then provide the information that is discussed below.
For Example:
Title: Huckleberry Finn
Author: Mark Twain
Copyright: 1999
ISBN: 9780486110035
Publisher: Dover Publications
Book Features: Accessibility Information (textual link to accessibility information below)
Or
Book Features:
(clickable image to accessibility information below)
Suggested Alt-text for image
Accessibility Information
Audiobook (if present)
Certifier’s Report (if present)
This metadata as outlined in the 1.0 Accessibility Specification Conformance and Discoverability can be found inside the EPUB’s opf file usually found in OEBPS/package.opf
Note: At the end of this document are the ONIX equivalent metadata for each of these, if defined. While the examples shown here are for EPUB 3.x, there are equivalents for EPUB 2.x which can be found in the Accessibility 1.0 specification.
Value: Yes / No / Unknown
This data is derived from the EPUB package metadata inside the OPF file:
If this metadata exists (ie. textual
within accessModeSufficient by itself) then report Screen Reader Friendly: Yes
Important: This is not the same as visual, textual
or textual, visual
because the combination means that the book requires both visual and textual abilities to access the data, not textual alone. Only having accessModeSufficient be textual
as a separate entry ensures the document is screen reader friendly.
Note: As long as there is an entry that reads
<meta property="schema:accessModeSufficient">textual</meta>the book can claimScreen Reader Friendly: Yes.
There may also be other accessModeSufficient entries with combinations of access modes such as textual, visual
which indicate other ways to read the book.
When accessModeSufficient exists but does not have textual
by itself, report Screen Reader Friendly: No
.
When there is no accessModeSufficient metadata present, report Screen Reader Friendly: unknown or not provided
.
Screen Reader Friendly: Yes
(because textual was present by itself in accessModeSufficient)
accessModeSufficient fields present)<meta property="schema:accessModeSufficient">visual</meta>
<meta property="schema:accessModeSufficient">textual</meta>
<meta property="schema:accessModeSufficient">textual, visual</meta>Screen Reader Friendly: Yes
(because textual was present by itself in accessModeSufficient)
<meta property="schema:accessModeSufficient">visual</meta>
<meta property="schema:accessModeSufficient">textual, visual</meta>Screen Reader Friendly: No
(because textual was not present by itself in accessModeSufficient)
""
Screen Reader Friendly: Unknown
(because accessModeSufficient is not found at all in the metadata)
Values: Yes / (if No - Omit this section)
This data is derived from the EPUB package metadata inside the OPF file:
If this metadata exists (ie. auditory
within accessModeSufficient by itself) then report Audiobook: Yes
.
Important: This is not the same as textual, auditory
or auditory, textual
as this indicates that the book requires both textual and auditory abilities to access the data, not auditory alone. Only having accessModeSufficient be auditory
as a separate entry ensures the document is an audiobook.
Note: As long as you find
<meta property="schema:accessModeSufficient">auditory</meta>the book can claimAudiobook: Yes.
There may also be other accessModeSufficient entries with combinations of access modes such as textual, visual
which indicate other ways to read the book.
Note: If you can not report that this is an audiobook then do not present any information to the user for this category, since 99% of EPUB books are not audiobooks. Simply omit this section.
<meta property="schema:accessModeSufficient">auditory</meta>
<meta property="schema:accessModeSufficient">visual</meta>Audiobook: Yes
(because auditory
was found alone in accessModeSufficient)
<meta property="schema:accessModeSufficient">visual</meta>
<meta property="schema:accessModeSufficient">auditory, visual</meta>Omit this section
(Nothing presented to the user because auditory
was not found alone in accessModeSufficient)
""
Omit this section
(Nothing presented to the user because accessModeSufficient is not present at all in the metadata)
Value: Textual Data from metadata
This data is pulled directly from the EPUB package metadata inside the OPF file:
Note: We will be creating additional guidance for publishers on how to best write these summaries.
Note: If the metadata does not exist this should say
No Summary Available
Note: This data could be in a language other than English but would be tagged as such.
<meta property="schema:accessibilitySummary">
This publication includes markup to enable accessibility and compatibility with assistive technology. Images, audio, and video in the publication are well-described in conformance with WCAG 2.0 AA. Structural navigation may be inconsistent.
</meta>Accessibility Summary:
This publication includes markup to enable accessibility and compatibility with assistive technology. Images, audio, and video in the publication are well-described in conformance with WCAG 2.0 A.
""
Accessibility Summary: None provided
Value: Textual Link based on Metadata (WCAG-A, WCAG-AA, WCAG-AAA) or raw URL found in EPUB OPF file’s metadata field
Note: Interpret this metadata to be as human friendly as possible. So if the URI is:
If the URL is anything other than the three listed above, then providing the raw URL which is also a link is the only option, since this may be a link to a different conformance standard (i.e. some audio conformance specification for an audio book).
Note: A case insensitive comparison should be done to replace the URI with human-readable text for WCAG-AA, etc.
Note: If you do not wish to have clickable links here, you may omit them as long as you make the links available in the section All Accessibility Metadata, described below.
Note: The above three URIs could change in the future since they point to an IDPF page; this work has been moved to the W3C. If a change occurs, other URIs will be recommended.
EPUB Accessibility Conformance: WCAG-AA
(Because this links to one of the three URIs outlined above)
EPUB Accessibility Conformance: Custom specification
(Because this URI is different than what was outlined above. The book may qualify for conformance as an optimized publication.)
""
EPUB Accessibility Conformance: None provided
Value: Textual Data from metadata
This data is pulled directly from the EPUB package metadata inside the OPF file:
Note: If the metadata does not exist this should say
None provided
Certified By: 3rd Party Company Name
Self Certified By: Publisher Name
""
Certified By: None provided
Value: Potentially linked textual data from metadata
This data is pulled directly from the EPUB package metadata inside the OPF file:
Note: This metadata could be a simple text string in which case you would just display it, or it could be a URI to the certifier’s credential web page.
If the metadata value is a URI, you could have some standard certification logo which would be clickable and link to the certifier’s credential webpage.
If you do not wish to have clickable links here, you may omit them as long as you make the links available in the section All Accessibility Metadata, described below.
If you are aware of a list of organizations who offer third-party certification, a short list of certifier’s logos could be cached and displayed when appropriate. For example:
Certifier Credential: XYZ Certified Accessible
<meta property="a11y:certifiedBy">ACME Inc.</meta>
<meta property="a11y:certifierCredential">https://3rd-party-certifier-credential.com</meta>Certifier Credential
(Clickable Image to the URI of the certifiers credential’s webpage from metadata)
alt-text
ACME Inc. credential webpage(Image here of a checkmark inside a shield is just for reference feel free to choose your own image)
Note: There may be an image that is associated with specific Certifier Credential image (ie. Mark/Stamp/Seal) which could be used here. If you would like to display this image, or any other, you would need to be coordinate this out of band with the certifier agency as it is not part of the metadata delivered with the book.
Or
Certifier’s Credential: ACME Inc. credential webpage
(Clickable link to the URI to the certifiers credentials from metadata)
""
Certifier Credential: None provided
Value: Potentially linked textual data from metadata
This data is pulled directly from the EPUB package metadata inside the OPF file:
Ideally you would have a clickable link to the certification accessibility report.
If you do not wish to have clickable links here, you may omit them as long as you make the links available in the section All Accessibility Metadata, described below.
<meta property="a11y:certifiedBy">ACME Inc.</meta>
<link rel="a11y:certifierReport" href="http://www.example.com/a11y/report/9780000000001"/>Certifier Report
(Clickable Image to the URI of the report from metadata)
alt-text
ACME Inc. Report webpage(Image here of checkmark with clipboard is just for reference feel free to choose your own image)
Or
Certifier Report: ACME Inc. Accessibility Report
(Clickable link to the URI of the report from metadata)
""
Omit this section
(Omit this section if the metadata is missing, as most of the time there will be no report available.)
Values: flashing, motion simulation, sound, no flashing, no motion simulation, no sound, none, or Unknown.
This data is found in the EPUB package metadata inside the OPF file:
Hazards are the only metadata which can be expressed as either positive or negative statements, so metadata authors can confirm either the presence of the hazard, such as flashing
, or the absence of the hazard, noFlashingHazard
and similarly for sound / noSoundHazard
and motion / noMotionSimulationHazard
. There is also the metadata value none
, which covers all three categories and corresponds to noFlashingHazard
, noSoundHazard
and noMotionSimulationHazard
.
Note: In the section
All Accessibility MetadataHazards will be displayed exactly how the publisher provided them so simplifying here with usingnonecan be an option instead of saying explicitlyno Sound, no Flashing, no Motion Simulation
Hazard: Flashing
(because flashing
was found in accessibilityHazard)
Hazard: Motion Simulation
(because motionSimulation
was found in accessibilityHazard)
Hazard: Sound
(because sound
was found in accessibilityHazard)
<meta property="schema:accessibilityHazard">sound</meta>
<meta property="schema:accessibilityHazard">motionSimulation</meta>
<meta property="schema:accessibilityHazard">flashing</meta>Hazard: Sound, Motion Simulation, and Flashing
(because sound
, motionSimulation
, flashing
and were all found in accessibilityHazard)
Omit this section
Or
Hazards: none provided
Nothing presented to the user because there are no hazards; since 99.9% of EPUBs won’t have any hazards, there is no need to report Hazards: No
for every EPUB.
noFlashingHazard, noSoundHazard, and noSimulation)<meta property="schema:accessibilityHazard">noFlashingHazard</meta>
<meta property="schema:accessibilityHazard">noSoundHazard</meta>
<meta property="schema:accessibilityHazard">noMotionSimulationHazard</meta>Omit this section
Or
Hazards: none
Or
Hazards: No Flashing, No Sound, No Motion Simulation
""
Hazards: None provided
We want to make the distinction here between No Hazards and missing hazard metadata therefore for the missing metadata case we need to inform the user we don’t know about any hazards which may or maynot be present.
Value: Link to complete list of all metadata fields
Here are all the possible accessibility metadata properties.
This section can either be a separate page that is linked to or better yet an HTML Summary/Details element that users can expand to get all the accessibility metadata field elements. Here you would expose: accessibilityFeature, accessibilityHazard, accessMode, accessModeSufficient, as well as all the accessibility metadata and conformance metadata listed above.
<meta property="schema:accessibilityFeature">alternativeText</meta>
<meta property="schema:accessibilityFeature">longDescription</meta>
<meta property="schema:accessibilityFeature">printPageNumbers</meta>
<meta property="schema:accessibilityHazards">noSoundHazard</meta>
<meta property="schema:accessibilityHazards">noMotionSimulationHazard</meta>
<meta property="schema:accessibilityHazards">noFlashingHazard</meta>
<meta property="schema:accessMode">visual</meta>
<meta property="schema:accessMode">textual</meta>
<meta property="schema:accessModeSufficient">visual</meta>
<meta property="schema:accessModeSufficient">textual</meta>
<meta property="schema:accessModeSufficient">visual,textual</meta>
<meta property="a11y:certifiedBy">ACME Certification</meta>
<meta property="a11y:certifierCredential">https://ACME-Certification.org/</meta>
<link rel="dcterms:conformsTo" href="http://www.idpf.org/epub/a11y/accessibility-20170105.html#wcag-a/" />
<meta property="schema:accessibilitySummary">
This publication includes mark-up to enable accessibility and compatibility with assistive technology. Images, audio, and video in the publication are well-described in conformance with WCAG 2.0 A.
</meta>Accessibility Features:
alternativeText
longDescriptions
printPageNumbers
Accessibility Hazards:
No Sound Hazard
No Motion Simulation Hazard
No Flashing Hazard
AccessMode:
visual
textual
Access Mode Sufficient:
visual
textual
visual, textual
Certified By:
ACME Certification
Certifier’s Credential:
https://ACME-Certification.org/
Conforms To:
http://www.idpf.org/epub/a11y/accessibility-20170105.html#wcag-a
Accessibility Summary:
This publication includes markup to enable accessibility and compatibility with assistive technology. Images, audio, and video in the publication are well-described in conformance with WCAG 2.0 A.
""
Accessibility Features:
None provided
Accessibility Hazards:
None provided
AccessMode:
None provided
Access Mode Sufficient:
None provided
Certified By:
None provided
Certifier’s Credential:
None provided
Conforms To:
None provided
Accessibility Summary:
None provided
Note:
ONIX does not have an exact 1:1 mapping with EPUB accessibility metadata so unfortunately not all of the accessibility metadata found in an EPUB exists in ONIX at the time of this publication. There are plans to add this metadata to future versions of ONIX but no time frame has been announced. This EPUB to ONIX crosswalk outlines the current overlap in metadata which will get updated as these two specifications evolve. It is important to note that there were a number of new accessibility metadata codes added to ONIX 3 to support the Accessibility 1.0 specification. Which means that ONIX 2 has a limited number of accessibility metadata codes and is something not covered in this document.
Here is an example of an ONIX feed (version 3.0), which will be used as a reference point for the following examples on EPUB accessibility metadata: the results of the XPath shown are based on this example.
<?xml version="1.0" encoding="UTF-8"?>
<ONIXMessage xmlns="http://ns.editeur.org/onix/3.0/reference" release="3.0">
<Header>...</Header>
<Product>
<RecordReference>123456789</RecordReference>
<NotificationType>01</NotificationType>
<ProductIdentifier>
<ProductIDType>03</ProductIDType>
<IDValue>9780000000000</IDValue>
</ProductIdentifier>
<ProductIdentifier>
<ProductIDType>15</ProductIDType>
<IDValue>9780000000000</IDValue>
</ProductIdentifier>
<DescriptiveDetail>
<ProductComposition>00</ProductComposition>
<ProductForm>ED</ProductForm>
<ProductFormDetail>E101</ProductFormDetail>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>00</ProductFormFeatureValue>
<ProductFormFeatureDescription>
This publication includes mark-up to enable accessibility and compatibility with assistive technology. Images, audio, and video in the publication are well-described in conformance with WCAG 2.0 A.
</ProductFormFeatureDescription>
</ProductFormFeature>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>03</ProductFormFeatureValue>
</ProductFormFeature>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>10</ProductFormFeatureValue>
</ProductFormFeature>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>11</ProductFormFeatureValue>
</ProductFormFeature>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>13</ProductFormFeatureValue>
</ProductFormFeature>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>14</ProductFormFeatureValue>
</ProductFormFeature>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>22</ProductFormFeatureValue>
</ProductFormFeature>
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>94</ProductFormFeatureValue>
<ProductFormFeatureDescription>http://www.example.com/a11y/report/9780000000001</ProductFormFeatureDescription>
</ProductFormFeature>
<PrimaryContentType>10</PrimaryContentType>
<EpubTechnicalProtection>03</EpubTechnicalProtection>
<EpubUsageConstraint>
<EpubUsageType>04</EpubUsageType>
<EpubUsageStatus>02</EpubUsageStatus>
</EpubUsageConstraint>
<TitleDetail>...</TitleDetail>
<Contributor>...</Contributor>
<Extent>...</Extent>
<Subject>...</Subject>
</DescriptiveDetail>
<CollateralDetail>...</CollateralDetail>
<PublishingDetail>...</PublishingDetail>
<RelatedMaterial>...</RelatedMaterial>
<ProductSupply>...</ProductSupply>
</Product>
</ONIXMessage><?xml version="1.0" encoding="UTF-8"?>
<ONIXMessage xmlns="http://ns.editeur.org/onix/3.0/reference" release="3.0">
<Header>...</Header>
<Product>
<RecordReference>123456789</RecordReference>
<NotificationType>01</NotificationType>
<ProductIdentifier>
<ProductIDType>03</ProductIDType>
<IDValue>0000000000000</IDValue>
</ProductIdentifier>
<DescriptiveDetail>
<ProductComposition>00</ProductComposition>
<ProductForm>AO</ProductForm>
<PrimaryContentType>01</PrimaryContentType>
...
<TitleDetail>...</TitleDetail>
<Contributor>...</Contributor>
<Extent>...</Extent>
<Subject>...</Subject>
</DescriptiveDetail>
<CollateralDetail>...</CollateralDetail>
<PublishingDetail>...</PublishingDetail>
<RelatedMaterial>...</RelatedMaterial>
<ProductSupply>...</ProductSupply>
</Product>
</ONIXMessage>The ONIX standard, unlike the Schema.org standard, provides a method to indicate that a given title is inaccessible, which is described as Known to lack significant features required for broad accessibility.
This is indicated by using List: 196; Code 09 within a ProductFormFeatureValue element.
Vendors may omit all other accessibility metadata fields.
An excerpt of ONIX indicating an inaccessible product is:
<ProductFormFeature>
<ProductFormFeatureType>09</ProductFormFeatureType>
<ProductFormFeatureValue>09</ProductFormFeatureValue>
</ProductFormFeature>Inaccessible
Not available in ONIX
This information can be retrieved from ONIX code list 81; Code: 01: Audiobook.
This field is true if the XPath returns at least one element for:
//Product/DescriptiveDetail/PrimaryContentType[text()="01"] or
//Product/DescriptiveDetail/ProductContentType[text()="01"]Audiobook: Yes
This information can be retrieved from ONIX code list: 196; Code: 00: Accessibility Summary.
The value can be retrieved using XPath:
Accessibility Summary:
This publication includes markup to enable accessibility and compatibility with assistive technology. Images, audio, and video in the publication are well-described in conformance with WCAG 2.0 A.
If the following XPath returns at least one result:
//Product/DescriptiveDetail/ProductFormFeature[ProductFormFeatureType="09"
and ProductFormFeatureValue="02"]Accessibility Conformance: WCAG-A
If the following XPath returns at least one result:
//Product/DescriptiveDetail/ProductFormFeature[ProductFormFeatureType="09"
and ProductFormFeatureValue="03"] returns at least one resultAccessibility Conformance: WCAG-AA
Not available in ONIX
Not available in ONIX
List: 196; Code: 94: Compliance web page for detailed accessibility information
Or
If a publisher is self-certifying, Code: 96: Publisher’s web page for detailed accessibility information
The value can be retrieve using XPath:
Certifier Report
(Clickable Image to the URI of the report from metadata)
alt-text
Report webpage(Image here of checkmark with clipboard is just for reference feel free to choose your own image)
Or
Certifier Report: Accessibility Report
(Clickable link to the URI of the report from metadata)
Not available in ONIX
For a complete list of ONIX accessibility metadata refer to the crosswalk.