Summary

Include accessibility evaluation metadata to enable conformance discovery and provide identification of the evaluator and their credentials.

Examples

Example 1 — Package Document metadata (EPUB 3)

The following example shows a complete set of evaluation metadata for a publication that conforms to the EPUB Accessibility 1.1 specification at WCAG Level AA.

<metadata>
  <meta property="dcterms:conformsTo">
     EPUB Accessibility 1.1 - WCAG 2.0 Level AA
  </meta>
  <meta property="a11y:certifiedBy">Dewey, Checkett and Howe</meta>
  <meta property="a11y:certifierCredential">Certifiably Accessible</meta>
  <link rel="a11y:certifierReport"
        href="https://example.com/reports/a11y/pub.html"/>
  …
</metadata>
Example 2 — Package Document metadata (EPUB 2)

The following example shows how to express evaluation metadata in an EPUB 2 publication using the meta tag's name and content attributes.

<metadata>
  <meta name="dcterms:conformsTo"
        content="EPUB Accessibility 1.1 - WCAG 2.0 Level AA"/>
  <meta name="a11y:certifiedBy" content="Dewey, Checkett and Howe"/>
  <meta name="a11y:certifierCredential" content="Certifiably Accessible"/>
  <meta name="a11y:certifierReport"
        content="https://example.com/reports/a11y/pub.html"/>
  …
</metadata>

Frequently Asked Questions

Does the a11y: prefix have to be declared in the EPUB package document?

Technically, no, but best practice is to always declare the prefix. EPUB has a concept of "reserved prefixes", which are prefixes that can be used without being declared. In practice, however, older versions of the epubcheck validation tool will flag newer predefined prefixes as errors, as they are unaware of newer additions. Declaring the prefix ensures there will not be validation issues.

The a11y: prefix is declared as follows:

<package … prefix="a11y: http://www.idpf.org/epub/vocab/package/a11y/#">

Explanation

Evaluation metadata provides additional information about the individual or organization that has assessed a publication against accessibility standards. It also allows identification of the standard(s) the publication conforms.

All evaluation metadata described in this section with an a11y: prefix are defined in the EPUB Accessibility Vocabulary.

dcterms:conformsTo

An established standard to which the described resource conforms.

When the dcterms:conformsTo property is included in a publication, it indicates that someone has checked and confirmed the publication conforms to a standard. The value of the element is a string or URL that identifies the standard.

In particular, the EPUB Accessibility 1.1 standard uses this property to identify publications that conform to its requirements. The value of the property identifies both the version of the standard the publication conforms to as well as the version and level of WCAG conformance, and must match the following pattern:

EPUB Accessibility 1.1 - WCAG 2.X Level (A|AA|AAA)

The value "2.X" is replaced by the version of WCAG (e.g., 2.0 or 2.1) and "(A|AA|AAA)" is replaced by which of those levels was achieved.

For example, the following values are currently valid to use with this property:

  • EPUB Accessibility 1.1 - WCAG 2.0 Level A
  • EPUB Accessibility 1.1 - WCAG 2.0 Level AA
  • EPUB Accessibility 1.1 - WCAG 2.0 Level AAA
  • EPUB Accessibility 1.1 - WCAG 2.1 Level A
  • EPUB Accessibility 1.1 - WCAG 2.1 Level AA
  • EPUB Accessibility 1.1 - WCAG 2.1 Level AAA

For more information about these conformance values, please refer to the Publication conformance section of the EPUB Accessibility specification.

EPUB 3 usage:
<meta property="dcterms:conformsTo">
  EPUB Accessibility 1.1 - WCAG 2.0 Level AA
</meta>
EPUB 2 usage:
<meta
  name="dcterms:conformsTo"
  content="EPUB Accessibility 1.1 - WCAG 2.0 Level AA"/>
Transitioning from EPUB Accessibility 1.0 to 1.1

The EPUB Accessibility 1.0 specification was developed by the IDPF and used conformance URLs that contained that organization's domain (idpf.org).

Conformance to this version used the package document metadata's link element with idpf.org URLs, like in the following example:

<link
     rel="dcterms:conformsTo"
     href="http://www.idpf.org/epub/a11y/accessibility-20170105.html#wcag-aa"/>

As IDPF no longer exists, the EPUB Working Group decided to drop the use of IDPF URLs for the conformance identifier and move to the string-based identifier system described earlier. While the IDPF URLs remain valid for existing 1.0 content, publishers conforming to the Accessibility 1.0 requirements are encouraged to move to declaring conformance to the new 1.1 specification.

Publications that conform to the EPUB Accessibility 1.0 standard also conform to the 1.1 standard at the same WCAG level.

The following list maps the old identifiers to their replacements:

WCAG 2.0 Level A

  • 1.0 markup:

    <link rel="dcterms:conformsTo"
       href="http://www.idpf.org/epub/a11y/accessibility-20170105.html#wcag-a"/>

  • 1.1 markup:

    <meta property="dcterms:conformsTo">
   EPUB Accessibility 1.1 - WCAG 2.0 Level A
</meta>
WCAG 2.0 Level AA

  • 1.0 markup:

    <link rel="dcterms:conformsTo"
       href="http://www.idpf.org/epub/a11y/accessibility-20170105.html#wcag-aa"/>

  • 1.1 markup:

    <meta property="dcterms:conformsTo">
   EPUB Accessibility 1.1 - WCAG 2.0 Level AA
</meta>
WCAG 2.0 Level AAA

  • 1.0 markup:

    <link rel="dcterms:conformsTo"
       href="http://www.idpf.org/epub/a11y/accessibility-20170105.html#wcag-aaa"/>

  • 1.1 markup:

    <meta property="dcterms:conformsTo">
   EPUB Accessibility 1.1 - WCAG 2.0 Level AAA
</meta>

a11y:certifiedBy

Identifies a party responsible for the testing and certification of the accessibility of an EPUB Publication.

The a11y:certifiedBy property is included in a publication to indicate who reviewed it for accessibility conformance. The EPUB Accessibility specification requires that publishers set this property even when the publication does not meet accessibility requirements.

EPUB 3 usage:
<meta property="a11y:certifiedBy">Dewey, Checkett and Howe</meta>
EPUB 2 usage:
<meta name="a11y:certifiedBy" content="Dewey, Checkett and Howe"/>

a11y:certifierCredential

Identifies a credential or badge that establishes the authority of the party identified in the certifiedBy property to certify content accessible.

The a11y:certifierCredential property identifies a credential the certifier possesses — specifically, one to carry out accessibility evaluations.

The property can either be a text field with the name of the credential held, or it can be a link to a description of the credential.

EPUB 3 usage:
<meta property="a11y:certifierCredential">Certifiably Accessible</meta>
<link rel="a11y:certifierCredential"
  href="https://example.com/a11y/credential"/>
EPUB 2 usage:
<meta name="a11y:certifierCredential" content="Certifiably Accessible"/>
<meta name="a11y:certifierCredential"
  content="https://example.com/a11y/credential"/>

a11y:certifierReport

Provides a link to an accessibility report created by the party identified in the certifiedBy property.

When an accessibility conformance report for the publication is publicly available, publishers can use the a11y:certifierReport property to provide a link to it. Vendors and reading systems can then offer users the option to access this report to discover more information about the title.

EPUB 3 usage:
<link rel="a11y:certifierReport"
  href="https://example.com/reports/a11y/pub.html"/>
EPUB 2 usage:
<meta name="a11y:certifierReport"
  content="https://example.com/reports/a11y/pub.html"/>

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