Wcag Epub

[Peppin Kishore]

Thisspecification specifies content conformance requirements for verifying the accessibility of EPUBPublications. It also specifies accessibility metadata requirements for the discoverability of EPUBpublications.

This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at

Publishers not currently producing accessible content are encouraged to begin updating theirproduction processes to meet the requirements of [epub-a11y-10] while this specification is beingdeveloped. Content that meets the requirements of that version will typically also meet therequirements of this specification with few changes necessary.

A W3C Recommendation is a specification that, after extensive consensus-building, is endorsed by W3C and its Members, and has commitments from Working Group members to royalty-free licensing for implementations. Future updates to this Recommendation may incorporate new features.

This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

The provision of accessibility metadata facilitates informed decisions about the usability of an EPUBpublication. Consumers can review the qualities of the content and decide whether an EPUBpublication is appropriate for their needs, regardless of whether it meets the bar of accessiblecertification. At a minimum, all EPUB publications that conform to this specification meet theaccessibility metadata requirements described in 2. Discoverability.

Although EPUB creators have always beenable to create EPUB publications with a high degree of accessibility, this specification sets formalrequirements for certifying content accessible. These requirements provide EPUB creators a clear setof guidelines to evaluate their content against and allows certification of quality. An accessibleEPUB publication is one that meets the accessibility requirements described in 3. Accessible publications.

The specification also discusses the practice of optimizing EPUB publications for specific readingmodalities. In these cases, the content cannot meet the broad accessibility requirements of thisspecification, but by following its discoverability and reporting requirements EPUB creators canimprove the ability of users to determine if the content still meets their needs. Refer to 4. Optimized publications for more information.

This specification takes an abstract approach to the accessibility requirements for EPUB publications, similar to howWCAG [wcag2] separates its accessibility guidelines from the techniques to achieve them. Thisapproach allows the guidelines to remain stable even as the format evolves.

To facilitate this approach, the companion EPUB AccessibilityTechniques [epub-a11y-tech-11] document outlines conformance techniques. These techniquesexplain how to meet the requirements of this specification for different versions of EPUB.

This specification is also designed to address the accessibility needs of users independent ofwhat languages they read. The same is true for the principles and success criteria defined in[wcag2]. The goal is to ensure that users can fully consume the information of a publicationregardless of their preferred reading modality.

At the same time, the language and writing conventions of the authored text will influence thetechniques necessary to meet the accessibility requirements. EPUB requires support for Unicode text[epub-3], for example, which ensures the correct character data can be used (i.e., EPUB creators do not have to useimages of text). Although this is an important feature, it is often not enough on its own toensure that the text is fully accessible in any given language (e.g., additional informationabout directionality, emphasis, pronunciation, etc. may also be needed).

As a consequence, there may be language- or culture-specific practices for meeting accessibilityrequirements. Whether these practices are defined within this specification and its techniquesor elsewhere (e.g., in WCAG techniques or language-specific best practice recommendations) willdepend on whether the issues are specific to EPUB or broadly affect all web content.

Creators of such EPUB publications should create content in conformance with the accessibility anddiscoverability requirements of this specification. EPUB creators should also upgrade to thelatest version of EPUB to get access to the most advanced accessibility features and techniques.

Note that not all metadata expressions defined in this specification are supported in older versionof EPUB. EPUB 2, in particular, does not support the refines attribute[epub-3]. If EPUB creators cannot avoid expressions that require this attribute, they will have toaccept a certain amount of ambiguity in their statements (i.e., relationships between expression mayonly be apparent by their placement in the package document metadata).

In the case of EPUB, an assistive technology is not always a separate application from a reading system. Readingsystems often integrate features of standalone assistive technologies, such astext-to-speech playback.

The key words MAY, MUST, MUST NOT, OPTIONAL, SHOULD, and SHOULD NOT in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

Ensuring that any interested party can discover the accessible qualities of an EPUB publication istherefore a primary concern. An EPUB publication can have more than one set of sufficient access modes depending on the alternatives provided toenable reading in another mode. For example, if alternative text and descriptions are provided forall the images in a publication, it would have both its default textual and visual sufficient accessmode and a purely textual sufficient access mode.

All EPUB publications MUST include[schema-org] accessibility metadata in the package document that exposes theiraccessible properties, regardless of whether the publications also meet the accessibility or optimizationrequirements.

This specification assumes that conformance and discoverability metadata will be processed andpresented in a human-readable manner, removing the need for a summary unless there is additionalinformation to express. Such processing is not available in all market segments, however,particularly in library systems. Publishers should consider this limitation when decidingwhether to include a summary and what to state in it.

See Discovery Metadata Techniques[epub-a11y-tech-11] for more information on these properties and how to include them indifferent versions of EPUB. See also Includeaccessibility metadata in distribution records [epub-a11y-tech-11] for moreinformation on including accessibility metadata in other formats.

Accessibility metadata can also be included in linked records [epub-3] (i.e., metadata records referenced from linkelements), but the inclusion of such metadata solely in a linked record does not satisfy thediscoverability requirements of this specification.

This section defines how to apply the conformance criteria defined inWCAG to EPUB publications. It also adds additional requirementsunique to EPUB publications, and defines conformance reportingrequirements.

WCAG [wcag2] and its associated techniquesprovide extensive coverage of issues and solutions for web content accessibility, coveringeverything from multimedia to interactive content to structured markup and more. They represent thefoundation that this specification builds upon.

This specification does not repeat the requirements or techniques introduced in those documents, asit risks breaking compatibility between the two standards (e.g., putting guidance out of sync, or inconflict). At the same time, although this specification does not call out those requirements, itdoes not diminish their importance in creating EPUB publications that areaccessible.

The same is true of the techniques in the EPUB Accessibility Techniques document[epub-a11y-tech-11]. It provides coverage of techniques that are unique to EPUB publications, orthat need clarification in the context of an EPUB publication. It does not mean that the rest of theWCAG techniques are not applicable.

As a result, although EPUB creators canread this section without deep knowledge of WCAG conformance, to implement the accessibilityrequirements of this specification requires an understanding of WCAG.

Although conforming at level AAA is not required by this specification, EPUB creators areencouraged to follow the practices detailed in AAA success criteria when producingaccessible EPUB publications.

The reporting flexibility offered by these requirements is to ensure that this specification canbe adapted for use in regions that mandate accessibility but without negating or superseding therequirements in effect in those regions.

This specification sets the baseline requirement to WCAG 2.0 Level A, for example, primarily toprovide EPUB creators backwards compatibility for older content and flexibility to encourageadoption of accessible production where no formal requirements exist. Most accessibilitypractitioners do not recognize this level as providing a high degree of accessibility,however.

Ideally, EPUB creators should try to conform to the latest version of WCAG 2 at Level AA, butlocal and national laws, or procurer or distributor requirements, will define the formalthresholds they must meet.

Examples of legislative requirements for accessibility include the Directive2019/882 in the European Union and Section 508 of the Rehabilitation Act of 1973 in the United States. EPUBpublications will need to meet more than just the basic Level A success criteria to becompliant with these laws.

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