“Comprehensive, accurate, and timely metadata is vital for an efficient industry supply chain.” Graham Bell, Executive Director, EDItEUR

No matter how accessible, or inaccessible, a particular book is, a potential buyer or print-impaired reader needs to be able to select that book with confidence that it will meet their needs. This requires metadata that describes the accessibility features of the ebook. Without that information the reader may not have any clue that a book is accessible. Discoverability is key in the accessibility supply chain and, without it, publishers could lose sales—providing high-quality metadata to retailers has been proven to generate extra sales

Print-impaired readers often need extra information about the accessibility options provided within an ebook. Particular readers have particular requirements, and not every book can provide all possible options—so metadata about the book can help highlight whether the book is accessible to a specific reader.

Publishers are encouraged to provide metadata for the digital content they provide, via ONIX for Books, as well as the EPUB package, via

ONIX for Books

There is a widely-used standard framework called ONIX for Books which provides definitions for the data elements and a standardised way of communicating them. It provides a lingua franca for publishers and retailers, a common lexicon of metadata terms and a standardised data format. Codelist 196 within the ONIX for Books standard focuses entirely on the granular accessibility features that an ebook may have and has 24 different data elements relating to accessibility available to publishers.

You may ask, why add accessibility metadata to ONIX when similar metadata may also be inserted in the EPUB itself? Because print-impaired purchasers need to know before purchase, and even before publication, whether the ebook will meet their needs. If distributed within the standard ONIX metadata, data aggregators, libraries and retailers can be aware of the level of accessibility of a particular ebook before the book itself is available, and can present this information to potential purchasers and readers within their catalogue.

ONIX is:

  • XML-based, so it’s technologically neutral
  • free for publishers and retailers to use
  • international–it can be used with any language or script, and in any business environment
  • equally suitable for both physical and ebooks
  • comprehensive–it covers everything that publishers need to communicate to retailers
  • well-established, but still constantly developing to keep pace with the evolution of the book market
  • able to specify the e-book’s conformance with particular accessibility standards (eg. EPUB Accessibility 1.0) and provide links to further detail

The latest version of List 196  also has accompanying notes to fully explain each data entry point.

ONIX draws a clear line between the accessibility features of an e-book (which might not be shared by other books) and accessibility features provided by the reading system (which might be shared by most books read on that technical platform).

Typical Reading System Features:

  • Onscreen text resizing
  • Basic text to speech functionality
  • Conformation that built in features have not been disabled by the publisher

Typical ebook Features:

  • Navigation facilities
  • Textual descriptions of illustrations
  • Use of typographic designs that don’t present a barrier to dyslexic readers.

These can’t be delivered to the reader by the reading system unless they are present in the e-book itself.

To conform with the Accessibility 1.0 EPUB Specification every EPUB must include various accessibility metadata points. There are also optional additional metadata elements which we encourage publishers to make use of.

Mandatory elements include:

Access Mode—There are four access modes that are typically specified for EPUB Publications:

  • textual—the publication contains text content (headings, paragraphs, etc.).
  • visual—the publication contains visual content such as images, graphics, diagrams, animations and video.
  • auditory—the publication contains auditory content such as standalone audio clips and audio soundtracks for video content.
  • tactile—the publication contains tactile content such as embedded braille and tactile diagrams.

In order for a user to determine whether an EPUB Publication is suitable for their needs, they need to know which of these access modes are required to consume the content. 

 Accessibility FeatureThe EPUB format requires that some accessibility features will always be present (e.g., a table of contents) so make sure you include  these features within the accessibility metadata, as users typically are not aware what features are built into a format. Failing to include relevant features will reduce the discoverability of the publication when users search for specific items.

Accessibility Hazard—You need to declare any potential hazards that the content presents (e.g., flashing, motion simulation, sound). 

Accessibility Summary—A human-readable summary of the overall accessibility, which includes a description of any known deficiencies (e.g., lack of extended descriptions, specific hazards).

A complete description of all the data points and how to use them is available via the EPUB 1.0 Accessibility Specification Techniques document.

The Metadata Workflow

Publishers do not usually hand-type their metadata. Most use an off-the-shelf software solution to manage their metadata and to distribute it in ONIX format to their supply chain  partners. Digital publishers need to make sure that their software vendor supports the use of the accessibility metadata within their system, and that staff are aware of both the range of accessibility optimisations that can be included in their ebooks, how to specify them to third-party vendors, and how those optimisations can be recorded in the metadata.

Retailers, Libraries and Distributors

Libraries and ebook vendors should look for accessibility metadata, and, where it’s provided,  expose it in their catalogues, in a highly accessible way.

Our thanks to Graham Bell and Chris Saynor at EDItEUR for their assistance in providing this information.