EPUB 3 and Accessibility

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Photo of a stack of books with an eReader on topThe Association of American Publishers recently reported that adult eBook sales overtook the sale of adult hardback sales.  This is big news in the publishing world - the scales are tipping, and we are in the midst of the inevitable rise of the eBook.  Of course, one cannot discuss eBooks without talking about format.

There are many, many different eBook formats - from Amazon's KF8, to Apple's iBook, to PDFs, and everything in between; but the new EPUB3 format is rumored to be "the future of eBooks."  EPUB is an open standard for eBooks created by the International Digital Publishing Forum (IDPF), and is EPUB3 is built on HTML5.

The EPUB 3.0 format was developed to to address criticisms that EPUB was previously unsuitable for publications with special formatting (such as comic books) and lacked specific annotation capabilities and the ability to link to information within the eBook, as well as the need for enhanced language support, metadata support, rich media and interactivity support, enhanced navigation support, enhanced accessibility, and the need to establish a clear relationship to approved national and international standards.

Accessibility has been a major goal of the new version of EPUB, and the IDPF overview of EPUB3 has an entire section dedicated to accessibility specifications covering navigation, semantic markup, dynamic layouts, aural renditions and media overlays, fallbacks, and scripting.

Eric Freese, member of the EPUB3 Working Group lays out the specifications of the EPUB 3 format in his article: "Breaking it Down: the ePub 3 spec."  According to Freese, EPUB2's accessibility features were achieved via a combination of EPUB and DTBook, which provided content to assistive technology for the blind and visually impaired; however, with the capabilities of HTML5, DTBook could be done away with.  EPUB3 files are therefore, technically, "accessible by design."

However, many publishers fail to incorporate accessibility features into their workflows, leaving accessibility features to be retro-fitted to electronic publications by companies that specialize in the retro-fitting process. Unfortunately, such organizations simply cannot keep up with all of the content being produced, and the amount of accessibile content available is severely limited. In the IDPF overview, the EPUB3 workgroup notes "that while accessibility is important in its own right, accessible content is also more valuable content: an accessible Publication will be adaptable to more devices and be easier to reuse, in whole or in part, via human and automated workflows."  It is essential that publishers and other entities producing eBooks realize that accessibility is not only in the interest of consumers who require accessible content, but also to the longevity and adaptability of their content as eReaders, mobile devices, and the means by which we consume electronic media continue to evolve.

The format is already set to be adopted by nearly all popular eReaders, and Amazon is rumored to be investigating offering EPUB on Kindle devices.


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Caitlin is an "Accessibility Decoder" at Deque Systems. She joined the team back in 2011 and has taken on a variety of roles over the years. These days she spends her time exploring the best ways to communicate accessibility ideas and solutions to the general public.


  • Caitlin Cashin Permalink

    Thanks, Matt! Your comment is a great addition to the post, and I really appreciate your input (and thanks for the link to the O’Reilly chapter!).

  • Matt Garrish Permalink

    While definitely true that we need to see a move to a more inclusive publishing model as we go digital — one that accounts for the fact that there is no single universal modality that all readers use to interact with their content — I would only note that a lack of care in terms of production is true of any format.

    Part of what makes EPUB 3 unique, though, is that for the first time publishers do not have to choose between formats (DTBook or HTML4 in EPUB 2) or create separate specialized formats in order to make content accessible for all readers. EPUB 3 subsumes the accessibility features that were present in the DAISY 3 format and expands on them.

    But, as you correctly note, we need to see improvements in content creation tools and processes in order to fully realize this unique opportunity that the rise of the ebook affords.

    Improving workflows and getting information out about accessible content creation requirements and methods is ongoing, by both the IDPF and the DAISY Consortium.

    I would encourage anyone interested creating EPUBs accessibly that they have a look at the free O’Reilly chapter that was released back in February and the active work on accessible markup practices and checklists for EPUB 3 publications (the content guidelines). Links to these and more can be found on the DAISY Web site at http://www.daisy.org/daisy-epub-3-developments

    The folks at EDItEUR have also been working with DAISY and WIPO to tackle these issues, and have made a best practices guide available at

    I appreciate your work in raising this issue, though! We need to make sure that everyone creating content understands that accessibility, like good data or good visual presentation, is something you have to pay attention to and work at.

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