Digital Publishing, EPUB

EPUB 3 Implementation White Paper Now Available

From the IDPF:

As part of the ongoing EPUB 3 Implementation Project the Association for American Publishers (AAP) has made available a white paper that documents several outcomes of the cross-industry initiative, including the top 10 features deemed most critical for immediate implementation by participating publishers and reading system developers, as well as the top 13 tips for content publishers to create accessible EPUB 3 publications. For more information and to download the white paper, visit: .

Digital Publishing, EPUB

What’s Different? Moving from EPUB 2 to EPUB 3 – Navigation

One of the key differences in EPUB 3 is with how navigation is treated within the file.  Gone is the XML based Navigation Control file (NCX) format in favor of a subset of HTML5.  This move helps align EPUB with current web standards. There is no tradeoff with functionality and the HTML5 is less work than the cumbersome XML tagging.

An important concept to grasp is that the new navigational document serves two distinct roles: one is to allow reading systems to render the nav doc as a specialized table of contents and the other is presented within the content.  Although the new nav doc is HTML5 hyperlinks, it is best to keep styling at a bare minimum as reading systems can treat and render the nav document differently.  In some cases, all styling and extraneous tags will be removed.  Although styling cannot be guaranteed in the specialized TOC, reading systems can create a rich user experience.

 Visual Display and Accessibility

It is important to keep accessibility in mind, when considering the visual display of the nav document.  One of the vital roles that the nav doc plays is allowing visually impaired endusers to easily navigate to specific places within a file.  The HTML5 hidden attribute allows content designers to create a clean and light table of contents without removing important navigation queues in the text to speech software.   It is important to include a complete navigation structure that accounts for the depth of a work including all possible levels and entries.

From EPUB 3 Best Practices:

Removing a couple of levels for readability…

        <a href=”s04.xhtml#s190″>190. A Four-Leaved Clover</a>

                   <ol hidden=”hidden”>


                              <a href=”s04.xhtml#s190-1″>I. The Rabbi and the Diadem</a>


By adding the hidden attribute to the ordered list on the third line of the example, all a sighted reader will see is the linkable name of the tale. Someone using an assistive technology will still be able to descend to the part level to move around, however.

To align an EPUB file with the print version of a work, a page-list nav also needs to be included.  Reading systems use the page-list nav to allow end users to jump to a specific page.

To ensure compatibility with older EPUB2 reading systems, a ncx file can be included in the package.



EPUB 3 Best Practices: Optimize Your Digital Books

By Matt Garrish, Markus Gylling

Publisher: O’Reilly Media / Tools of Change

Released: January 2013