W3C Issues a Recommendation for EPUB 3.3

In News by Porter Anderson

Moving from EPUB 3.2 to ePub 3.3 ‘does not require any changes to current publication workflows,’ the W3C working group says.

Image – Getty iStockphoto: Lina Moiseienko

By Porter Anderson, Editor-in-Chief | @Porter_Anderson

Backward-Compatible With ePub 3.2
Today (May 25), the World Wide Web Consortium (WC3) has published the newest version of EPUB as a WC3 recommendation—the equivalent of an international Web standard.

As many professionals in publishing know, “EPUB” defines a distribution and interchange format for digital publications and documents. The format carries a way to represent, package, and encode structured and semantically enhanced Web content, including HTML CSS, SVG, and other resources, for distribution in a single-file container.

EPUB 3.3 is backward-compatible with the previous version, EPUB 3.2, insofar as any EPUB 3.2 document is also valid EPUB 3.3. In other words, moving from EPUB 3.2 to EPUB 3.3 does not require any changes to current publication workflows.

The W3C process of standardization requires a thorough review of the specifications by member-experts, including checking the specification’s impact on implementation for internationalization, security, privacy, accessibility, and conformity to other Web standards.

These reviews led to a number of small but important technical changes such as additional features to address bi-directional text, and more precise specification of security-related details for scripts. The standard also includes detailed guidelines on the possible privacy and security problems.

The working group has also created a comprehensive test suite that systematically tests all normative features of the specification. As a result, the latest version of epubcheck—version 5.0.1 has just been released—is fully compatible with EPUB 3.3. Publishers can use it immediately.

The EPUB 3.3 documents have also undergone “significant improvement,” the team reports, “with editorial changes and reorganizations.” The content specification, which is what publishers, creators, and authors are likely to be most interested in, is now separate from the reading system specification that’s of primary interest for implementers only.

Finally, features that had little adoption, such as multiple rendition, have been removed from the standard text and have been published separately.

Accessibility of EPUB publications was an essential part of the group’s activity. As a result, the EPUB accessibility specification has been updated and, for the first time, is now an integral part of the ePub standard. Furthermore, the EPUB accessibility specification is compatible with the European Accessibility Act the influence of which will be significant on digital publishing in the years to come.

W3C is committed to maintaining the EPUB specification beyond this milestone. A planned dedicated maintenance working group will consider issues such as a possible submission of EPUB 3.3 to ISO to update the current ISO version that’s based on EPUB 3.0.1, or to consider features that were postponed (for example standardization of industry practices to use ePub as a standard format for digital comics). No major technical changes are envisioned at this time.

The team notes that this edition of EPUB is dedicated to Garth Conboy, who was one of the original designers of EPUB, and an initiator of the W3C Working Group, which produced these new specifications..


More from Publishing Perspectives on digital publishing is here, more on the ePub format is here, and more on the World Wide Web Consortium, W3C, is here.

About the Author

Porter Anderson

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Porter Anderson has been named International Trade Press Journalist of the Year in London Book Fair's International Excellence Awards. He is Editor-in-Chief of Publishing Perspectives. He formerly was Associate Editor for The FutureBook at London's The Bookseller. Anderson was for more than a decade a senior producer and anchor with CNN.com, CNN International, and CNN USA. As an arts critic (Fellow, National Critics Institute), he was with The Village Voice, the Dallas Times Herald, and the Tampa Tribune, now the Tampa Bay Times. He co-founded The Hot Sheet, a newsletter for authors, which now is owned and operated by Jane Friedman.