EPUB & DAISY: Standards Under Revision

Original Author(s): Lynn Leith

Written in 2011

  • DAISY experts participating in the revision of both Standards
  • George Kerscher: Secretary General of DAISY Consortium and President of the International Digital Publishing Forum (IDPF)
  • Markus Gylling: Chief Technology Officer for the DAISY Consortium has the lead role in both processes
  • Accessibility will be built into the EPUB 3 standard from the ground up

Both mainstream readers and those who require accessible reading materials will benefit.

The DAISY Standard

  • Part A: Authoring & Interchange (Semantically rich XML modules)
  • Part B: Distribution (integrating with EPUB)

Why Two Parts?

Major browser manufacturers never supported XML natively (everyone thought they would). This complicated matters with DAISY 3 which is XML (display of tables etc. for example). The Consortium's extensive knowledge of XML and how XML is used today will be capitalized on in the development of the DAISY next Standard.

  • Part A: XML - content/master creation, production
  • Part B: HTML - distribution and exchange

EPUB Standard

EPUB logo


.epub is the file extension of an XML format for reflowable digital books and publications. EPUB is composed of three open standards produced by the IDPF (International Digital Publishing Forum) :

  • Open Publication Structure (OPS)
  • Open Packaging Format (OPF)
  • Open Container Format (OCF)

The OPF Specification defines the mechanism by which the various components of an OPS publication are tied together and provides additional structure and semantics to the electronic publication, and uses the NCX as defined in the DAISY Standard. The OCF is a general-purpose container technology, collecting a related set of files into a single-file container; it defines the rules for how to represent a collection of files within a ZIP archive.

DAISY XML = DTBook = OPS, however in OPS there are two possible output options, XML and XHTML. With the current EPUB standard, the master file is not necessarily DTBook as this is one of the two possible vocabularies, XML and XHTML.

"DTBook is an XML vocabulary defined in the DAISY/NISO standard...This vocabulary is specifically designed for eBook content. Many structures not found in XHTML are included: footnotes, sidebars, annotations, page numbers, etc. Identifying the beginning of pages and the number of the page in the original print publication enables direct NCX navigation to the beginning of each page as reflected in the print publication...It is strongly recommended that Content Providers select this XML Preferred Vocabulary for their educational publications and for content that is highly structured...Transforming it into an OPS publication can be accomplished with ease. (EPUB OPS - Open Publication Structure)

XML Workflows Transform to EPUB

  • XML content - DAISY 3
  • Semantics (meaning, relationships) and structure are preserved in the transformation
  • Any XML e.g. DocBook, TEI, can transform using the same techniques
  • All publishers' XML workflows should enable output to EPUB

Transforming DAISY Into EPUB

  • Book semantics integrating in EPUB
  • Audio & text synchronization
  • Rich navigation model
  • Chapter, section, sub-section
  • Page navigation
  • = Fully accessible EPUB

Some Benefits of EPUB

  • EPUB can be converted to other formats like Mobi, Pdb and RTF
  • EPUB is the only format which can currently be run on most devices
  • EPUB is supported on devices like iPad, Sony Reader, Nook, VictorReader Stream
  • The addition of EPUB support in accessible eBook readers provides people who have a print disability with immediate access to the growing eBook market.
  • No transcription is required between the original publication and the consumable, accessible format

DAISY Planet, September 2010: "EPUB and Accessibility"

"Millions of EPUB publications have become available in the last few years with more titles than a blind person 25 years ago would have ever dreamed. The addition of EPUB support in accessible eBook readers provides visually impaired readers with immediate access to the growing eBook market...Print-disabled readers can now open any unprotected EPUB book and experience their preferred combination of audio [synthetic speech] and highlighted text.

From a pure accessibility perspective, EPUB borrows heavily from the DAISY Standards and W3C & Web Accessibility Initiative (WAI) specifications. The text must be present for presentation through synthetic speech, refreshable braille displays, and enlarged character display. Every person over 50 enjoys the benefit of increasing the font size and most systems support sizes that legally blind people can use. Using assistive technology, such as a screen reader, Text-To-Speech (TTS) and refreshable braille can be supported.

All of the features we are beginning to see in EPUB reading systems have been part of DAISY readers for more than a decade. It is wonderful to see accessible features working their way into the mainstream."

DAISYpedia Categories: 

This page was last edited by VLuceno on Friday, April 15, 2016 10:35
Text is available under the terms of the DAISY Consortium Intellectual Property Policy, Licensing, and Working Group Process.