EPUB3 Differences from EPUB 2.0.1

Editors Draft IN PROGRESS

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Garth Conboy, eBook Technologies

Markus Gylling, DAISY Consortium

William McCoy, WebPaper LLC

TBD - additional editors

Table of Contents

1. Overview
1.1. Purpose and Scope
1.2. Relationship to Other Specifications
2. Introduction
2.1. EPUB Revision History
2.2. EPUB3 Development Process
3. Changes to EPUB Specification Documents
3.1. Changes in Document Organization
3.2. Modularity and Conformance Requirement Changes
3.3. Changes in Terminology
4. Changes in EPUB Content Documents 3.0
4.1. XHTML5
4.2. New XHTML Constructs
4.3. CSS 2.1
4.4. New CSS Constructs
4.5. SVG
4.6. MathML
4.7. OPS2 Features Removed From EPUB3
4.7.1. DTBook
4.7.2. Inline XML Islands
4.7.3. Others...
5. Changes in EPUB Publications 3.0
5.1. <item> metadata
5.2. Out-of-Line XML Islands Removed
5.3. Tours Removed
5.4. Guide Deprecated
5.5. NCX specification incorporated
5.6. NCX support required by Reading Systems
5.7. Bindings element added
A. Contributors
A.1. Acknowledgements and Contributors

1. Overview

1.1. Purpose and Scope

This document, EPUB3 Differences from EPUB 2.0.1, describes changes made in the third major revision fo EPUB, a digital publication interchange and delivery format based on XML and Web Standards, including some rationale for the changes, and some guidance for content authors and Reading System developers regarding backwards compatibility considerations.

This document is entirely non-normative. The EPUB specification documents should be consulted for definitive information on EPUB3.

This document is meant to be read and understood in concert with the other documents that make up EPUB3. The EPUB3 Overview [EPUB3Overview], which provides an informative overview of EPUB and a roadmap to the rest of the EPUB3 documents, should be read first.

1.2. Relationship to Other Specifications

This specification references and integrates the building-block specifications comprising EPUB3: [Publications3],

EPUB Publications 3.0 [Publications30] EPUB Content Documents 3.0 [ContentDocs30], Open Container Format 3.0 [OCF3], and EPUB Media Overlays 3.0 [Overlays30]. Unless otherwise specified, terms used herein have the meaning defined in these specifications

2. Introduction

EPUB is an interchange and delivery format for digital publications, based on XML and Web Standards. An EPUB Publication can be thought of as a reliable packaging of Web content that represents a digital book, magazine, or other type of publication, and able to distributed for online and offline consumption.

This document, EPUB3 Differences from EPUB 2.0.1, describes changes made in the third major revision of EPUB, including some rationale for the changes, and some guidance for content authors and Reading System developers regarding backwards compatibility considerations.

This document is entirely non-normative. The EPUB specification documents should be consulted for definitive information on EPUB3. TODO: not all EPUB3 changes are yet captured in this document

2.1. EPUB Revision History

EPUB had its roots in the interchange format known as the Open EBook Publication Structure (OEBPS). OEBPS 1.0 was approved by the organization that became the International Digital Publishing Forum (IDPF) in 1999. Subsequent revisions 1.1 and 1.2 were approved by the IDPF in 2001 and 2002 respectively.

It was realized that a need existed for a format standard that could be used for delivery as well as interchange, and work began in late 2005 on a single-file container format for OEPBS, which was approved by the IDPF as the OEBPS Container Format (OCF) in 2006. Work on a 2.0 revision of OEBPS began in parallel which was approved as the renamed EPUB 2.0 in October, 2007, consisting of a triumvirate of specifications: Open Package Format (OPF), Open Publication Format (OPF) together with OCF. EPUB 2.0.1, a minor update to the 2.0 specification set primarily intended to address issues with the specifications, was approved in September, 2010.

2.2.  EPUB3 Development Process

This document is part of EPUB3, which is being developed by the IDPF EPUB Working Group under a charter approved by the IDPF in May, 2010 and is expected to be completed and approved by IDPF by May, 2011.

This document describes the changes in EPUB3 as differences from EPUB 2.0.1. Please consult the EPUB 2.0.1 specifications for differences between that version and earlier versions of EPUB.

3. Changes to EPUB Specification Documents

In addition to significant changes in syntax and semantics, the EPUB3 specifications are structured and named differently than EPUB 2.0.1. The following sections describe the organization of documents relative to content and the specification philosophy regarding modularity and conformance requirements.

3.1. Changes in Document Organization

In order to help those familiar with EPUB 2.0.1 to understand the mapping of information in EPUB3, the following table shows where information in EPUB3 is located in EPUB 2.0.1

Table 3.1. Specification Document Organization

Area EPUB3 Specification EPUB 2.0.1 Specification
Overview EPUB3 Overview (throughout)
Publication-level Specification & Package Docs EPUB Publications 3.0 Open Packaging Format 2.0.1
Content-level Specification EPUB Content Documents 3.0 Open Publication Structure 2.0.1
NCX Documents EPUB Publications 3.0 N/A (referenced as DAISY specification)
Media Overlays EPUB Media Overlays 3.0 N/A
Container packaging EPUB Open Container Format 3.0 Open Container Format 2.0.1
Differences from previous version EPUB3 Differences from EPUB 2.0.1 (throughout)

3.2. Modularity and Conformance Requirement Changes

Initial steps were taken in the EPUB 2 specifications to make each individual specification modular and able to be reused by other applications besides EPUB. EPUB3 attempts to further increase modularity by always being clear when a sub-specification is stating a conformance requirement that is specific to its use by EPUB, rather than being applicable to any conceivable use of the constructs defined by that sub-specification.

As well the level of prose in each specification is less, with additional explanatory material and best practices now centralized in the Overview.

3.3. Changes in Terminology

It was a non-goal for EPUB3 to make gratuitous terminology changes from EPUB 2.0.1. However, the changes in document organization and specification modularity described above did result in a number of consequential changes in terminology. Some of these changes are detailed below.

Table 3.2. Specification Document Organization

EPUB3 Term EPUB 2.0.1 Term
Content Document OPS Content Document
User Agent (in EPUB Content Documents 3.0) Reading System (in OPS 2.0.1)
OCF Processor (in OCF 3.0) Reading System (in OCF 2.0.1)
EPUB Publication (in EPUB Publications 3.0) OPS Publication (in OPF 2.0.1)
XHTML Content Documents XHTML documents

4. Changes in EPUB Content Documents 3.0

EPUB Content Documents 3.0 supersedes Open Publication Structure 2.0.1 (OPS2). However, this EPUB3 specification is drastically different than its predecessor more so than the other two of the "triumvirate" of specifications that comprised EPUB 2.0.1. A major reason for this difference is that EPUB Content Documents 3.0 uses XHTML5 and CSS 2.1 plus select CSS3 properties, whereas OPS2 was based on an explicitly defined subset of XHTML 1.1 profiles and selected style sheet properties from CSS 2. Additional differences derive from new optional constructs and style properties defined in, and from constructs present in OPS2 that are removed from, EPUB Content Documents 3.0.

4.1. XHTML5


4.2. New XHTML Constructs


4.3. CSS 2.1


4.4. New CSS Constructs


4.5. SVG

SVG documents can appear in the spine in EPUB3; i.e., SVG does not need to be nested within an XHTML document.

4.6. MathML

MathML support is new in EPUB3.

4.7. OPS2 Features Removed From EPUB3

4.7.1. DTBook

DAISY DTBook was an alternative syntax to XHTML 1.1 for Content Documents in OPS 2.0.1, in order to provide an option for more semantic, and thus more accessible, content. As XHTML5 includes intrinsic semantic markup capabilities of a similar nature to DTBook, DTBook is no longer an alternative syntax in EPUB3. TODO - more precise ref. to DTBook etc.

4.7.2. Inline XML Islands

Inline XML islands functionality (including "switch", "case", and "default" elements) is no longer part of the specification of Content Docuemnts. Some of the functionality that this mechanism defined in OPS 2.0.1., beyond baseline capabilities of XHTML 1.1, are now part of XHTML5. TODO - be more specific

4.7.3. Others...

TODO - others

5. Changes in EPUB Publications 3.0

EPUB Publications 3.0 ([Publications30]) supersedes Open Packaging Format 2.0.1 ([OPF2]). The subsections below discuss additions and changes in this specification.

5.1. <item> metadata

The <item> element now has optional "rel" and "property" attributes, with the syntax and semantics as defined in RDFa.

5.2. Out-of-Line XML Islands Removed

OPF 2.0.1. specified an optional extension mechanism enabling a spine item to be "custom module" XHTML or arbitrary XML styled with CSS. This feature was not widely adopted by content or Reading Systems, and has been removed from EPUB3, which also defines a more powerful script-based extensibility mechanism. As a result the <item> element no longer has an optional fallback-style attribute.

5.3. Tours Removed

The Package Document schema no longer includes the tours element (which was deprecated in OPF 2.0.1).

5.4. Guide Deprecated

Use of the optional guide element in the Package document has been deprecated in favor of NCX as the unified means of defining declarative navigation for EPUB Publications.

5.5. NCX specification incorporated

In OPF 2.0.1, NCX was defined by reference to the DAISY specification. As the expectation is that EPUB3 will supersede DAISY over time, NCX is now normatively defined as a section of [Publications30] .

5.6. NCX support required by Reading Systems

NCX was mandatory in EPUB2 Publications but supporting it was defined as a "should" for Reading Systems. It is now a "must".

5.7. Bindings element added

A new bindings element provides a means to define script-based handlers for non-standard media types.

Appendix A. Contributors

This appendix is informative

A.1. Acknowledgements and Contributors

This specification has been developed through a cooperative effort, bringing together publishers, vendors, software developers, and experts in the relevant standards.

Version 3.0 of this specification was prepared by the International Digital Publishing Forum’s EPUB Maintenance Working Group. Active members of the working group at the time of publication of revision 2.0.1 were:

TODO 3.0 contributors list

Version 2.0.1 of this specification was prepared by the International Digital Publishing Forum’s EPUB Maintenance Working Group. Active members of the working group at the time of publication of revision 2.0.1 were:

Garth Conboy eBook Technologies Working Group Vice-chair
George Kerscher DAISY Consortium Working Group Chair
Alexis Wiles OverDrive
Alicia Wise Publishers Licensing Society
Amir Moghaddami National Library and Archives of Iran
Andreas Gosling Penguin UK
Andy Williams Cambridge University Press
Anupam Jain Innodata Isogen
Ben Trafford Invited Expert
Benoit Larroque Feedbooks
Bill McCoy Invited Expert
Bill Kasdorf Apex CoVantage
Bob Kasher The BookMasters Group
Brady Duga eBook Technologies
Byron Laws PreMedia Global
Catherine Zekri University of Montreal
Chris Kennedy Pearson Education
Corey Podolsky Entourage Systems Inc.
Cristina Mussinelli AIE
Daihei Shiohama Voyager Japan
Dan Amos DNAML
Dan Galperin Kobo
Dan Kok Crossway Books and Bibles
Dave Cramer Hachette Book Group USA
Dave Gunn RNIB Centre for Accessible Information
David Mandelbaum Barnes&Noble.com
Deidra Roberts World Health Organization
Donald Goyette McGraw-Hill Professional
Eric Freese Aptara
Eric Gold Digital Divide Data
Eric Muller Adobe
Gregory Shepherd Cengage Learning
Guy Fain Crossway Books & Bibles
Hadrien Gardeur Feedbooks
Hisashi Hoda Voyager Japan
Ignacio Fernández Galván
Israel Viente Mendele He-Books
Jim Link Macmillan Publishing Solutions
James MacFarlane Easypress Technologies
Jim Rura Educational Testing Service
John Crossman Benetech
John Prabhu HOV Services
John Rivlin eBook Technologies
John Wait Pearson Education
Jon Noring Invited Expert
Joshua Tallent eBook Architects
Karen Broome Sony
Keith Fahlgren Threepress Consulting
Kenny Johar Vision Australia
Laurie Casey Pearson
Lech Rzedzicki Pearson UK
Liisa McCloy-Kelley Random House
Lindy Humphreys Wiley/ Blackwell Books
Liza Daly Theepress Consulting
Makoto Murata JEPA EPUB Study Group
Marco Croella Simplicissimus Book Farm
Markus Gylling DAISY Consortium
Mattias Karlsson Dolphin Computer Access AB
Michael Smith IDPF
Neil Soiffer Design Science
Noah Genner BookNet Canada
Pat Pagano HarperCollins
Patricia Payton Bowker
Patrick Barry The Educational Company of Ireland
Patrick Berube LEARN
Paul Durrant Durrant Software Limited
Paul Norton Invited Expert
Penelope Reid EPUB User Group (UK)
Perce Huang Far EasTone Telecommunications
Peter Brantley Internet Archive
Peter Sorotokin Adobe
Richard Heiberger HarperCollins Publishers
Richard Kwan Invited Expert
Russell White Random House
Samir Kakar Aptara
Satya Pamarty codeMantra
Scott Cook codeMantra
Sean Ramsey LibreDigital
Siobahn Padgett Hachette BG USA
Steve Arany John Wiley & Sons
Takeshi Kanai Sony
Thad Swiderski LibreDigital
Tim Middleton BookNet Canada
Trudy Conti Follett
Tyler Ruse LibreDigital
William Howard EasyPress Technologies

Version 1.0 of this specification was prepared by the International Digital Publishing Forum’s Unified OEBPS Container Format Working Group. Active members of the working group at the time of publication of revision 1.0 were:

Garth Conboy eBook Technologies Working Group Co-Chair
John Rivlin eBook Technologies Working Group Co-Chair
Jon Ferraiolo IBM Working Group Vice-Chair
Nick Bogaty IDPF Working Group Secretary
Kelley L. Allen Random House
Angel Ancin iRex Technologies
Ryan Bandy Random House
Richard Bellaver Ball State University
Thierry Brethes Mobipocket
Janice Carter Benetech/Bookshare.org
Richard Cohn Adobe Systems Inc.
Neil De Young Hachette Book Group USA
Linh N. Do Random House, Inc.
Geoff Freed WGBH
Liang Gang TriWorks Asia
Peter Ghali Motricity, ereader.com
Markku T. Hakkinen DAISY Consortium
Gillian Harrison NetLibrary
Jonathan Hevenstone Publishing Dimensions
Theresa Horner HarperCollins
Karen Iannone Houghton Mifflin
Claire Israel Simon & Schuster
Mattias Karlsson Dolphin Computer Access
Bill Kasdorf Apex Publishing
George Kerscher DAISY Consortium
Steve Kotrch Simon & Schuster
Bill McCoy Adobe Systems, Inc.
Bill McKenna Follett
Bonnie Melton Houghton Mifflin College Division
Jon Noring OpenReader Consortium Invited Expert
Sayu Osayande Motricity, ereader.com
Lee Passey Invited Expert
Steve Potash OverDrive
Tyler Ruse Codemantra
Mike Smith Harlequin
Kimi Sugeno John Wiley & Sons
Gary Varnell Osoft.com
Xin Wang, Ph.D. ContentGuard, Inc.
Andrew Weinstein Lightning Source
Tom Whitcomb NetLibrary 
Andy Williams Cambridge University Press
Eli Willner Green Point Technology Services


Normative References

[ContentDocs30] EPUB Content Documents 3.0TODO fix link.

[EPUB3Overview] EPUB3 OverviewTODO fix link.

[OCF3] Open Container Format 3.0TODO fix link.

[Overlays30] EPUB Media Overlays 3.0TODO fix link.

[Publications30] EPUB Publications 3.0TODO fix link.