EPUB 3.1 Work Plan

Table of Contents


The EPUB 3.1 revision, run under the 2015 EPUB Working Group charter, is a revision to the EPUB core specifications that will focus on consolidation, simplification, dependency updates as well as addition of a select set of new features (cf. Revision focus areas below).

The specification is intended to reach final recommendation ‒ with supporting tools such as validation and samples/test files in place ‒ no later than Q4 2016.

Revision focus areas

The revision has the following focus areas:

  1. Consolidation

    Consolidate the specification by incorporating applicable modular developments done during 2013-15.

  2. Simplification

    Simplify the specification and the features it defines where possible. Consider deprecation of poorly supported features. (The consolidation and simplification efforts may result in a significant reorganization of the specification documents’ outlines.)

  3. Clarify scripting and interactivity

    To increase the predictability and robustness of content from both authors' and users' standpoints, EPUB should provide clearer rules for scripting support in Reading Systems and content. For example, the ability for content to query Reading Systems on which scripting features it supports/allows, and models for the passing of events between content and Reading Systems, should be fully defined (cf. EPUB 3.1 Feature Requests).

  4. Open Web Platform alignment

    As manifested through IDPF's collaboration with W3C in the Digital Publishing Interest Group, EPUB is on a vector to align further with the Open Web Platform (OWP) to help unify tools and technologies for websites and portable documents. 

    EPUB 3.1 will include work on proposals for synchronization with HTML5, CSS3 and other OWP technologies, metadata expression forms, serialization, and potentially also on server-side manifestations of EPUB. However, the backwards compatibility restrictions and relatively short timeline of EPUB 3.1 make it unrealistic to expect to accomplish all alignment steps that are being envisioned

  5. New features

    The document EPUB 3.1 Feature Requests contains a set of candidate features proposed by the IDPF membership for the EPUB 3.1 revision. While there is no guarantee made in this work plan that any of the proposed features will be added, Working Group members will be given the opportunity to produce proposals for consideration (cf. Modus operandi below). While prioritizing new features to work on, the Working Group is requested to focus on features needed by adjacent publishing domains (for example, journals, comics) as well as improvements to EPUBs accessibility feature set.

Modus operandi

  1. The working group will, as a baseline, produce deliverables that pertain to focus areas 1-4 above.
  2. In addition, Working Group members may produce solution proposals for individual features described in EPUB 3.1 Feature Requests. Each such solution proposal will be reviewed and considered for inclusion in accordance with the revision constraints. Note also that the Working Group may find that there are technical, maturity-, complexity-, rights-related or other hindrances for inclusion during solution research and development. The Working Group shall in such circumstances suggest rejection, deferral or separated modular development of the proposed feature.

Specification drafts and proposals will be hosted at the IDPF GitHub repository.


  1. EPUB 3.1 is intended to be backwards compatible with existing EPUB 3 Reading System implementations to the maximum extent possible. Non-backwards-compatible features (i.e. features without reasonable fallback behaviors) will be added only if there is an extraordinarily good motivation, and extensive stakeholder backing, for doing so.
  2. To avoid an excessively high implementation barrier for EPUB 3.1, new features should be elected for inclusion conservatively, and prioritized based on the actual need for the feature in the ecosystem.


Consolidation of modular specification dependencies

(AHL Region-based Navigation, AHL Multiple Renditions, EPUB Scriptable Components)

starting June 2015

Start of 3.1 core specification development

September 2015

First face-to-face (exact time & location TBD)

October 2015

First WG Draft

January 2016

Second face-to-face (exact time & location TBD)

February/March 2016

Second WG Draft

March 2016

Third WG Draft (feature complete)

May 2016

Proposed Specification

August 2016

Recommended Specification (submission)

October 2016


Working group deliverables are:

Appendix 1. Summary of modular developments 

Following the publication of EPUB 3.0 in the fall of 2011, the EPUB Working Group’s charter was extended to work on modular developments of new features for the EPUB platform.

EPUB Fixed Layout Documents and EPUB Adaptive Layout were considered for inclusion during the EPUB 3.0.1 revision, with the former being integrated.

The EPUB 3.1 revision will, in turn, give consideration to the modular extensions that have been developed since 2013: