EPUB 3 Overview

W3C Group Note

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Matt Garrish (DAISY Consortium)
Ivan Herman (W3C)
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Garth Conboy (Google Inc.)
Markus Gylling (International Digital Publishing Forum (IDPF))
William McCoy (International Digital Publishing Forum (IDPF))
MURATA Makoto (Keio Advanced Publishing Laboratory and JEPA)
Daniel Weck (DAISY Consortium)
GitHub w3c/epub-specs (pull requests, new issue, open issues)
public-epub-wg@w3.org with subject line [epub-overview-33] … message topic … (archives)


This document provides a starting point for content authors and software developers wishing to understand the EPUB® 3 specifications. It consists entirely of non-normative overview material that describes the features available in EPUB 3.

Status of This Document

This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

This document was published by the EPUB 3 Working Group as a Group Note using the Note track.

Group Notes are not endorsed by W3C nor its Members.

This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

The W3C Patent Policy does not carry any licensing requirements or commitments on this document.

This document is governed by the 2 November 2021 W3C Process Document.

1. Documents

EPUB 3.3 [EPUB-33] is the current version of EPUB 3. It is defined by the following specifications:

Recommendation-track Documents:
Working Group Notes:
  • EPUB Accessibility - EU Accessibility Act Mapping [EPUB-A11Y-EAA-MAPPING]: aims to demonstrate that the technical requirements of the European Accessibility Act related to ebooks are met by the EPUB standard.
  • EPUB Accessibility Techniques 1.1 [EPUB-A11Y-TECH-11]: provides guidance on how to meet the EPUB Accessibility 1.1 [EPUB-A11Y-11] discovery and accessibility requirements for EPUB Publications.
  • EPUB Multiple-Rendition Publications 1.1 [EPUB-MULTI-REND-11]: defines the creation and rendering of EPUB Publications consisting of more than one Rendition.
  • EPUB 3 Structural Semantics Vocabulary 1.1 [EPUB-SSV-11]: defines a set of properties relating to the description of structural semantics of written works.
  • EPUB 3 Text-to-Speech Enhancements 1.0 [EPUB-TTS-10]: describes authoring features and reading system support for improving the voicing of EPUB 3 publications.

This overview document concentrates on the authoring format of EPUB 3.3.

The recommendation-track documents include detailed change logs on the substantive changes since the previous official releases. See the change log for EPUB 3.3, EPUB Reading Systems 3.3, and EPUB Accessibility 1.1, respectively.

2. Features

This section covers the major features of EPUB, including important components and topics that apply to the process of authoring EPUB Publications as a whole.

Figure 1 The following example visually represents the structure of an EPUB publication.
Visual structure of the main constituents of an EPUB Publication
Image description

'EPUB (OCF) Container' as the outer most component which encapsulates the 'EPUB Publication' containing two documents 'Publication Document' and 'Navigation Document' along with a inner component labelled 'Publication Resources' which contains multiple 'Content Documents' (XHTML, SVG), and multiple 'Other resources' (CSS, png, mp3, mov, ...).

2.1 Package Document

Every EPUB Publication is represented by a Package Document. The Package Document specifies all the resources required to render that representation of the content. The Package Document also defines a reading order for linear consumption, and associates metadata and navigation information.

The Package Document defines a layer on top of the traditional structuring of a typical web site to facilitate the authoring of digital publications. A web site, for example, embeds references to its resources within its content, which, while a simple and flexible means of identifying resources, makes it difficult to enumerate all the resources required to render it. In addition, there is no standard way for a web site to define that a sequence of pages make up a larger publication, which is precisely what EPUB's spine element [EPUB-33] does (i.e., it provides an external declarative means to explicitly specify navigation through a collection of documents). Finally, the Package Document defines a standard way to represent metadata globally applicable to a collection of pages.

The Package Document also includes a collection element [EPUB-33], which allows grouping of logically related Publication Resources. This element exists to enable the development of specialized content identification, processing, and rendering features such as the ability to define embedded preview content or assemble an index or dictionary from its constituent XHTML Content Documents.


The collection element is not currently used in any specifications that are actively maintained by the EPUB 3 Working Group.

The Package Document is specified in the dedicated section of [EPUB-33].

2.2 Navigation

2.2.1 Reading Order

A key concept of EPUB is that an EPUB Publication consists of multiple resources that can be completely navigated and consumed by a person or program in some specific order.

Many types of publication have an obvious reading order, or logical progression through their content. A novel is an example of a highly sequential document — it typically has a beginning, middle, and end — but not all publications are so ordered: a cookbook or a collection of photographic images might be considered to be more like a database. All documents do, however, have at least one logical ordering of all their top-level content items, whether by date, topic, location, or some other criteria (e.g., a cookbook is typically arranged by recipe type).

Each EPUB Publication defines at least one such logical ordering of all its top-level content in the spine of the Package Document [EPUB-33]. Each one also defines a declarative table of contents in the EPUB Navigation Document [EPUB-33]. EPUB Publications make these data structures available in a machine-readable way external to the content, simplifying their discovery and use.

EPUB Publications are not limited to the linear ordering of their contents, nor do they preclude linking in arbitrary ways — just like the web, EPUB Publications are built on hypertext — but the basic consumption and navigation can be reliably accomplished in a way that is not true for a set of HTML pages.

2.2.2 Navigation Document

Each EPUB Publication contains a special XHTML Content Document called the EPUB Navigation Document, which uses the [HTML] nav element to define human- and machine-readable navigation information. All Reading Systems make use of the Navigation Document to present a table of contents to their users.

The Navigation Document contains baseline accessibility and navigation support, and features to enhance navigation for all users. Prime among these are support for internationalization (for example, as an XHTML document itself, the Navigation Document natively supports ruby annotations) and support for embedded grammars (MathML and SVG can be included within navigation links).

Note that EPUB Reading Systems are not required to use these advanced XHTML features, such as ruby annotations, when generating a Reading System specific table of contents. However, EPUB Creators may also include the Navigation Document in the spine [EPUB-33] to make use of the richer markup.

Navigation Documents also provide a flexible means of tailoring the navigation display using CSS and the hidden attribute [EPUB-33] while not impacting access to information for accessible Reading Systems.

The structure and semantics of Navigation Documents are defined in the dedicated section of [EPUB-33].

2.3 Metadata

EPUB Publications provide a rich array of options for adding metadata. Each Package Document includes a dedicated metadata section [EPUB-33] for general information about the EPUB Publication, allowing titles, authors, identifiers, and other information about the EPUB Publication to be easily accessed. It also provides the means to attach complete bibliographic records using the link element [EPUB-33].

The Package Document also allows a Unique Identifier to be established for the EPUB Publication using the unique-identifier attribute [EPUB-33].

XHTML Content Documents also include the means of annotating document markup with rich metadata, making them more semantically meaningful and useful both for processing and accessibility purposes. Both RDFa [RDFA-IN-HTML] and Microdata [Microdata] attributes can be used in XHTML Content Documents for that purpose.

2.4 Content Documents

Each EPUB Publication contains one or more EPUB Content Documents, as defined in the dedicated section of [EPUB-33]. These are XHTML or SVG documents that describe the readable content and reference associated media resources (e.g., images, audio, and video clips).

XHTML Content Documents are defined by a profile of [HTML].

2.5 Fixed Layouts

Although EPUB's history is steeped in enabling reflowable content, not all publications lend themselves easily to reflowing. Page-precise layouts are required to meaningfully represent children's books, comics and manga, magazines, and many other content forms.

EPUB 3 includes metadata that allows the creation of fixed-layout XHTML Content Documents [EPUB-33], in addition to existing capabilities for fixed layouts in SVG. This metadata enables the control of the page dimensions [EPUB-33], creating a canvas on which elements can be absolutely positioned.

The metadata does not just flag whether content is to be fixed or reflowed, but also allows EPUB Creators to specify the desired orientation of pages [EPUB-33], when to create synthetic spreads [EPUB-33], and how to position pages [EPUB-33] within those spreads, providing a broad range of control over the presentation of EPUB Publications.

The structure and semantics of EPUB Documents with Fixed Layouts are defined in [EPUB-33].

2.6 Rendering and CSS

A key concept of EPUB is that content presentation adapts to the user, rather than the user having to adapt to a particular presentation of content. HTML was originally designed to support dynamic rendering of structured content, but over time HTML as supported in web browsers has become focused on the needs of web applications, and many popular web sites now have layouts with less flexibility.

EPUB Publications, however, are designed to maximize accessibility for the visually impaired, and Reading Systems typically perform text line layout and pagination on the fly, adapting to the size of the display area, the user's preferred font size, and other environmental factors. This behavior is not guaranteed in EPUB; images, vector graphics, video, and other non-reflowable content might be included, and some Reading Systems might not paginate on the fly, or at all. Nevertheless, supporting dynamic adaptive layout and accessibility has been a primary design consideration throughout the evolution of the EPUB standard.

EPUB Content Documents can reference CSS Style Sheets, allowing EPUB Creators to define the desired rendering properties. EPUB 3 follows support for CSS as defined in the [CSSSnapshot].

EPUB 3 also supports CSS styles that enable both horizontal and vertical layout and both left-to-right and right-to-left writing.

2.7 Multimedia

EPUB 3 supports audio and video embedded in XHTML Content Documents via the [HTML] audio and video elements, inheriting all the functionality and features these elements provide. For more information on audio and video formats, refer to the section on core media types [EPUB-33].

Another key multimedia feature in EPUB 3 is the inclusion of Media Overlay Documents [EPUB-33]. When pre-recorded narration is available for an EPUB Publication, Media Overlays provide the ability to synchronize that audio with the text of a Content Document (see also 4.4 Aural Renditions and Media Overlays).

The structure and semantics of EPUB Documents with Media Overlays are defined in [EPUB-33].

2.8 Fonts

EPUB 3 supports two closely related font formats — OpenType [OpenType] and WOFF [WOFF] [WOFF2] — to accommodate both traditional publishing workflows and emerging web-based workflows. Word processing programs used to create EPUB Publications are likely to have access only to a collection of installed OpenType fonts, for example, whereas web-archival EPUB generators will likely only have access to WOFF resources (which cannot be converted to OpenType without undesirable, and potentially unlicensed, stripping of WOFF metadata).

EPUB 3 also supports both obfuscated and regular font resources for both OpenType and WOFF font formats. Support for obfuscated font resources is required to accommodate font licensing restrictions for many commercially available fonts. See the dedicated section on Font Obfuscation in [EPUB-33] for more details.

2.9 Scripting

EPUB strives to treat content declaratively — as data that can be manipulated, not as programs to be executed — but does support scripting as defined in [HTML] and [SVG] (refer to the section on Scripting [EPUB-33] for more information).

It is important to note, however, that EPUB 3 does not require scripting support in Reading Systems, and scripting might be disabled for security reasons.

EPUB Creators need to be aware that scripting in an EPUB Publication can create security considerations that are different from scripting within a web browser. For example, typical same-origin policies are not applicable to content that has been downloaded to a user's local system. Therefore, it is strongly encouraged that scripting be limited to container constrained contexts, as further described in the section on Container-Constrained Scripts [EPUB-33].

In other words, consider limiting scripting to cases where it is essential to the user experience, since it greatly increases the likelihood that content will not be portable across all Reading Systems and creates barriers to accessibility and content reusability.

2.10 Text-to-speech

EPUB 3 provides the following text-to-speech (TTS) facilities for controlling aspects of speech synthesis, such as pronunciation, prosody, and voice characteristics:

Pronunciation Lexicons

The inclusion of generic pronunciation lexicons using the W3C PLS format [PRONUNCIATION-LEXICON] enables EPUB Creators to provide pronunciation rules that apply to the entire EPUB Publication. Refer to Pronunciation Lexicons [EPUB-TTS-10] for more information.

Inline SSML Phonemes

The incorporation of SSML phonemes functionality [SSML] directly into a EPUB Content Document enables fine-grained pronunciation control, taking precedence over default pronunciation rules and/or referenced pronunciation lexicons (as provided by the PLS format mentioned above). Refer to SSML Attributes [EPUB-TTS-10] for more information.

Note that EPUB Creators may also rely on CSS Speech [CSS-SPEECH-1] properties in their style sheet definitions.

The authoring features for improving the voicing of EPUB 3 publication are described in the separate Working Group Note on Text-to-Speech Enhancements [EPUB-TTS-10].

2.11 Container

An EPUB Publication is transported and interchanged as a single file (a "portable document") that contains the Package Documents, all Content Documents, and all other required resources for processing the Publication. The single-file container format for EPUB is based on the widely adopted ZIP format, and an XML document that identifies the location of the Package Document for the Publication in the ZIP archive is located at a pre-defined location within the archive.

This approach provides a clear contract between any creator of an EPUB Publication and any system which consumes such EPUB Publications, as well as a reliable representation that is independent of network transport or file system specifics.

An EPUB Publication's representation as a container file is specified in the dedicated section of [EPUB-33].

3. Global Language Support

EPUB 3 leverages the features in XHTML, SVG, CSS, or MathML for global language support, and it also relies on [Unicode] for encoding the content. This means that content documents in EPUB 3 have the possibility to use different character sets and express bidirectional text, ruby annotations, or typography for many different languages and cultures. Features have also been added to the various components defined by EPUB 3 to ensure language support.

3.1 Metadata

EPUB 3 supports alternate representations of all text metadata items in the package metadata section to improve global distribution of EPUB Publications. The alternate-script property [EPUB-33] can be combined with the xml:lang attribute to include and identify alternate script renderings of language-specific metadata.

Using this property, a Japanese EPUB Publication could, for example, include an alternate Roman-script representation of the author's name and/or one or more representations of the title in a Romance language.

Text metadata items may also rely on attributes specifying base direction [EPUB-33] that allow for a finer control of bidirectional texts (e.g., titles that combine Latin and Arabic or Hebrew characters).

Finally, the page-progression-direction attribute allows the content flow direction to be globally specified for all Content Documents to facilitate rendering (see the page-progression-direction [EPUB-33]).

3.2 Text-to-speech

EPUB 3's support for PLS documents and SSML attributes increases the pronunciation control that EPUB Creators have over the rendering of any natural language in text-to-speech-enabled Reading Systems. Refer to 2.10 Text-to-speech in the Features section for more information on these capabilities.

3.3 Container

The OCF container format supports UTF-8, allowing for internationalized file and directory naming of content resources.

4. Accessibility

A major goal of EPUB is to facilitate content accessibility, and a variety of features in EPUB 3 support this requirement. This section reviews these features, detailing some established best practices for ensuring that EPUB Publications are accessible where applicable.

EPUB 3 also includes an Accessibility specification [EPUB-A11Y-11] that leverages the extensive work done to make web content accessible in [WCAG21]. The specification defines requirements to produce EPUB Publications that can be accessed by a wide range of users. It is accompanied by a techniques document [EPUB-A11Y-TECH-11] that outlines best practices for meeting these requirements.

It is important to note that while accessibility is important in its own right, accessible content is also more valuable content: an accessible EPUB Publication will be adaptable to more devices and be easier to reuse, in whole or in part, via human and automated workflows. The EPUB Working Group strongly recommends that EPUB Creators ensure that they generate accessible content.

4.1 Navigation

As noted in 2.2.2 Navigation Document above, the navigation features represent a universal and flexible navigation system.

The Navigation Document can also be reused in the body of an EPUB Publication by including it in the spine. To avoid the situation in highly structured documents where it might not be desirable to display the complete table of contents to users in the body of the publication, the display level can be modified using the hidden attribute [EPUB-33]. This attribute is ignored by Reading Systems when they render the table of contents outside the spine (e.g., in their own specialized views), which avoids minimizing the information that is available.

EPUB Creators are also encouraged to supply additional nav elements if their EPUB Publications contain non-structural points of interest, such as figures, tables, etc., to further enhance access to the content.

4.2 Semantic Markup

[HTML] supports a number of elements that make markup more semantically meaningful (e.g., section, nav, and aside). EPUB Creators are encouraged to use these elements, in conjunction with best practices for authoring well-structured web content, when creating EPUB XHTML Content Documents. These additions allow content to be better grouped and defined, both to represent the structure of documents and to facilitate their logical navigation. XHTML Content Documents also natively support the inclusion of ARIA role and state attributes and events, including the dedicated [DPUB-ARIA-1.0] roles, enhancing the ability of Assistive Technologies to interact with the content.

EPUB 3 also includes the epub:type attribute, which allows the inclusion of additional information to any element in an EPUB Content Document to express its purpose and meaning within the work. Refer to the section on Expressing Structural Semantics [EPUB-33] for more information.

4.3 Dynamic Layouts

At its core, EPUB is designed for dynamic layout: content is typically intended to be formatted on the fly rather than being typeset in a paginated manner in advance. This core capability is useful for optimizing rendering onto different-sized device screens or window sizes, and it facilitates and simplifies content accessibility.

While it is possible to incorporate more highly formatted content in EPUB — for example via bitmap images or SVG graphics, or even use of CSS explicit positioning and/or table elements to achieve particular visual layouts — EPUB Creators are strongly discouraged from utilizing such techniques. These techniques are not reliable in EPUB since many Reading Systems render content in a paginated manner rather than creating a single scrolling Viewport and since each Reading System might define its own pagination algorithm. In general, it is preferable to achieve visual richness by using CSS Style Sheets without absolute sizing or positioning.

Editor's note

If and when the WG publishes a fxl accessibility note then it is worth referring to it from here

4.4 Aural Renditions and Media Overlays

Aural renderings of content are important for accessibility and are a desirable feature for many users. A baseline to facilitate aural rendering is to utilize semantic HTML designed for dynamic layout. Refer to 2.10 Text-to-speech for more information on how to use the native facilities that XHTML Content Documents include.

Media Overlays [EPUB-33] provide the ability to synchronize the text and audio content of an EPUB Publication. Beyond benefiting accessibility, overlays have other applications, e.g., synchronizing text and audio as a tool for learning to read.

4.5 Scripting

EPUB 3 adopts a progressive enhancement approach for scripted content, whereby scripting is not allowed to interfere with the integrity of the document (i.e., not result in information loss when scripting is not available). Consequently, although documents that do employ scripting can provide fallbacks [EPUB-33] to further facilitate access to their contents, the documents have to be accessible without them.

EPUB Creators should always implement best practices for accessible scripting in web documents, such as provided in [WAI-ARIA], and reserve the use of scripting for situations in which interactivity is critical to the user experience.

A. EPUB Revision History

A.1 OEB, OCF and EPUB 2: 1999—2010

EPUB has its roots in the interchange format known as the Open EBook Publication Structure (OEBPS). OEBPS 1.0 was approved in 1999 by the Open eBook Forum, an organization that later became the International Digital Publishing Forum (IDPF). 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 renamed EPUB 2.0 in October 2007 and approved in September 2010. This revision consisted of a triumvirate of specifications: Open Package Format (OPF), Open Publication Format (OPF), and OCF. EPUB 2.0.1, which was a maintenance update to the 2.0 specification set, primarily intended to clarify and correct errata in the specifications. See [OPF-201] [OPS-201] [OCF-201].

A.2 EPUB 3.0: 2010

Work on a major revision of the EPUB specifications began in 2010, with the goal of aligning EPUB more closely with HTML, and in the process bringing new, native multimedia features, sophisticated CSS layout rendering and font embedding, scripted interactivity, enhanced global language support, and improved accessibility. A new specification for EPUB Media Overlays was also introduced, allowing for text and audio synchronization in EPUB Publications. To better align the specification names with the standard, the Open Package Format specification was renamed EPUB Publications and the Open Publication Format specification was renamed EPUB Content Documents. The EPUB 3.0 specifications were approved in October 2011. See [EPUBPublications-30] [EPUBContentDocs-30] [OCF-30] [EPUBMediaOverlays-30] [EPUBChanges-30].

A.3 EPUB 3.0.1: 2014

The EPUB 3.0.1 revision was undertaken in 2013-14. Although introducing mostly minor fixes and updates, it did see the integration of Fixed Layout Documents, which give EPUB Creators greater control over presentation when a reflowable EPUB is not suitable for the content. See [EPUBPublications-301] [EPUBContentDocs-301] [OCF-301] [EPUBMediaOverlays-301] [EPUBChanges-301].

A.4 EPUB 3.1: 2017

EPUB 3.1 was the first minor revision of EPUB 3. The goal of this revision was to better align EPUB 3 with current web standards. References to important standards were made undated, meaning that whenever they are updated they are legal to use in EPUB 3 content (e.g., the latest version of HTML is always valid to use; a revision of EPUB is not needed). The use of CSS was also clarified, and the use of EPUB-specific properties reduced.

Many EPUB-specific features were also removed from the standard, in particular content switching, triggers, and bindings. This change necessitated a new Package Document version number. See [EPUB-31] [EPUBPackages-31] [EPUBContentDocs-31] [OCF-31] [EPUBMediaOverlays-31] [EPUBChanges-31]

A.5 EPUB 3.2: 2018

The work on EPUB 3.2 was undertaken shortly after EPUB 3.1 to restore compatibility of content to EPUB 3. The change of version number introduced in EPUB 3.1 meant that EPUB Creators, vendors and Reading System developers would have to produce, distribute and consume two versions of EPUB content, but the costs of this change outweighed the benefits of the new version. EPUB 3.2 instead keeps all the best parts of EPUB 3.1 but deprecates elements instead of removing them so that a new version number is not necessary in the Package Document. See [EPUB-32] [EPUBPackages-32] [EPUBContentDocs-32] [OCF-32] [EPUBMediaOverlays-32] [EPUBChanges-32]

A.6 EPUB 3.3: 2022

The work on EPUB 3.3 [EPUB-33] was undertaken in 2020-21, and is the first version of the EPUB 3 series published as a W3C Recommendation. EPUB 3.3 does not include any significant technical change to, and is strongly backward compatible with, EPUB 3.2. This means that any valid EPUB 3.2 Publication is also a valid EPUB 3.3 Publication.

The documents themselves have been restructured. The primary motivation for this restructuring, as well as an extensive editorial revision, was to make the documents more readable. Also, as part of the thorough testing regime developed by the W3C EPUB 3 Working Group, this restructuring led to the separation of Recommendations and Working Group Notes (see also the detailed list of documents ). Features specified in the Recommendations are thoroughly tested, are widely implemented in Reading Systems, and they can be considered as interoperable. On the other hand, features specified in Working Group Notes, although they may have some authoring uptakes, still lack support in Reading Systems; as a result, these technologies should not yet be considered stable and interoperable.

The separate section in [EPUB-33] provides a more detailed overview of the changes.

B. References

B.1 Informative references

CSS Speech Module. Daniel Weck. W3C. 10 March 2020. W3C Candidate Recommendation. URL: https://www.w3.org/TR/css-speech-1/
CSS Snapshot. URL: https://www.w3.org/TR/CSS/
Digital Publishing WAI-ARIA Module 1.0. Matt Garrish; Tzviya Siegman; Markus Gylling; Shane McCarron. W3C. 14 December 2017. W3C Recommendation. URL: https://www.w3.org/TR/dpub-aria-1.0/
EPUB 3.1. Markus Gylling; Tzviya Siegman; Matt Garrish. IDPF. 05 January 2017. URL: http://idpf.org/epub/31/spec/epub-spec-20170105.html
EPUB 3.2. Matt Garrish; Dave Cramer. EPUB 3 Community Group. 08 May 2019. URL: https://www.w3.org/publishing/epub32/epub-spec.html
EPUB 3.3. Matt Garrish; Ivan Herman; Dave Cramer. W3C. 4 April 2022. W3C Working Draft. URL: https://www.w3.org/TR/epub-33/
EPUB Accessibility 1.1. Matt Garrish; George Kerscher; Charles LaPierre; Gregorio Pellegrino; Avneesh Singh. W3C. 1 April 2022. W3C Working Draft. URL: https://www.w3.org/TR/epub-a11y-11/
EPUB Accessibility - EU Accessibility Act Mapping. Cristina Mussinelli; Luc Audrain; Gregorio Pellegrino. W3C. 31 March 2022. W3C Working Group Note. URL: https://www.w3.org/TR/epub-a11y-eaa-mapping/
EPUB Accessibility Techniques 1.1. Matt Garrish; George Kerscher; Charles LaPierre; Gregorio Pellegrino; Avneesh Singh. W3C. 31 March 2022. W3C Working Group Note. URL: https://www.w3.org/TR/epub-a11y-tech-11/
EPUB 3 Multiple-Rendition Publications 1.1. Matt Garrish. W3C. 31 March 2022. W3C Working Group Note. URL: https://www.w3.org/TR/epub-multi-rend-11/
EPUB Reading Systems 3.3. Matt Garrish; Ivan Herman; Dave Cramer. W3C. 4 April 2022. W3C Working Draft. URL: https://www.w3.org/TR/epub-rs-33/
EPUB 3 Structural Semantics Vocabulary 1.1. Ivan Herman; Matt Garrish. W3C. 31 March 2022. W3C Working Group Note. URL: https://www.w3.org/TR/epub-ssv-11/
EPUB 3 Text-to-Speech Enhancements 1.0. Matt Garrish. W3C. 31 March 2022. W3C Working Group Note. URL: https://www.w3.org/TR/epub-tts-10/
EPUB 3 Changes from 2.0.1. William McCoy; Markus Gylling. IDPF. 11 October 2011. URL: http://idpf.org/epub/30/spec/epub30-changes-20111011.html
EPUB 3.0.1 Changes from 3.0. Markus Gylling; Matt Garrish. IDPF. 26 June 2014. URL: http://idpf.org/epub/301/spec/epub-changes-20140626.html
EPUB 3.1 Changes from 3.0.1. Markus Gylling; Matt Garrish. IDPF. 05 January 2017. URL: http://idpf.org/epub/31/spec/epub-changes-20170105.html
EPUB 3.2 Changes. Matt Garrish; Dave Cramer. EPUB 3 Community Group. 08 May 2019. URL: https://www.w3.org/publishing/epub32/epub-changes.html
EPUB Content Documents 3.0. Markus Gylling; William McCoy; Elika J. Etimad; Matt Garrish. IDPF. 11 October 2011. URL: http://idpf.org/epub/30/spec/epub30-contentdocs-20111011.html
EPUB Content Documents 3.0.1. Markus Gylling; William McCoy; Elika J. Etimad; Matt Garrish. IDPF. 26 June 2014. URL: http://idpf.org/epub/301/spec/epub-contentdocs-20140626.html
EPUB Content Documents 3.1. Markus Gylling; William McCoy; Dave Cramer; Elika J. Etimad; Matt Garrish. IDPF. 05 January 2017. URL: http://idpf.org/epub/31/spec/epub-contentdocs-20170105.html
EPUB Content Documents 3.2. Dave Cramer; Matt Garrish. EPUB 3 Community Group. 08 May 2019. URL: https://www.w3.org/publishing/epub32/epub-contentdocs.html
EPUB Media Overlays 3.0. Marisa DeMeglio; Daniel Weck. IDPF. 11 October 2011. URL: http://idpf.org/epub/30/spec/epub30-mediaoverlays-20111011.html
EPUB Media Overlays 3.0.1. Marisa DeMeglio; Daniel Weck. IDPF. 26 June 2014. URL: http://idpf.org/epub/301/spec/epub-mediaoverlays-20140626.html
EPUB Media Overlays 3.1. Marisa DeMeglio; Daniel Weck. IDPF. 05 January 2017. URL: http://idpf.org/epub/31/spec/epub-mediaoverlays-20170105.html
EPUB Media Overlays 3.2. Marisa DeMeglio; Daniel Weck. EPUB 3 Community Group. 08 May 2019. URL: https://www.w3.org/publishing/epub32/epub-mediaoverlays.html
EPUB Packages 3.1. Markus Gylling; William McCoy; Matt Garrish. IDPF. 05 January 2017. URL: http://idpf.org/epub/31/spec/epub-packages-20170105.html
EPUB Packages 3.2. Matt Garrish; Dave Cramer. EPUB 3 Community Group. 08 May 2019. URL: https://www.w3.org/publishing/epub32/epub-packages.html
EPUB Publications 3.0. Markus Gylling; William McCoy; Matt Garrish. IDPF. 11 October 2011. URL: http://idpf.org/epub/30/spec/epub30-publications-20111011.html
EPUB Publications 3.0.1. Markus Gylling; William McCoy; Matt Garrish. IDPF. 26 June 2014. URL: http://idpf.org/epub/301/spec/epub-publications-20140626.html
HTML Standard. Anne van Kesteren; Domenic Denicola; Ian Hickson; Philip Jägenstedt; Simon Pieters. WHATWG. Living Standard. URL: https://html.spec.whatwg.org/multipage/
HTML Microdata. Charles 'chaals' (McCathie) Nevile; Dan Brickley; Ian Hickson. W3C. 28 January 2021. W3C Working Group Note. URL: https://www.w3.org/TR/microdata/
EPUB Open Container Format (OCF) 2.0.1. IDPF. 04 September 2010. URL: http://www.idpf.org/epub/20/spec/OCF_2.0.1_draft.doc
EPUB Open Container Format (OCF) 3.0. James Pritchett; Markus Gylling. IDPF. 11 October 2011. URL: http://idpf.org/epub/30/spec/epub30-ocf-20111011.html
EPUB Open Container Format (OCF) 3.0.1. James Pritchett; Markus Gylling. IDPF. 26 June 2014. URL: http://idpf.org/epub/301/spec/epub-ocf-20140626.html
Open Container Format (OCF) 3.1. James Pritchett; Markus Gylling. IDPF. 05 January 2017. URL: http://idpf.org/epub/31/spec/epub-ocf-20170105.html
Open Container Format (OCF) 3.2. Garth Conboy. EPUB 3 Community Group. 08 May 2019. URL: https://www.w3.org/publishing/epub32/epub-ocf.html
OpenType specification. Microsoft. URL: http://www.microsoft.com/typography/otspec/default.htm
Open Packaging Format 2.0.1. IDPF. 04 September 2010. URL: http://www.idpf.org/epub/20/spec/OPF_2.0.1_draft.htm
Open Publication Structure 2.0.1. IDPF. 04 September 2010. URL: http://www.idpf.org/epub/20/spec/OPS_2.0.1_draft.htm
Pronunciation Lexicon Specification (PLS) Version 1.0. Paolo Baggia. W3C. 14 October 2008. W3C Recommendation. URL: https://www.w3.org/TR/pronunciation-lexicon/
HTML+RDFa 1.1 - Second Edition. Manu Sporny. W3C. 17 March 2015. W3C Recommendation. URL: https://www.w3.org/TR/html-rdfa/
Speech Synthesis Markup Language (SSML) Version 1.1. Daniel Burnett; Zhi Wei Shuang. W3C. 7 September 2010. W3C Recommendation. URL: https://www.w3.org/TR/speech-synthesis11/
SVG. W3C. URL: https://www.w3.org/TR/SVG/
The Unicode Standard. Unicode Consortium. URL: https://www.unicode.org/versions/latest/
Accessible Rich Internet Applications (WAI-ARIA) 1.0. James Craig; Michael Cooper et al. W3C. 20 March 2014. W3C Recommendation. URL: https://www.w3.org/TR/wai-aria/
Web Content Accessibility Guidelines (WCAG) 2.1. Andrew Kirkpatrick; Joshue O'Connor; Alastair Campbell; Michael Cooper. W3C. 5 June 2018. W3C Recommendation. URL: https://www.w3.org/TR/WCAG21/
WOFF File Format 1.0. Jonathan Kew; Tal Leming; Erik van Blokland. W3C. 13 December 2012. W3C Recommendation. URL: https://www.w3.org/TR/WOFF/
WOFF File Format 2.0. Vladimir Levantovsky; Raph Levien. W3C. 10 March 2022. W3C Recommendation. URL: https://www.w3.org/TR/WOFF2/