Information technology -- Digital publishing -- EPUB 3.0.1

This specification, EPUB Media Overlays 3.0.1, defines a usage of [SMIL] (Synchronized Multimedia Integration Language), the Package Document, the EPUB® Style Sheet, and the EPUB Content Document for representation of audio synchronized with the EPUB Content Document. This specification is one of a family of related specifications that compose EPUB 3, the third major revision of an interchange and delivery format for digital publications based on XML and Web Standards. It is meant to be read and understood in concert with the other specifications that make up EPUB 3: The EPUB 3 Overview [EPUB3Overview], which provides an informative overview of EPUB and a roadmap to the rest of the EPUB 3 documents. The Overview should be read first. EPUB Publications 3.0.1 [Publications301], which defines the semantics and overarching conformance requirements for each Rendition of an EPUB Publication. EPUB Content Documents 3.0.1 [ContentDocs301], which defines profiles of XHTML, SVG and CSS for use in the context of EPUB Publications. EPUB Open Container Format (OCF) 3.0.1 [OCF301], which defines a file format and processing model for encapsulating a set of related resources into a single-file (ZIP) EPUB Container.

Technologies de l'information -- Publications numériques -- EPUB 3.0.1

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18-Feb-2020
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6060 - International Standard published
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02-Jan-2020
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INTERNATIONAL ISO/IEC
STANDARD 23736-1
First edition
2020-02
Information technology — Digital
publishing — EPUB 3.0.1 —
Part 1:
Overview
Technologies de l'information — Publications numériques — EPUB
3.0.1 —
Partie 1: Aperçu général
Reference number
ISO/IEC 23736-1:2020(E)
ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC 23736-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23736-1:2020(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that are

members of ISO or IEC participate in the development of International Standards through technical

committees established by the respective organization to deal with particular fields of technical activity.

ISO and IEC technical committees collaborate in fields of mutual interest. Other international

organizations, governmental and non‐governmental, in liaison with ISO and IEC, also take part in the

work.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of document should be noted (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.

Details of any patent rights identified during the development of the document will be in the

Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC

list of patent declarations received (see http://patents.iec.ch).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the World

Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT),

see www.iso.org/iso/foreword.html.

This document was prepared by the World Wide Web Consortium (W3C) (as EPUB 3 Overview) and

drafted in accordance with its editorial rules. It was adopted, under the JTC 1 PAS procedure, by Joint

Technical Committee ISO/IEC JTC 1, Information technology.

A list of all parts in the ISO/IEC 23736 series can be found on the ISO websitte.e

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO/IEC 2020 – All rights reserved iii
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ISO/IEC 23736-1:2020(E)
EPUB 3 Overview
Recommended Specification 26 June 2014
THIS VERSION
http://www.idpf.org/epub/301/spec/epub-overview-20140626.html
LATEST VERSION
http://www.idpf.org/epub3/latest/overview
PREVIOUS VERSION
http://www.idpf.org/epub/301/spec/epub-overview-20140228.html
A diff of changes from the previous version is also available.
Copyright © 2010-2013 International Digital Publishing Forum™

All rights reserved. This work is protected under Title 17 of the United States Code. Reproduction and

dissemination of this work with changes is prohibited except with the written permission of the International

Digital Publishing Forum (IDPF).
EPUB is a registered trademark of the International Digital Publishing Forum.
Editors
Garth Conboy, Google Inc.
Matt Garrish, Invited Expert
Markus Gylling, International Digital Publishing Forum (IDPF)
William McCoy, International Digital Publishing Forum (IDPF)
MURATA Makoto, JEPA EPUB Study Group
Daniel Weck, DAISY Consortium
This document is informative
TABLE OF CONTENTS
1. Introduction
1.1. Overview
1.2. Roadmap
2. Features
2.1. Package Document
2.2. Navigation
2.2.1. Reading Order
2.2.2. Navigation Document
2.3. Linking
2.4. Metadata
2.5. Content Documents
© ISO/IEC 2020 – All rights reserved 1
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ISO/IEC 23736-1:2020(E)
2.6. Fixed Layouts
2.7. Rendering and CSS
2.8. Multimedia
2.9. Fonts
2.10. Scripting
2.11. Text-to-speech
2.12. Container
3. Global Language Support
3.1. Metadata
3.2. Content Documents
3.3. CSS
3.4. Fonts
3.5. Text-to-speech
3.6. Container
4. Accessibility
4.1. Navigation
4.2. Semantic Markup
4.3. Dynamic Layouts
4.4. Content Descriptions
4.5. Aural Renditions and Media Overlays
4.6. Fallbacks
4.7. Scripting
A. Glossary
B. Acknowledgements and Contributors
B.1. EPUB 3.0
B.2. EPUB 2.0.1
B.3. EPUB 1.0
References
› 1 Introduction
› 1.1 Overview

The EPUB® specification is a distribution and interchange format standard for digital publications and

documents. EPUB defines a means of representing, packaging and encoding structured and

semantically enhanced Web content — including HTML5, CSS, SVG and other resources — for

distribution in a single-file format.

EPUB 3, the third major release of the standard, consists of a set of four specifications, each defining

an important component of an overall EPUB Publication:

EPUB Publications 3.0.1 [Publications301], which defines the semantics and overarching

conformance requirements for each Rendition of an EPUB Publication.

EPUB Content Documents 3.0.1 [ContentDocs301], which defines profiles of XHTML, SVG and

CSS for use in the context of EPUB Publications.
EPUB Open Container Format (OCF) 3.0.1 [OCF301], which defines a file format and

processing model for encapsulating a set of related resources into a single-file (ZIP) EPUB

Container.

EPUB Media Overlays 3.0.1 [MediaOverlays301], which defines a format and a processing

model for synchronization of text and audio.
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ISO/IEC 23736-1:2020(E)

EPUB has been widely adopted as the format for digital books (eBooks), and these new

specifications significantly increase the format's capabilities in order to better support a wider range of

publication requirements, including complex layouts, rich media and interactivity, and global

typography features. The expectation is that EPUB 3 will be utilized for a broad range of content,

including books, magazines and educational, professional and scientific publications.

This document provides a starting point for content authors and software developers wishing to

understand these specifications. It consists entirely of informative overview material, including a

roadmap to the four building-block specification documents that compose EPUB 3.

Another informative document, EPUB 3 Changes from EPUB 2.0.1 [EPUB3Changes], describes

changes in EPUB 3 from the previous version, but is intended primarily for Authors and EPUB

Reading System vendors migrating from EPUB 2.0.1 to EPUB 3 and for those who anticipate

supporting both versions.
› 1.2 Roadmap

This section provides an overview of the EPUB 3 specifications by explaining in brief the components

of an EPUB Publication. Links to additional information within this document and to the specifications

are included.

An EPUB Publication, at its most basic level, is a bundled collection of resources that can be reliably

and predictably ingested by an EPUB Reading System in order to render its contents to a User. Each

EPUB Publication consists of one or renderings of its content, called Renditions.

Some of the resources in the EPUB Container facilitate the discovery and processing of the

Renditions, while others make up the content of the source publication. The latter, EPUB Content

Documents, are described in Content Documents and are fully defined in [ContentDocs301].

An EPUB Publication's resources are typically bundled for distribution as a ZIP-based archive with the

file extension .epub. As conformant ZIP archives, EPUB Publications can be unzipped by many

software programs, simplifying both their production and consumption. The container format is

introduced in Container and defined in [OCF301].

The container format not only provides a means of determining that the zipped content represents an

EPUB Publication (the mimetype file), but also provides a universally-named directory of informative

resources (/META-INF). Key among these is the container.xml file, which directs Reading Systems to

the root files of the available Renditions of the EPUB Publication (their Package Documents).

The Package Document is itself a kind of centralized information source for a given Rendition, storing

metadata about the specific work expressed by the Rendition, providing an exhaustive list of

resources and defining a default reading order. The Package Document is introduced in Package

Document and defined in [Publications301].

The preceding components of an EPUB Publication are not new to EPUB 3, and will be familiar to

anyone who has worked with EPUB Publications before, although they have been changed and

enhanced in this version. A new core addition to EPUB 3, however, is the Media Overlay Document,

which defines a means of synchronizing text and audio playback for a given Rendition. The Overlay

Document is introduced in Multimedia and defined in [MediaOverlays301].

The following example shows the resources a minimal single-Rendition "Hello World" EPUB

Publication might contain:
mimetype
META-INF/container.xml
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ISO/IEC 23736-1:2020(E)
Content/HelloWorld.opf
Content/HelloWorld.xhtml

While conceptually simple, an EPUB Publication is more than just a collection of HTML pages and

dependent assets in a ZIP package as represented in this example. The following sections of this

document delve into more detail about the primary features and functionality that EPUB Publications

provide to enhance the reading experience.
› 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.
› 2.1 Package Document

Each Rendition of an EPUB Publication includes a single Package Document, which specifies all the

resources required to render that Rendition. The Package Document also defines a reading order for

linear consumption, and associates metadata and navigation information for the Rendition.

The Package Document represents a significant improvement on a typical Web site. 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 [Publications301] element 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 [Publications301] element, 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 Package Document and other Rendition-specific constructs are specified in [Publications301].

› 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 collection of photographic images might be

considered to be more like a database. All documents do, however, have at least one logical ordering

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ISO/IEC 23736-1:2020(E)

of all their top-level content items, whether by date, topic, location or some other criteria (e.g., a

cookbook is typically ordered by type of recipe).

Each Rendition of an EPUB Publication defines at least one such logical ordering of all its top-level

content (the spine [Publications301] ), as well as a declarative table of contents (the EPUB Navigation

Document [ContentDocs301]). 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 Rendition of an EPUB Publication contains a special XHTML Content Document called the

EPUB Navigation Document, which uses the HTML5 nav element to define human- and machine-

readable navigation information.

The Navigation Document supersedes the NCX document [OPS2], and the inclusion of NCX

documents is only recommended for forward compatibility in older Reading Systems. The Navigation

Document, while maintaining the baseline accessibility and navigation support and features of the

NCX, introduces new functionality and rendering features to enhance navigation for all Users. Prime

among these are better support for internationalization (as an XHTML5 document itself, the

Navigation Document natively supports ruby annotations) and support for embedded grammars

(MathML and SVG can be included within navigation links).

As XHTML Content Documents, Navigation Documents also provide a flexible means of tailoring the

navigation display using CSS and the hidden attribute [ContentDocs301] while not impacting access

to information for accessible Reading Systems.

The structure and semantics of Navigation Documents are defined in EPUB Navigation Documents

[ContentDocs301] .
› 2.3 Linking

The new EPUB Canonical Fragment Identifier (epubcfi) Specification [EPUBCFI] defines a

standardized method for linking into an EPUB Publication.

Required support for this scheme in Reading Systems means that EPUB now has an interoperable

linking mechanism, one that can, for example, facilitate the sharing of bookmarks and reading

locations across devices.
› 2.4 Metadata

EPUB Publications provide a rich array of options for adding metadata. Each Rendition's Package

Document includes a dedicated metadata section [Publications301] 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 [Publications301] .

The Package Document also allows a Unique Identifier to be established for the EPUB Publication

using the unique-identifier attribute [Publications301] . The required last-modified date in the Package

© ISO/IEC 2020 – All rights reserved 5
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ISO/IEC 23736-1:2020(E)

metadata section can be joined with this identifier to define a Release Identifier, which provides a

means of distinguishing different versions of an EPUB Publication (see Publication Identifiers

[Publications301] ). The Package Identifier addresses the issue of how to release an EPUB

Publication without changing its Unique Identifier while still identifying it as a new version.

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 ( XHTML Semantic Inflection [ContentDocs301] ). Both RDFa and Microdata

attributes can also be used in XHTML Content Documents, enabling content-level metadata

expressions ( XHTML Semantic Enrichment [ContentDocs301] ).
› 2.5 Content Documents

Each Rendition of an EPUB Publication contains one or more EPUB Content Documents, as defined

in [ContentDocs301]. 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 HTML5 that requires the use of XML

serialization [HTML5] in order to ensure that content can be reliably manipulated and rendered. This

profile also adds two additional EPUB-specific language constructs: the epub:type attribute

[ContentDocs301] for element-level metadata and the epub:trigger element [ContentDocs301] for

declaratively associating controls with multimedia elements.

These additions do not affect the ability of an HTML5 User Agent [HTML5] to render XHTML Content

Documents, but EPUB Publications might not render identically in all User Agents depending on their

support.
› 2.6 Fixed Layouts

Although EPUB's history is steeped in enabling reflowable content, not all publications lend

themselves easily to reflowing. Children's books, comics and manga, magazines and many other

content forms require the ability to create page-precise layouts to be represented in a meaningful

fashion.

EPUB 3 includes metadata that allows the creation of fixed-layout XHTML Content Documents

[Publications301] , in addition to existing capabilities for fixed layouts in SVG. This metadata enables

the dimensions of the page [ContentDocs301] to be controlled, 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 Authors to

specify the desired orientation of pages [Publications301] , when to create synthetic spreads

[Publications301] , and how to position pages [Publications301] within those spreads, providing a

broad range of control over the presentation of EPUB Publications.
› 2.7 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 most popular Web sites now have fixed-format

layouts.
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ISO/IEC 23736-1:2020(E)

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 EPUB Style Sheets, allowing Authors to define the desired

rendering properties. EPUB 3 defines a profile of CSS based on CSS 2.1 [CSS2.1] for this purpose,

together with capabilities defined by various CSS3 Modules and several additional properties specific

to EPUB.

CSS3 properties were selected based on their current level of support in Web browsers, but support

for them in Reading Systems and User Agents is not guaranteed (EPUB-defined properties can

similarly be ignored).

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

and right-to-left writing, but Reading Systems might not support all of these capabilities. Reading

Systems might also support different rendering options than the Author intended. Refer to CSS in the

Global Language Support section for more information.

EPUB 3 also supports the ability to include multiple style sheets that allow users, for example, to

select between day/night reading modes or to change the rendering direction of the text. Refer to

Alternate Style Tags [ContentDocs301] for more information.
› 2.8 Multimedia

EPUB 3 supports audio and video embedded in XHTML Content Document via the new [HTML5]

audio and video elements, inheriting all the functionality and features these elements provide. (For

information on supported audio formats, please refer to Core Media Types [Publications301] . For

recommendations on embedding video, refer to Reading System Conformance [Publications301] .)

Another key new multimedia feature in EPUB 3 is the inclusion of Media Overlay Documents

[MediaOverlays301]. When pre-recorded narration is available for a Rendition of an EPUB

Publication, Media Overlays provide the ability to synchronize that audio with the text of a Content

Document (see also Aural Renditions and Media Overlays).
› 2.9 Fonts

EPUB 3 supports two closely-related font formats — OpenType [OpenType] and WOFF [WOFF] — 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.
› 2.10 Scripting
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ISO/IEC 23736-1:2020(E)

EPUB strives to treat content declaratively — as data that can be manipulated, not programs to be

executed — but does support scripting as defined in HTML5 and SVG (refer to Scripted Content

Documents [ContentDocs301] for more information).

It is important to note, however, that scripting support is optional for Reading Systems and might be

disabled for security reasons.

Authors 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

Scripted Content Documents — Content Conformance [ContentDocs301] .

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.
› 2.11 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 [PLS] enables

Authors to provide pronunciation rules that apply to the entire EPUB Publication. Refer to PLS

Documents [ContentDocs301] for more information.
Inline SSML Phonemes

The incorporation of SSML phonemes functionality [SSML] directly into a EPUB Content

Document [ContentDocs301] 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 [ContentDocs301] for more
information.
CSS Speech Features

The inclusion of a select set of features from the CSS 3 Speech Module [CSS3Speech]

(previously known as CSS 2.1 Aural Style Sheets [CSS2.1]) enables Authors to control further

speech synthesis characteristics. Refer to CSS 3.0 Speech [ContentDocs301] for more

information.
› 2.12 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 included Renditions. 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

each Rendition 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.
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ISO/IEC 23736-1:2020(E)

An EPUB Publication's representation as a container file is specified in [OCF301].

› 3 Global 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 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 Romance

languages. Refer to the alternate-script property [Publications301] for more information.

The page-progression-direction attribute also allows the content flow direction to be globally

specified for all Content Documents to facilitate rendering (see the page-progression-direction

[Publications301] ).
› 3.2 Content Documents

XHTML Content Documents leverage the new HTML5 directionality features to improve support for

bidirectional content rendering: the bdi element allows an instance of directional text to be isolated

from the surrounding content, the bdo element allows directionality to be overridden for its child

content and the dir attribute allows the directionality of any element to be explicitly set.

XHTML Content Documents also support ruby annotations for pronunciation support (which makes

them supported in Navigation Document links, as well).

SVG Content Documents support the rendering of bidirectional text, but do not include support for

ruby.
› 3.3 CSS

EPUB 3's support for new CSS3 modules enables typography for many different languages and

cultures. Some specific enhancements include:

support for vertical writing, which also provides Reading Systems the ability to allow users to

toggle direction;
better handling of emphasis, such as the inclusion of bōten;

better control over line breaking, so that breaks can occur at the character level for languages

that do not use spaces to delimit new words; and
better control over hyphenation, to further facilitate line breaking.
› 3.4 Fonts
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ISO/IEC 23736-1:2020(E)

EPUB 3 does not require that Reading Systems come with any particular set of built-in system fonts.

As occurs in Web contexts, Users in a particular locale might have installed fonts that omit characters

required for other locales, and Reading Systems might utilize intrinsic fonts or font engines that do not

utilize operating system installed fonts. As a result, the text content of an EPUB Publication might not

natively render as intended on all Reading Systems.

To address this problem, EPUB 3 supports the embedding of fonts to facilitate the rendering of text

content, and this practice is recommended in order to ensure content is rendered as intended.

Support for embedded fonts also ensures that characters and glyphs unique to an EPUB Publication

can be embedded for proper display.
› 3.5 Text-to-speech

EPUB 3's support for PLS documents and SSML attributes increases the pronunciation control that

Authors have over the rendering of any natural language in text-to-speech-enabled Reading Systems.

Text-to-speech in the Features section for more information on these capabilities.

Refer to

The combination of CSS Speech and inline SSML phonemes also allows fine control over ruby.

› 3.6 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 w
...

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