Information technology -- Digital publishing -- EPUB 3.0.1

This specification, EPUB Content Documents 3.0.1, defines profiles of HTML5, SVG, and CSS for use in the context of EPUB® Publications. 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 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. This specification supersedes EPUB Content Documents 3.0 [ContentDocs30]. Refer to [EPUB3Changes] for information on differences between this specification and its predecessor.

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

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Published
Publication Date
18-Feb-2020
Current Stage
6060 - International Standard published
Start Date
02-Jan-2020
Completion Date
19-Feb-2020
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INTERNATIONAL ISO/IEC
STANDARD 23736-3
First edition
2020-02
Information technology — Digital
publishing — EPUB 3.0.1 —
Part 3:
Content documents
Technologies de l'information — Publications numériques — EPUB
3.0.1 —
Partie 3: Documents de contenu
Reference number
ISO/IEC 23736-3:2020(E)
ISO/IEC 2020
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ISO/IEC 23736-3:2020(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 23736-3:2020(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 Content Documents

3.0.1) 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 website.

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 23736-3:2020(E)
EPUB Content Documents 3.0.1
Recommended Specification 26 June 2014
THIS VERSION
http://www.idpf.org/epub/301/spec/epub-contentdocs-20140626.html
LATEST VERSION
http://www.idpf.org/epub3/latest/contentdocs
PREVIOUS VERSION
http://www.idpf.org/epub/301/spec/epub-contentdocs-20140228.html
A diff of changes from the previous version is also available.

Please refer to the errata for this document, which may include some normative corrections.

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
Markus Gylling, International Digital Publishing Forum (IDPF)
William McCoy, International Digital Publishing Forum (IDPF)
Elika J. Etemad, Invited Expert
Matt Garrish, Invited Expert
TABLE OF CONTENTS
1. Overview
1.1. Purpose and Scope
1.2. Relationship to Other Specifications
1.2.1. Relationship to HTML5
1.2.2. Relationship to SVG
1.2.3. Relationship to CSS
1.2.4. Future Maintenance
1.3. Terminology
1.4. Typographic Conventions
1.5. Conformance Statements
1.6. Namespace prefix mappings
2. EPUB Content Documents
2.1. XHTML Content Documents
2.1.1. Content Conformance
2.1.2. Reading System Conformance
2.1.3. HTML5 Extensions
2.1.3.1. Semantic Markup
© ISO/IEC 2020 – All rights reserved 1
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ISO/IEC 23736-3:2020(E)
2.1.3.1.1. Semantic Inflection
2.1.3.1.1.1. Introduction
2.1.3.1.1.2. The epub:type Attribute
2.1.3.1.1.3. Vocabulary Association
2.1.3.1.1.4. Processing Requirements
2.1.3.1.2. Semantic Enrichment
2.1.3.1.2.1. Introduction
2.1.3.1.2.2. Content Conformance
2.1.3.1.2.3. Processing Requirements
2.1.3.2. SSML Attributes
2.1.3.2.1. Overview
2.1.3.2.2. The ssml:ph attribute
2.1.3.2.3. The ssml:alphabet attribute
2.1.3.3. Content Switching
2.1.3.3.1. Introduction
2.1.3.3.2. Definition
2.1.3.3.2.1. The epub:switch Element
2.1.3.3.2.2. The epub:case Element
2.1.3.3.2.3. The epub:default Element
2.1.3.3.3. Processing
2.1.3.4. The epub:trigger Element
2.1.3.5. Alternate Style Tags
2.1.3.6. Custom Attributes
2.1.3.7. The aria-describedat Attribute
2.1.4. HTML5 Deviations and Constraints
2.1.4.1. Embedded MathML
2.1.4.1.1. Introduction
2.1.4.1.2. Content Conformance
2.1.4.1.3. Reading System Conformance
2.1.4.1.4. Alternative Content
2.1.4.2. Embedded SVG
2.1.4.2.1. Embedded SVG and CSS
2.1.4.3. Unicode Restrictions
2.1.4.4. Discouraged Constructs
2.1.4.5. Special Considerations
2.1.4.5.1. The body element
2.2. EPUB Navigation Documents
2.2.1. Introduction
2.2.2. Content Conformance
2.2.3. Reading System Conformance
2.2.4. EPUB Navigation Document Definition
2.2.4.1. The nav Element: Restrictions
2.2.4.2. The nav Element: Types
2.2.4.2.1. The toc nav Element
2.2.4.2.2. The page-list nav Element
2.2.4.2.3. The landmarks nav Element
2.2.4.2.4. Other nav Elements
2.2.4.3. The hidden attribute
2.3. SVG Content Documents
2.3.1. Introduction
2.3.2. Content Conformance
2.3.3. Restrictions on SVG 1.1
2.3.4. Reading System Conformance
2.3.5. Semantic Inflection
2.4. Scripted Content Documents
2.4.1. Scripting Contexts
2.4.2. Content Conformance
2.4.3. Reading System Conformance
2.4.4. Security Considerations
2.4.5. Event Model Considerations
2.5. Fixed-Layout Documents
2.5.1. Introduction
2.5.2. Reading System Conformance
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ISO/IEC 23736-3:2020(E)
2.5.3. Viewport Rendering
2.5.4. Content Dimensions for XHTML and SVG
2.5.4.1. Expressing ICB Dimensions in XHTML
2.5.4.2. Expressing ICB Dimensions in SVG
3. EPUB Style Sheets
3.1. Content Conformance
3.2. Reading System Conformance
3.3. EPUB 3 CSS Profile
3.3.1. CSS 2.1
3.3.2. CSS 2.0
3.3.3. CSS 3.0 Speech
3.3.4. CSS Fonts Level 3
3.3.5. CSS Text Level 3
3.3.6. CSS Text Decoration Level 3
3.3.7. CSS Writing Modes
3.3.8. Selectors
3.3.9. Media Queries
3.3.10. CSS Namespaces
3.3.11. CSS Multi-Column Layout
3.3.12. Ruby Positioning
3.3.13. Display Property Values oeb-page-head and oeb-page-foot [DEPRECATED]
4. PLS Documents
4.1. Overview
4.2. EPUB Publication Conformance
4.3. Content Conformance
4.4. Reading System Conformance
A. JavaScript epubReadingSystem Object
A.1. Syntax
A.2. Description
A.3. Properties
A.4. Methods
A.4.1. hasFeature
A.4.1.1. Syntax
A.4.1.2. Description
A.4.1.3. Features
B. -epub-fullsize-kana Character Mapping Reference
C. Acknowledgements and Contributors
References
› 1 Overview
› 1.1 Purpose and Scope
This section is informative

This specification, EPUB Content Documents 3.0.1, defines profiles of HTML5, SVG, and CSS for

use in the context of EPUB® Publications.

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:
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ISO/IEC 23736-3:2020(E)

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 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.

This specification supersedes EPUB Content Documents 3.0 [ContentDocs30]. Refer to

[EPUB3Changes] for information on differences between this specification and its predecessor.

› 1.2 Relationship to Other Specifications
This section is informative
› 1.2.1 Relationship to HTML5

The XHTML document type defined by this specification is based on W3C [HTML5], and inherits all

definitions of semantics, structure and processing behaviors from the HTML5 specification unless

otherwise specified.

In addition, this specification defines a set of extensions to the W3C HTML5 document model that

Authors may include in XHTML Content Documents.

This specification defines a simplified processing model that does not require Reading Systems to

support scripting, HTML5 forms or the HTML5 DOM. EPUB Reading Systems conformant with this

specification are only required to be able to process a conforming EPUB Content Document. As

support for scripting and HTML5 forms are optional Reading System features, a conformant Reading

System might not be a fully-conformant HTML5 User Agent (i.e., it might not implement the complete

HTML5 processing model).
› 1.2.2 Relationship to SVG

This specification defines a restricted subset of SVG 1.1 to represent vector graphics inline in XHTML

Content Documents and as standalone SVG Content Documents.
› 1.2.3 Relationship to CSS

The CSS profile defined in this specification has CSS 2.1 [CSS2.1] as its baseline. Any CSS Style

Sheet that conforms to CSS 2.1 may be used in the context of an EPUB Publication, except as noted

in CSS 2.1.

This specification also incorporates features defined by CSS3 Modules and introduces EPUB-specific

CSS constructs.
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ISO/IEC 23736-3:2020(E)
› 1.2.4 Future Maintenance

This specification references W3C specifications that are not yet final, and incompatible changes to

them may occur in the future that would cause EPUB 3 Content Documents that were previously

conformant to no longer be conformant to the latest versions of the referenced specifications.

The IDPF anticipates revising this specification if and when such incompatible changes occur,

updating the normative constraints defined herein as necessary.
› 1.3 Terminology
EPUB Publication

A collection of one or more Renditions conforming to this specification and its sibling

specifications , packaged in an EPUB Container.

An EPUB Publication typically represents a single intellectual or artistic work, but this

specification and its sibling specifications do not circumscribe the nature of the content.

Rendition

A logical document entity consisting of a set of interrelated resources representing one

rendering of an EPUB Publication.
Publication Resource

A resource that contains content or instructions that contribute to the logic and rendering of

at least one Rendition of an EPUB Publication. In the absence of this resource, the EPUB

Publication might not render as intended by the Author. Examples of Publication Resources

include a Rendition's Package Document, EPUB Content Document, EPUB Style Sheets,

audio, video, images, embedded fonts and scripts.

With the exception of the Package Document itself, the Publication Resources required to

render a Rendition are listed in that Rendition's manifest [Publications301] and bundled in

the EPUB Container file (unless specified otherwise in Publication Resource Locations

[Publications301] ).

Examples of resources that are not Publication Resources include those identified by the

Package Document link [Publications301] element and those identified in outbound

hyperlinks that resolve outside the EPUB Container (e.g., referenced from an [HTML5] a

element href attribute).
Core Media Type Resource

A Publication Resource that is a Core Media Type and may therefore be included in the

EPUB Publication without the provision of fallbacks [Publications301] .
EPUB Content Document

A Publication Resource that conforms to one of the EPUB Content Document definitions

(XHTML or SVG).

An EPUB Content Document is a Core Media Type, and may therefore be included in the

EPUB Publication without the provision of fallbacks [Publications301] .
XHTML Content Document
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ISO/IEC 23736-3:2020(E)
An EPUB Content Document conforming to the profile of [HTML5] defined in XHTML
Content Documents.
XHTML Content Documents use the XHTML syntax of [HTML5].
SVG Content Document
An EPUB Content Document conforming to the constraints expressed in SVG Content
Documents.
EPUB Navigation Document
A specialization of the XHTML Content Document, containing human- and machine-

readable global navigation information, conforming to the constraints expressed in EPUB

Navigation Documents.
Scripted Content Document

An EPUB Content Document that includes scripting or an XHTML Content Document that

contains HTML5 forms elements.
Refer to Scripted Content Documents for more information.
Top-level Content Document

An EPUB Content Document referenced from the spine, whether directly or via a fallback

chain [Publications301] .
Fixed-Layout Document

An EPUB Content Document directly referenced from the spine that has been designated

pre-paginated in the Package Document, as defined in The rendition:layout Property

[Publications301] .

The dimensions to use for rendering Fixed-Layout Documents are defined in Fixed-Layout

Documents [ContentDocs301] .
Core Media Type

A set of Publication Resource types for which no fallback is required. Refer to Publication

Resources [Publications301] for more information.
Package Document

A Publication Resource carrying bibliographical and structural metadata about a given

Rendition of an EPUB Publication, as defined in Package Documents [Publications301] .

Manifest

A list of all Publication Resources that constitute the given Rendition of a EPUB

Publication.
Refer to manifest [Publications301] for more information.
Spine

An ordered list of Publication Resources, typically EPUB Content Documents, representing

the default reading order of the given Rendition of an EPUB Publication.
Refer to spine [Publications301] for more information.
Text-to-Speech (TTS)
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ISO/IEC 23736-3:2020(E)

The rendering of the textual content of an EPUB Publication as artificial human speech

using a synthesized voice.
EPUB Style Sheet (or Style Sheet)
A CSS Style Sheet conforming to the CSS profile defined in EPUB Style Sheets .
Viewport

The region of an EPUB Reading System in which the content of an EPUB Publication is

rendered visually to a User.
CSS Viewport
A Viewport capable of displaying CSS-styled content.
SVG Viewport
A Viewport capable of displaying SVG images.
EPUB Container (or Container)
The ZIP-based packaging and distribution format for EPUB Publications defined in
[OCF301].
Author

The person(s) or organization responsible for the creation of an EPUB Publication, which is

not necessarily the creator of the content and resources it contains.
User
An individual that consumes an EPUB Publication using an EPUB Reading System.
EPUB Reading System (or Reading System)
A system that processes EPUB Publications for presentation to a User in a manner
conformant with this specification and its sibling specifications .
› 1.4 Typographic Conventions
The following typographic conventions are used in this specification:
markup

All markup (elements, attributes, properties), code (JavaScript, pseudo-code), machine

processable values (string, characters, media types) and file names are in red-orange

monospace font.
markup

Links to markup and code definitions are underlined and in red-orange monospace font. Only

the first instance in each section is linked.
http://www.idpf.org/
URIs are in navy blue monospace font.
hyperlink
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ISO/IEC 23736-3:2020(E)
Hyperlinks are underlined and in blue.
[reference]
Normative and informative references are enclosed in square brackets.
Term
Terms defined in the Terminology are in capital case.
Term

Links to term definitions have a dotted blue underline. Only the first instance in each section is

linked.
Normative element, attribute and property definitions are in blue boxes.
Informative markup examples are in white boxes.
NOTE
Informative notes are in yellow boxes with a "Note" header.
CAUTION
Informative cautionary note are in red boxes with a "Caution" header.
› 1.5 Conformance Statements

The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY,

and OPTIONAL in this document are to be interpreted as described in [RFC2119].

All sections of this specification are normative except where identified by the informative status label

"This section is informative". The application of informative status to sections and appendices applies

to all child content and subsections they may contain.
All examples in this specification are informative.
› 1.6 Namespace prefix mappings

For convenience, the following namespace prefix mappings [XMLNS] are used throughout this

specification:
prefix namespace URI
epub http://www.idpf.org/2007/ops
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ISO/IEC 23736-3:2020(E)
m http://www.w3.org/1998/Math/MathML
pls http://www.w3.org/2005/01/pronunciation-lexicon
ssml http://www.w3.org/2001/10/synthesis
svg http://www.w3.org/2000/svg
› 2 EPUB Content Documents
› 2.1 XHTML Content Documents

This section defines a profile of [HTML5] for creating XHTML Content Documents. An instance of an

XML document that conforms to this profile is a Core Media Type and is referred to in this

specification and its sibling specifications as an XHTML Content Document.

Unless otherwise specified, this specification inherits all definitions of semantics, structure and

processing behaviors from the [HTML5] specification.
CAUTION

The EPUB 3 XHTML Content Document definition references features in the W3C [HTML5]

specification that are still works in progress and may change in incompatible ways. When

utilizing such features, authors should consider the inherent risks in terms of the potential

impact on interoperability and document longevity.
› 2.1.1 Content Conformance
An XHTML Content Document MUST meet all of the following criteria:
Document Properties

It MUST meet the conformance constraints for XML documents defined in XML Conformance

[Publications301] .
It MUST be an [HTML5] document that conforms to the XHTML syntax.

For all document constructs used that are defined by [HTML5], it MUST conform to the

conformance criteria defined for those constructs in that specification, unless explicitly

overridden in HTML5 Deviations and Constraints.

It MAY include extensions to the [HTML5] grammar as defined in HTML5 Extensions, and MUST

conform to all content conformance constraints defined therein.
File Properties
The XHTML Content Document filename SHOULD use the file extension .xhtml.
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ISO/IEC 23736-3:2020(E)
NOTE

All Publication Resources referenced from an XHTML Content Document must conform to the

constraints for Publication Resources defined in EPUB Publication — Content Conformance

[Publications301]
› 2.1.2 Reading System Conformance

A conformant EPUB Reading System MUST meet all of the following criteria for processing XHTML

Content Documents:

Unless explicitly defined by this specification or its sibling specifications as overridden, it MUST

process XHTML Content Documents using semantics defined by the [HTML5] specification and

honor any applicable User Agent conformance constraints expressed therein.

It MUST meet all Reading System conformance criteria defined in HTML5 Extensions.

It MUST recognize and adapt behaviorally to the constraints defined in HTML5 Deviations and

Constraints.

It MUST meet the Reading System conformance criteria defined in Scripted Content Documents

— Reading System Conformance.

It MUST support visual rendering of XHTML Content Documents as defined in EPUB Style

Sheets — Reading System Conformance.

It SHOULD recognize embedded ARIA markup and support exposure of any given ARIA roles,

states and properties to platform accessibility APIs [WAI-ARIA].
› 2.1.3 HTML5 Extensions

This section defines EPUB 3 XHTML Content Document extensions to the underlying [HTML5]

document model.
› 2.1.3.1 Semantic Markup
› 2.1.3.1.1 Semantic Inflection
› 2.1.3.1.1.1 Introduction
This section is informative

Semantic inflection is the process of attaching additional meaning about the specific purpose and/or

nature an element plays in an XHTML Content Document. In the context of EPUB Publications, the

epub:type attribute is typically used to express domain-specific semantics, with the inflection(s) it

carries complementing the underlying [HTML5] host vocabulary. The applied semantics always refine

the meaning of their containing elements, never override their nature (e.g., the attribute can be used

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ISO/IEC 23736-3:2020(E)

to indicate a section is a chapter in a work, but cannot be used to turn p elements into list items to

avoid proper list structures).

Semantic metadata is not intended for human consumption; it instead provides a controlled way for

Reading Systems and other User Agents to learn more about the structure and content of a

document, providing them the opportunity to enhance the reading experience for Users.

This specification defines a method for semantic inflection using the attribute axis: instead of adding

new XML elements to the XHTML Content Document vocabulary, the epub:type attribute can be

appended to existing elements to inflect the desired semantics. A mechanism to identify external

vocabularies that provide controlled values for the attributes is also defined.
› 2.1.3.1.1.2 The epub:type Attribute

The epub:type attribute inflects semantics on the element on which it appears. Its value is one or

more space-separated terms stemming from external vocabularies associated with the document

instance, as defined in Vocabulary Association.

The inflected semantic MUST express a subclass of the semantic of the carrying element. In the case

of semantically neutral elements (such as [HTML5] div and span ), the inflected semantic MUST NOT

attach a meaning that is already conveyed by an existing element (e.g., that a div represents a

paragraph or section). Reading Systems MUST ignore inflected semantics that conflict with the

carrying element.

As the [HTML5] head element is a metadata container for a document, structural semantics

expressed on this element or any descendant of it have no meaning. Reading Systems MUST ignore

such semantics.
NOTE

The epub:type attribute is intended to be functionally equivalent to the W3C Role Attribute

[Role], but with restrictions as specified in Vocabulary Association. The IDPF's intent is to

harmonize this attribute with W3C mechanisms for semantic inflection in a future major

revision of the specification.
Attribute Name
type
Namespace
http://www.idpf.org/2007/ops
Usage
Global attribute. MAY be specified on all elements.
Value

A space-separated list of property [Publications301] values, with restrictions as defined in

Vocabulary Association.
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ISO/IEC 23736-3:2020(E)
› 2.1.3.1.1.3 Vocabulary Association

This specification adopts the vocabulary association mechanisms defined in Vocabulary Association

Mechanisms [Publications301] , with the following modifications:
› Default Vocabulary

The default vocabulary for Content Documents is defined to be the EPUB 3 Structural Semantics

Vocabulary.
› Reserved Prefixes

This specification reserves prefixes that Authors MAY use in the epub:type attribute in the normative

document EPUB Content Documents Reserved Prefixes.
› The prefix Attribute

The prefix attribute definition is unchanged, but the attribute is defined to be in the namespace

http://www.idpf.org/2007/ops when used in EPUB Content Documents.
The prefix attribute is only valid on the [HTML5] root html element.
› Examples

The following example shows the epub:type attribute used to inflect footnote and note reference

semantics. The properties used are defined in the default vocabulary.


1






The following example shows the epub:type attribute used to inflect glossary semantics on an HTML5

definition list. The property used is defined in the default vocabulary.







The following example shows the epub:type attribute used to inflect source publication pagebreak

semantics. The property used is defined in the default vocabulary. (Note that the dc:source

[Publications301] element provides a means of identifying the source publication to which the given

pagination information applies.)
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ISO/IEC 23736-3:2020(E)





› 2.1.3.1.1.4 Processing Requirements
A Reading System MUST process the epub:type attribute as follows:

It MAY associate specialized behaviors with none, some or all of the terms defined in the default

vocabulary.

It MAY associate specialized behaviors with terms given in vocabularies other than the default.

It MUST ignore terms that it does not recognize.

When Reading System behavior associated with a given epub:type value conflicts with behavior

associated with the carrying element, the behavior associated with the element MUST be given

precedence.
› 2.1.3.1.2 Semantic Enrichment
› 2.1.3.1.2.1 Introduction
This section is informative

Unlike semantic inflection, which is about refining the structures within your markup, semantic

enrichment enables the layering of meaning into the content in order to facilitate machine processing.

The [Microdata] and [RDFa11] specifications both define sets of attributes that can be used in XHTML

Content Documents to semantically enrich the content.
› 2.1.3.1.2.2 Content Conformance
A conformant XHTML Content Document MUST meet all of the following criteria:

It MUST allow the use of [Microdata] attributes as defined in that specification.

It MUST allow the use of [RDFa11] attributes as defined in [HTML+RDFa11].
› 2.1.3.1.2.3 Processing Requirements

Reading Systems MAY process [Microdata] and [RDFa11] attributes as defined in their respective

specifications, but such support is OPTIONAL.
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ISO/IEC 23736-3:2020(E)
› 2.1.3.2 SSML Attributes
› 2.1.3.2.1 Overview

The W3C Speech Synthesis Markup Language [SSML] is a language used for assisting Text-to-

Speech (TTS) engines in generating synthetic speech. Although SSML is designed as a standalone

document type, it also defines semantics suitable for use within other host languages.

This specification recasts the SSML 1.1 phoneme element as two attributes — ssml:ph and

ssml:alphabet — and makes them available within EPUB XHTML Content Documents.

Reading Systems with Text-to-Speech (TTS) capabilities SHOULD support the SSML Attributes as

defined below.
NOTE

For more information on EPUB 3 features related to synthetic speech, refer to Text-to-speech

[EPUB3Overview] .
› 2.1.3.2.2 The ssml:ph attribute

The ssml:ph attribute specifies a phonemic/phonetic pronunciation of the text represented by the

element to which the attribute is attached.
Attribute Name
Namespace
http://www.w3.org/2001/10/synthesis
Usage
Global attribute. May be specified on all elements with which a
...

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