EPUB Dictionaries and Glossaries

Working Group Draft 20140204

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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

• Jeffrey Alexander, Intangible Press
• Romain Deltour, DAISY Consortium

Authors

• Robert Bolick, Invited Expert
• Karen Broome, Sony Electronics
• Matt Garrish, Invited Expert
• Markus Gylling, International Digital Publishing Forum
• Ori Idan, Helicon Books
• Yasuo Kida, Apple Inc.
• David K. Ream, Leverage Technologies
• Wolfgang Schindler, PONS
• Emmanuelle Seca, Editis

Table of Contents

Editors

Authors

Table of Contents

1. Overview

1.1. Purpose and Scope

1.2. Terminology

1.3. Conformance Statements

2. EPUB Dictionaries and Glossaries Definition

2.1 Introduction

2.2 Content Documents - Dictionaries

2.2.1 The Dictionary Container

2.2.2 The Dictionary Entry

2.2.2.1 article Element As Entry Container

2.2.2.2 Condensed and Detailed Entries

2.2.2.2.1 Introduction

2.2.2.2.2 The Condensed Entry

2.2.2.2.3 Interpreting Condensed Entry and Detailed Entry Markup

2.2.2.2.4 Rendering in Viewports

2.2.3 Headwords

2.2.3.1 Use of dfn Element

2.2.3.2 Canonical Forms of Headwords

2.2.3.2.1 Introduction

2.2.3.2.2 Representing the Canonical Form of a Headword

2.2.3.2.3 Examples

2.2.4 Phonetic Transcriptions

2.2.5 Parts of Speech and Related Grammatical Information

2.2.5.1 Parts of Speech

2.2.5.2 Related Grammatical Information

2.2.6 Etymologies

2.2.7 Meanings and Their Organization in the Entry

2.2.7.1 Introduction

2.2.7.2 Part of Speech Lists

2.2.7.3 Part of Speech Groups

2.2.7.4 Sense Lists

2.2.7.5 Sense Groups

2.2.7.6 Definitions

2.2.7.7 Translations

2.2.7.8 Translation-Related Information

2.2.8 Phrases

2.2.8.1 Introduction

2.2.8.2 Idioms

2.2.8.3 Examples

2.2.8.4 Phrase Lists

2.2.8.5 Phrase Groups

2.2.9 Synonyms and Antonyms

2.2.9.1 Synonym Groups

2.2.9.2 Antonym Groups

2.3 Content Documents - Glossaries

2.3.1 The Glossary Container

2.3.2 Glossary Terms and Definitions

2.3.3 Phonetic Transcriptions in Glossaries

2.4 Search Key Map Documents

2.4.1 Introduction

2.4.2 Content Conformance

2.4.3 Reading System Conformance

2.4.4 Search Key Map Document Definition

2.4.4.1 The search-key-map element

2.4.4.2 The search-key-group element

2.4.4.3 The match element

2.4.4.4 Examples

Example 25: A simple search key map for the headword "get"

Example 26: A search key map for a Japanese dictionary

Example 27: A search key map for a dictionary in simplified Chinese

Example 28: A search key map for the headword "colour"

Example 29: Search key map for a fully inflected French verb

Example 30: Search key map showing that a search key can be mapped to several headwords

2.5 Identification of the Dictionary or Glossary in the Package Document

2.5.1 Dictionary Identification

2.5.1.1 Identification with dc:type

2.5.1.2 Publication consisting of a single EPUB Dictionary

2.5.1.3 Publication consisting of multiple EPUB Dictionaries

2.5.1.4 Additional Dictionary metadata

2.5.1.4.1 Identifying the Dictionary type

2.5.1.4.2 Identifying the Audience

2.5.1.4.3 Identifying Source and Target Languages

2.5.2 Glossary Identification

2.5.3 Manifest item Properties

2.5.4 Package Document Examples

2.5.4.1 Glossary Example

2.5.4.2 Monolingual Dictionary Example

2.5.4.3 Unidirectional Bilingual Dictionary Example

2.5.4.4 Bidirectional Bilingual Dictionary Example

2.5.4.5 Multilingual Dictionary Example

3. Conformance Criteria

3.1 Content Conformance

3.2 Reading System Conformance

Appendix A. Schema for Dictionaries in EPUB Content Documents

Appendix B. Examples

B.1 English Monolingual Dictionary Example

B.2 French-English Bilingual Dictionary Example

B.3 Glossary Example

Appendix C. Contributors and Acknowledgments

IDPF Members

Invited Experts/Observers

References

Normative References

Informative References

1. Overview

1.1. Purpose and Scope

This section is informative

The primary purpose of a dictionary or glossary is to let a user look up an unfamiliar word and retrieve an explanation of its meaning and usage or its translations into another language. This specification provides a means for Authors to represent dictionary and glossary semantics in EPUB Publications [Publications30]. This in turn allows Reading Systems to develop search features that interact with these Publications, notably, lookup search for a word a user selects while reading or inputs into a search field.  Search implementation is aided by a new Core Media Type called the Search Key Map Document, an XML document that gathers all search terms in a central location for fast Reading System access.

Dictionaries vary in terms of style, size, reading level of intended audience, language inclusion, and coverage of general or specialized terminology. The same user may need a specialized dictionary when reading a medical text, a bilingual dictionary when reading a novel in a foreign language, a crossword dictionary when doing crosswords, a thesaurus when writing an essay, and an encyclopedia when reading a history. This specification enables Authors to give users such choice in dictionaries and related reference works,  remedying a situation where users typically only have access to bundled dictionaries.

This specification provides a framework for a rich user experience of dictionary Publications, with a particular focus on word lookup in a cross-publication context. It is designed to enable efficient dictionary search and content retrieval during user access of other EPUB Publications. Moreover, in consideration of the length of many dictionary entries as well as variation in the size of the user’s lookup viewport, dictionary markup allows Authors to tailor an entry specifically for rendering in constrained viewports. Furthermore, optional semantic inflections are designed to encourage Reading System innovation in meeting accessibility needs and making entries easier to read and navigate. The semantic markup defined herein is not, however, intended to serve as an authoring or repository format for dictionaries, and so does not allow for the type of fine-grain distinctions typically required by lexicographers.

Glossaries define a Publication’s key terms in language appropriate to the audience and subject matter. Users need to be able to look up unfamiliar terms and retrieve the valuable, context-specific definitions that glossaries provide, a need that becomes especially acute in educational settings. This specification provides a framework to make such user interaction with glossary content possible. 

1.2. Terminology

Please refer to the EPUB Specifications for definitions of EPUB-specific terminology used in this document.

ancestor context

A property [EPUB301] carried by an ancestor element being semantically inflected [ContentDocs30], either implicitly or explicitly via the epub:type attribute. 

bilingual dictionary

A dictionary in which the meanings of words in a source language are translated into a different target language.  Translation may either be unidirectional (English to Japanese) or bidirectional (both English to Japanese and Japanese to English).

canonical form

The correct spelling of a dictionary headword, unadorned by extra characters or styles conveying additional information about that headword (such as pronunciation symbols, hyphenation points, and the like).

entry

The organizational unit of EPUB Dictionary content, consisting of at least one headword and further information on it. An entry in an EPUB Dictionary is independently distributable, meaning it can be rendered to users outside of its EPUB Dictionary Publication context.

Semantic markup of the entry and its microstructure is detailed in Content Documents - Dictionaries.  

 EPUB Dictionary

Dictionary content within a Rendition of an EPUB Dictionary Publication, consisting of entries whose headwords are in a common language, and accompanied by a Search Key Map Document that links search keys to those entries. An EPUB Dictionary represents a dictionary, encyclopedia, or similarly organized reference work. It can be directly consulted by the user or used by the Reading System to look up terms within any Publication.

Note that an EPUB Dictionary is not a Rendition of the Publication: Renditions are different renderings of the same content, whereas EPUB Dictionaries contain distinct content within a given Rendition.

EPUB Dictionary Publication

An EPUB Publication whose content consists primarily of one or more EPUB Dictionaries. An EPUB Dictionary Publication is identified as such in Package Metadata, as described in section 2.5 Dictionary Identification.

A monolingual EPUB Dictionary Publication will contain only one EPUB Dictionary, whereas a bilingual or multilingual dictionary Publication can contain multiple EPUB Dictionaries. For example: in a French-English bidirectional bilingual dictionary publication, the French-to-English dictionary constitutes one EPUB Dictionary, and the English-to-French dictionary constitutes another EPUB Dictionary. Note that an EPUB Dictionary is not a Rendition of the Publication: Renditions are different renderings of the same content, whereas EPUB Dictionaries contain distinct content within a given Rendition.

EPUB Glossary

All the glossary content within a Rendition of an EPUB Publication and at least one accompanying Search Key Map Document linking search keys to Content Document locations. An EPUB Glossary in a Publication can be directly consulted by the user or used by the Reading System to look up terms within that Publication.

Whether glossary content is organized into one or more sections or distributed throughout the Publication, the entire collection of such content forms the EPUB Glossary.

While the word “glossary” can occur in a Publication’s title, if such a Publication consists primarily of terms and definitions that would be useful outside this Publication, then that Publication is an EPUB Dictionary rather than an EPUB Glossary for purposes of this specification. An EPUB Glossary is always a component of a larger EPUB Publication.

headword

A word or compound word defined, translated, or otherwise treated in an entry.

lookup

A search in a dictionary or glossary for a user-provided word or phrase. The word or phrase can be provided by either selecting text while reading or inputting text into a search field.

The context of a lookup typically differs between dictionaries and glossaries, especially when the word or phrase is provided by selecting text while reading. A glossary can only be used within its Publication, while a dictionary can be used while reading any Publication. In both cases, the dictionary entry or glossary term matching the lookup is retrieved by the Reading System and rendered to the user, typically in a separate viewport.

monolingual dictionary

A dictionary whose headwords, definitions, and other entry content are in the same language.

multilingual dictionary

A dictionary in which the meanings of words in a source language are translated into two or more target languages, and which may cover either one translation direction (English to Japanese and Chinese, for example) or two or more translation directions (English to Japanese and Chinese, Japanese to Chinese and English, and Chinese to Japanese and English).

parent context

A property [EPUB301] carried by the nearest ancestor element being semantically inflected [ContentDocs30], either implicitly or explicitly via the epub:type attribute. 

result form

The form of a search key that is displayed in a result list following a user lookup.

search key

A word or phrase to be matched during a lookup in an EPUB Dictionary or EPUB Glossary. A search key can be mapped to a glossary term, dictionary entry, or location within a dictionary entry using the Search Key Map Document.

Search Key Map Document

An XML document that links search keys to entries in an EPUB Dictionary or to defined terms in an EPUB Glossary.  

source language

The language of entry headwords and phrases.

target language

The language of entry content that translates, defines, or otherwise explains the meanings of headwords and phrases. 

 1.3. 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.

2. EPUB Dictionaries and Glossaries Definition

2.1 Introduction

This section is informative

EPUB Publications conforming to this specification share three key features: semantically marked-up dictionary or glossary content, one or more Search Key Map Documents enabling Reading System search of that content, and metadata identifying dictionary and glossary components. Dictionaries and glossaries differ in how they relate to the EPUB Publication as a whole, however: an EPUB Glossary is always a component of an EPUB Publication, whereas a conforming dictionary is termed an EPUB Dictionary Publication, each Rendition of which consists of one or more EPUB Dictionary components.

Dictionary Content Documents have to conform to a small set of requirements. A collection of entries is marked up with the epub:type dictionary property, the dictionary entry is marked up with article, the HTML element designed for self-contained “independently distributable or reusable” content [HTML5], and the headword is marked up with dfn. This reflects the importance of word lookup during reading as a use case, as a flat, predictable entry structure aids in the retrieval and rendering of dictionary content across Publications. Furthermore, this specification allows Authors to define a condensed entry designed specifically for ease of reading in a lookup viewport [ContentDocs30]; refer to Condensed and Detailed Entries for details.

In addition, optional  epub:type properties can be used to further describe dictionary entries. This allows Reading Systems to enable features such as visual cues and contrast for vision-impaired users, audio cues and announcements for blind users, and entry navigation and readability aids (for example, the ability to skip from the noun to the verb section of an entry, or dynamically collapse or expand a lengthy series of example sentences). Brief markup examples are provided in Content Documents - Dictionaries, but Authors are encouraged to refer to Appendix B for more detailed examples.

Glossary content markup is designed to be both simple and flexible. Authors may organize glossary content into one or more cohesive sections or distribute terms and definitions throughout the Publication (for example, interspersed throughout a textbook or index). This specification maintains backwards-compatibility with the glossary semantics already included in the EPUB3 Structural Semantics Vocabulary [StructureVocab], while refining and expanding on them.

This specification introduces the Search Key Map Document, a new Core Media Type with an XML vocabulary. The Search Key Map Document must be included in an EPUB Dictionary or EPUB Glossary. It gathers together all information required for robust Reading System search: glossary terms or dictionary headwords, inflected forms, idioms, alternate script forms used in search input (e.g. Chinese pinyin), and disambiguation aids shown in search results (e.g. Japanese yomi).

Lastly, metadata is defined for identifying an EPUB Dictionary Publication, describing the components of an EPUB Dictionary or EPUB Glossary, and providing other information such as a dictionary’s source and target languages. When multiple EPUB Dictionaries are present, the collection element is used to group together their components and distinguish them from one another.

2.2 Content Documents - Dictionaries

2.2.1 The Dictionary Container

A body or section element carrying an epub:type dictionary property represents a collection of dictionary entries in an EPUB Dictionary. Every Dictionary Content Document must contain such an element. This element must contain at least one article child element.

A Reading System conforming to this specification must process a dictionary body or section element in accordance with the constraints defined in Content Documents - Dictionaries.

The mechanism for identifying the entire Publication as an EPUB Dictionary Publication is described in Dictionary Identification.

Example 1: a <body> element with epub:type="dictionary", which makes the entire Content Document part of the EPUB Dictionary.

Example 2: a <section> element with epub:type="dictionary". In this case the Author has chosen to include front matter and dictionary entries within the same Content Document.

2.2.2 The Dictionary Entry

2.2.2.1 article Element As Entry Container

An article child of a dictionary section or body element represents a dictionary entry. Dictionary entries are self-contained so that they can be independently rendered in dedicated viewports. It contains at least one headword marked up with dfn along with related information.

Example 3: article elements in an EPUB Dictionary. Note the epub:type dictentry property of article is implied.

2.2.2.2 Condensed and Detailed Entries

2.2.2.2.1 Introduction

This section is informative

To enhance the user’s experience of word lookup during uninterrupted reading, this specification allows dictionary Authors to include Condensed Entries in their EPUB Dictionaries. A Condensed Entry consists of content specially designed for reading in a lookup viewport.  While precise characteristics of the lookup viewport will depend on the Reading System and user preferences, Authors may assume that the lookup viewport is functionally or physically limited when compared to the reading viewport.

A Detailed Entry consists of the full content of the entry, excluding any specially-designed Condensed Entry. In other words, the Detailed Entry is the content rendered when the User browses the Publication. A Condensed Entry is a short entry summary that may be appropriate when viewport size is constrained. 

How each concept corresponds to actual article markup will vary between entries, and at times the Condensed Entry and Detailed Entry will be identical. Guidelines for determining what content to render are supplied in Interpreting Condensed Entry and Detailed Entry Markup and Rendering in Viewports.

The Condensed Entry allows Authors to provide Users a concise set of key meanings during lookup, ones which are more likely to provide the desired meaning without interrupting the reading experience. That said, dictionary Authors also have flexibility in selecting the content to use, and in where and how often to include Condensed Entries. Some dictionaries have entries that could be considered “condensed" generally, while even comprehensive dictionaries contain many short entries. In such cases, there is no need to include a condensed-entry.

However, Authors are encouraged to use this markup whenever condensing the entry for the lookup viewport can provide Users with an improved lookup and reading experience.

There are several editorial approaches that could be taken to creating a Condensed Entry:

• writing a Condensed Entry specifically for this use,
• using the corresponding entry from a smaller dictionary
• selecting key senses from the Detailed Entry
• removing certain elements of the Detailed Entry that are not critical for a quick scan of key meanings during lookup, such as phrase groups (examples and idioms, along with related content), phonetic transcriptions, and etymologies.

2.2.2.2.2 The Condensed Entry

An aside element carrying the epub:type condensed-entry property represents a condensed dictionary entry designed for constrained lookup viewports.  Such an element must have a hidden attribute. This element must be a child of article.

A Reading System conforming to this specification should support rendering of condensed-entry  during lookup as described in Interpreting Condensed Entry and Detailed Entry Markup and Rendering in Viewports.

Authors are strongly encouraged to include Condensed Entries in their EPUB Dictionaries.

Example 4: an extended entry containing a condensed-entry designed for use in a lookup viewport..

Example 5: a short entry that does not need a specially-designed condensed-entry.

2.2.2.2.3 Interpreting Condensed Entry and Detailed Entry Markup

•  If the article element does not have a child aside element carrying an epub:type condensed-entry property, then the article represents both the Condensed Entry and Detailed Entry.
• Otherwise:

• The condensed-entry aside element represents the Condensed Entry.
• The article, excluding the condensed-entry aside, represents the Detailed Entry.

2.2.2.2.4 Rendering in Viewports

When there is an explicit aside element carrying the epub:type condensed-entry property, the Reading System must not render both the Detailed and Condensed Entry in the same viewport.

2.2.3 Headwords 

2.2.3.1 Use of dfn Element 

A headword is a word or compound word defined, translated, or otherwise treated in a dictionary entry. In an EPUB Dictionary a dfn descendant of a dictentry article represents a headword. If, however, a dfn element carries the epub:type idiom property, then it instead represents an idiom, or the defining instance of a phrase; refer to Idioms for details.

An article must contain at least one dfn descendant outside of any condensed-entry aside. If there is a condensed-entry aside , this aside should have at least one dfn element. The dfn is typically associated with additional information.

Each headword in a dictionary entry must be marked up with the dfn element. This applies to all types of headwords typically distinguished by dictionary Authors, such as alternate, variant, run-on, and run-in headwords.

Example 6: an English dictionary entry with the headword “colour” and the alternate headword “color”, both of which are marked up with dfn.

2.2.3.2 Canonical Forms of Headwords

2.2.3.2.1 Introduction

This section is informative

A headword’s canonical form is its correct spelling as defined by the dictionary.

The dfn element’s contents are not always equivalent to the headword’s canonical form. For instance, the Author may include typographic elements such as homograph numbers and syllable markers in dfn to convey additional information to the User.  

This section details how Authors should use the title attribute so that Reading Systems can reliably identify canonical forms for aural rendering and other desired uses.

2.2.3.2.2 Representing the Canonical Form of a Headword

When a dfn element representing a headword has a title attribute, the value of that attribute represents the canonical form of the headword. When no such title attribute is present, the canonical form of the headword is represented by the text content of the dfn element with leading and trailing whitespace trimmed.

The Author must make sure that the canonical form of a headword is represented, either with a title attribute or as the text content of the dfn element.

Reading Systems should identify and use the canonical form when pronouncing or spelling out headwords in an aural rendering.

2.2.3.2.3 Examples

In the Example 6, each dfn element contains the canonical form of the headword and no other content, so use of the title attribute is not necessary.

In the following example, the Author has used the middle dot character (U+00B7) to mark a headword's syllable divisions and a superscript number to indicate that the headword is the first in a series of homographs. As neither mark is actually part of the headwords’ spellings, the Author used the title attribute to supply the canonical forms.

Example 7.

In the following German example of a separable verb, the publisher uses underlining to indicate that a syllable is pronounced with a long vowel, and the “|” character to indicate the part of the word that is put at the end of the sentence. As in the preceding example, the canonical form of the headword must be provided in the title attribute.

Example 8.

2.2.4 Phonetic Transcriptions

A phonetic-transcription represents a phonetic transcription of the pronunciation of a glossary term, dictionary headword, or other component of a dictionary entry. Though a phonetic-transcription of the headword is most typical, it may also relate to a translation, example, or other semantic element.

If phonetic-transcription has one or more preceding dfn siblings, then it relates to the nearest such sibling. Otherwise, it relates to its parent context.

Example 9: English entries with phonetic-transcription written in the International Phonetic Alphabet (IPA). Note that in the “wind” examples, the dfn has an ssml:ph attribute specifying the IPA pronunciation appropriate to the context.

Example 10: a Chinese headword’s phonetic-transcription written in Pinyin. (English translation = “father”.)

2.2.5 Parts of Speech and Related Grammatical Information

2.2.5.1 Parts of Speech

A part-of-speech represents the grammatical function (noun, verb, adjective, etc.) of a headword, either in relation to the entire entry or to a particular set of meanings (such as those contained within a part-of-speech-group).

Grammatical terminology varies across languages. An Author should use the terminology most appropriate for the dictionary’s audience in part-of-speech, but may use any text content. There is not an enumerated list of acceptable values for part-of-speech.

Example 11: an entry with a single part-of-speech value. (Refer to part-of-speech-list for a more complex example.)

2.2.5.2 Related Grammatical Information

A gram-info represents grammatical information related to the headword but distinct from part-of-speech. This could be grammatical information constraining the part of speech generally (such as a note following a noun part-of-speech indicating the headword is always used in the plural) or a particular meaning (such as a note in a sense-group indicating the headword is always plural when expressing that meaning).

Example 12: gram-info following a part-of-speech.

2.2.6 Etymologies

An etymology represents an explanation of the historical origin of a headword.

In aural rendering of a dictionary, Reading Systems may use an audio cue to provide context before reading an etymology.

Example 13: an etymology.

2.2.7 Meanings and Their Organization in the Entry

2.2.7.1 Introduction

This section is informative

Meanings may be organized in complex ways in dictionary entries.  One common approach is to organize the entry hierarchically, where the top level consists of parts of speech (noun, adjective, etc.), each of which can contain a list of senses. Furthermore, each sense may contain a list of phrases pertaining to it. Other approaches are possible as well, such as creating separate entries for different parts of speech, then organizing the entry primarily at the sense level. Whatever an Author’s typical approach may be, entry organization within a given dictionary varies considerably depending on the breadth and depth of information provided on a headword.

Regardless of their organization, entries typically contain definitions, translations, examples, and related information. In contrast to the higher-level organizational units, these semantic elements contain discrete information explaining or illustrating a particular meaning. This specification provides Authors a flexible means of identifying the building blocks of dictionary entries according to the needs of their content, as well as representing the most important types of information contained within structural units.

2.2.7.2 Part of Speech Lists

A part-of-speech-list represents a list of part-of-speech-groups in a dictionary entry.

Use of part-of-speech-list is restricted to the ol element. Each li child of a part-of-speech-list ol has an implied part-of-speech-group epub:type property.

Example 14: a part-of-speech-list with nested sense-lists in a French-English bilingual dictionary. The type attribute of ol specifies that the list will be ordered by uppercase Roman numeral markers. Refer to Appendix B for more detailed examples.

2.2.7.3 Part of Speech Groups

A part-of-speech-group represents a unit that associates a part-of-speech with its related sense-groups and phrase-groups.

The recommended markup for a sequence of part of speech groups is a part-of-speech-list ol. It is preferred for accessibility reasons, and also avoids repetition by implying the part-of-speech-group epub:type property on all its li descendants.

2.2.7.4 Sense Lists

A sense-list represents a list of sense-groups in a dictionary entry.

Use of sense-list is restricted to the ol element. Each li descendant of a sense-list ol has an implied sense-group epub:type property.

Example 15: a sense-list in a French-English bilingual dictionary. As no type attribute is specified on ol,  the list will have the default ordering by decimal numbers. Refer to Appendix B for more detailed examples.

2.2.7.5 Sense Groups

A sense-group represents a unit for organizing information pertaining to a particular meaning of a headword or idiom.

The recommended markup for a sequence of senses is a sense-list ol. It is preferred for accessibility reasons, and also avoids repetition by implying the sense-group epub:type property on all its li descendants.

2.2.7.6 Definitions

A def represents either the definition of a particular meaning of a headword or idiom, or in a bilingual or multilingual dictionary, a short meaning descriptor accompanying particular translations of a headword or idiom. Note that an element carrying the def epub:type property represents only the definition’s content rather than the entire set of associated information (like numeric identifiers, grammatical labels, examples, etc).

When an entry contains multiple meanings, def is usually a descendant of an element carrying the epub:type property sense-group or phrase-group.

Example 16: an English monolingual dictionary where the meaning of the headword  is described in a definition (epub:type="def").

Example 17: an English-German bilingual dictionary where synonyms are used as short sense descriptions (epub:type="def") to disambiguate  the headword so that the user may find out the correct translation.

2.2.7.7 Translations

A tran represents the translation of a particular meaning of a source language headword, idiom, or example into a target language.

When an entry contains multiple senses or phrases, tran is usually a descendant of an element carrying the epub:type property sense-group or phrase-group.

Example 18: an English-German bilingual dictionary which shows that translations (epub:type="tran") may occur on different levels of an entry.

2.2.7.8 Translation-Related Information

A tran-info represents grammatical or usage information related to a translation. It must have a sibling element carrying the tran epub:type property.

Example 19: an English-German bilingual dictionary which demonstrates grammatical  (gender) and usage information (“fam” stands for the register “familiar”) on the translation using epub:type="tran-info".

2.2.8 Phrases

2.2.8.1 Introduction

This section is informative

Phrases represent a fundamental type of information contained in dictionary entries. There are two basic types of phrases distinguished in this specification: the idiom, which is a phrase whose meaning is defined in an entry, and the example, which is a phrase that illustrates the meaning and usage of a headword or idiom. Since idioms represent defined phrases, Authors may choose to treat them as search keys, allowing users to find them via lookup (see Example 28 under Search Key Map Documents for details).

Phrases typically are associated with other semantic elements of a descriptive nature (such as definitions and translations) or an organizational one (such as a sense list). As with parts of speech and senses, all of the information related to a phrase can be grouped together and a series of such groups can be organized as a list.

2.2.8.2 Idioms

An idiom represents a defining instance of a phrase. This property must be used on the dfn element, and carries the same restrictions on nearest ancestors and use of the title attribute as dfn generally.

If the headword itself is an idiom (for instance, in a dictionary of idioms), then idiom may be a child of dictentry. Otherwise, an idiom must be a child of a phrase-group containing related definitions, translations, and examples.

2.2.8.3 Examples

An example represents a sentence demonstrating the usage of a headword or idiom.

When an entry contains multiple senses or phrases, an example should be marked up as part of the sense-group or phrase-group for which it demonstrates usage.

2.2.8.4 Phrase Lists

A phrase-list represents a list of phrase-groups in a dictionary entry.

Use of phrase-list is restricted to the ol or ul element. Each li child of a phrase-list ol or ul has an implied phrase-group epub:type property.

Example 20: a phrase-list in an English-German bilingual dictionary. Note that the list contains both an idiom and an example .

2.2.8.5 Phrase Groups

A phrase-group represents a unit for organizing information pertaining to an idiom or example. It must contain at least one example element or idiom dfn element as a descendant.

The recommended markup for a sequence of phrase groups is a phrase-list ol. It is preferred for accessibility reasons, and also avoids repetition by implying the phrase-group epub:type property on all its li descendants.

2.2.9  Synonyms and Antonyms

2.2.9.1 Synonym Groups

A synonym-group represents a group of terms, each having identical or similar meaning to the headword.

If a synonym-group occurs in a phrase-group, it contains synonyms or near synonyms of any preceding idiom dfn in the phrase-group. Otherwise, it contains synonyms of all preceding dfn elements in the article.

Refer to antonym-group below for an example.

2.2.9.2 Antonym Groups

An antonym-group represents a group of terms, each having an opposite or nearly opposite meaning from a headword or idiom.

If an antonym-group occurs in a phrase-group, it contains antonyms or near antonyms of any preceding idiom dfn in the phrase-group. Otherwise, it contains antonyms or near antonyms of all preceding dfn elements in the article.

Example 21: synonym-group and antonym-group in a thesaurus entry.

2.3 Content Documents - Glossaries

2.3.1 The Glossary Container

A dl, body, section or other sectioning content element carrying an epub:type glossary property represents a collection of glossary terms and definitions in an EPUB Glossary. As shown in example 22 below, if the epub:type glossary property is carried by a dl element, the glossterm and glossdef epub:type properties are implied on its dt and dd children (respectively), allowing for less verbose markup.

An EPUB Glossary consists of all elements carrying an epub:type glossary property in a given Rendition of the Publication and at least one Search Key Map Document that links search keys to the Content Document locations where terms are defined. A Search Key Map Document provides a central resource for Reading System glossary search, thereby providing Authors the choice of organizing glossary content into (a) cohesive, alphabetized section(s) of a Publication or distributing glossary terms and definitions throughout the Publication.

The mechanism for identifying an EPUB Glossary in the package document is described in Glossary Identification.

2.3.2 Glossary Terms and Definitions

A glossterm represents a glossary term, and a glossdef represents the definition of a term in a glossary.

Authors are encouraged to use dfn in glossary markup to identify the exact term being defined, typically within a dt element.

When the glossary epub:type property is carried by a dl element, the logical association of glossary terms and definitions follows the name-value groups described in [HTML5]. In other words, a group of adjacent dd elements are definitions for the terms represented by nearest preceding group of adjacent dt siblings.

Example 22: an alphabetically ordered dl with the glossary property. The glossterm property is implied on the dt elements, while the glossdef property is implied on the dd elements. Note the use of dfn to indicate the exact terms defined in the dt elements.

Example 23: glossary terms/definitions that are distributed throughout a Publication . As in the previous example, the glossary  dl causes the glossterm property to be implied on the dfn elements and the glossdef property  to be implied on the dd elements.

Example 24: glossary terms/definitions that are distributed throughout an index. Note that such a combined index/glossary needs to conform to both EPUB Indexes [Indexes] and glossary markup standards.

2.3.3 Phonetic Transcriptions in Glossaries

The phonetic-transcription epub:type property is permitted in glossaries, See Phonetic Transcriptions under Content Documents - Dictionaries for detailed usage information.

2.4 Search Key Map Documents

2.4.1 Introduction

This section is informative

Search Key Map Documents contain information intended to assist Reading Systems in implementing powerful search functionality. A Search Key Map Document maps search keys to corresponding entries (or part thereof) in an EPUB Dictionary or EPUB Glossary. No distinction is made as to the linguistic nature of the mapped search keys; they can contain not only direct terms or headwords but also inflected forms, idioms, and alternate script forms (e.g. Chinese pinyin). The Search Key Map Document also allows the definition of a default result form that may be rendered by the Reading System in a list of matches. The result form may differ from the search key, and is meant to enable the display of disambiguation aids (for example, Japanese yomi) to the user.

No conformance criteria are defined on how a Reading System is supposed to leverage a Search Key Map Document. The search functionality can be directly based on the XML machine-readable data, but Reading Systems would more commonly construct a more efficient binary search index from it.

Each EPUB Dictionary features exactly one Search Key Map Document and each EPUB Glossary features at least one Search Key Map Document, as specified in the section Search Key Map Identification.

2.4.2 Content Conformance

A Search Key Map Document must meet all of the following criteria:

Document Properties

• It must meet the conformance constraints on XML documents defined in XML Conformance.
• It must be valid to the Search Key Map Document schema, as defined in Appendix A.2, Search Key Map Document Schema, and conform to all content conformance constraints expressed in Search Key Map Document Definition.

File Properties

• The Search Key Map Document filename should use the file extension .xml.

Search Key Map Documents have the MIME media type application/vnd.epub.search-key-map+xml. This specification adds this media type to the list of EPUB 3 Core Media types [EPUB-Publications], meaning that Search Key Map Documents can be included in EPUB Publications without the provision of fallbacks.

2.4.3 Reading System Conformance

A Reading System that supports EPUB Dictionaries and Glossaries must meet the following criteria:

• When performing a lookup, if the user-provided word or phrase matches a search key contained in the Search Key Map, then the Reading System must render the matching content.
• The Reading System must process the Search Key Map Document in conformance with all Reading System conformance constraints expressed in Search Key Map Document Definition.

2.4.4 Search Key Map Document Definition

All elements [XML] defined in this section are in the http://www.idpf.org/2007/ops namespace [XMLNS] unless otherwise specified.

2.4.4.1 The search-key-map element

The search-key-map element is the root container of the Search Key Map Document.  

The root element of the Search Key Map Document must have an xml:lang attribute identifying the language used for the search and result forms within the Search Key Map Document..

All of the contents of an EPUB Dictionary or EPUB Glossary should be covered by its constituent Search Key Map Document.

2.4.4.2 The search-key-group element

A search-key-group element in the search-key-map encapsulates all the indexing information related to a single entry in the related EPUB Dictionary or term in the related EPUB Glossary.

If the Search Key Map Document is part of an EPUB Dictionary, the IRI provided in the href attribute must identify the element – carrying an implied or explicit dictentry epub:type property – that represents the related entry in the Content Document.

If the Search Key Map Document is part of an EPUB Glossary, the IRI provided in the href attribute must identify the element – carrying an implied or explicit glossterm epub:type property – that represents the related glossary term in the Content Document.

The IRI value of the href attribute must be relative. Reading Systems must use the IRI of the Search Key Map Document as the base IRI when resolving it to an absolute IRI.

2.4.4.3 The match element

The match element represents the mapping from one or more search keys to a single EPUB Dictionary entry (or part thereof) or to an EPUB Glossary term.

The match element groups computer-readable search keys that should produce matches upon a lookup.

The value attribute – both on the match element or on its value children – represents a single search key. At least one search key must be associated with a match element. When only one search key is defined, it should be represented using a value attribute on the match element rather than using a single value child.

When the match element has a search key defined in its value attribute, this search key also represents the canonical form (i.e. lemma) of the headword indexed by the match element. If present, all of the value children may be considered specific forms (e.g. inflected forms) of that canonical form.  This information can be used by Reading Systems to improve storage or performance (e.g. by leveraging lemmatization rules).

The title attribute represents the default result form of the headword, i.e. the form that may be rendered to the user in a result list. The title attribute may be omitted if the match element has a value attribute, in which case the content of the value attribute also represents the default result form. Otherwise, if the match element has no value attribute, the title attribute is required.

The phonogram attribute may be used to specify the pronunciation of a word in Chinese, Japanese, or other ideographic writing systems. The phonogram attribute provides a reading of a value attribute and would typically contain Japanese yomi or Chinese Pinyin. It does not define a new search key for the match element.

A match element may represent search keys for only a local part of a dictionary entry (for example a specific sense, an idiom, or a derived word). In this case, the matching content may be identified by an IRI provided in the href attribute. The IRI must be relative. Reading Systems must use the IRI of the Search Key Map Document as the base IRI when resolving it to an absolute IRI. When no href attribute is present, the match element represents search keys matching the entire dictionary entry or glossary term referenced by its search-key-group parent.

2.4.4.4 Examples

Example 25: A simple search key map for the headword "get"

Note how the title attribute is used to specify a default result form different from the search key, and how value child elements are used to declare search keys for the inflected forms of the verb.

Example 26: A search key map for a Japanese dictionary

In this example, the match elements do not specify a value attribute, i.e. no search key is considered the canonical form of its related headword. Note also the presence of the phonogram attribute to specify the hiragana reading(s) of the search keys.

Example 27: A search key map for a dictionary in simplified Chinese

In this example, the value attribute of each match element specifies a Chinese word. The Pinyin spelling of that word is defined in both the phonogram attribute and as a search key in a value child element. An alternate Pinyin search key using tone numbers is also supplied in a value child element.

Example 28: A search key map for the headword "colour"

In this example, different match elements are used to specify search keys with the respective American and British spellings of the words. Note also the use of separate match elements to index parts of the dictionary entry like expressions and idioms.

Example 29: Search key map for a fully inflected French verb

The inflected forms are declared as value child elements of the match element for the verb headword. Note that a Reading System may choose to only store the canonical form "regarder" in a compiled binary search index, and use a built-in lemmatization algorithm to map a search key to its canonical form.

Example 30: Search key map showing that a search key can be mapped to several headwords

In this example, the search key "regardant" returns a match for both the headword "regarder" (verb) and "regardant" (adjective). Note how the title attribute is used to disambiguate the result form of the adjective.

2.5 Identification of the Dictionary or Glossary in the Package Document

A dictionary or glossary must be identified in the package document:

• An EPUB Dictionary Publication may consist of a single EPUB Dictionary or multiple EPUB Dictionaries.  An EPUB Dictionary Publication is identified with package-level metadata in each Rendition, and if it consists of multiple EPUB Dictionaries, each is identified in a collection element.
• An EPUB Glossary is always a component of a larger publication and is identified solely in the Manifest section.

2.5.1 Dictionary Identification

2.5.1.1 Identification with dc:type

An EPUB Dictionary Publication must be identified as such in the package metadata of each of its Renditions by including a dc:type element with the value dictionary.

2.5.1.2 Publication consisting of a single EPUB Dictionary

If an EPUB Dictionary Publication consists of a single EPUB Dictionary, it must contain exactly one Search Key Map Document for this Dictionary.

Exactly one Manifest item must be declared as this Search Key Map Document using the search-key-map and dictionary properties, as defined in Manifest item Properties.

Further identification of individual Content Documents is not necessary.

2.5.1.3 Publication consisting of multiple EPUB Dictionaries

When a given Rendition of an EPUB Dictionary Publication consists of multiple EPUB Dictionaries, as is typically the case in bilingual and multilingual dictionaries, the set of files constituting each EPUB Dictionary must be identified using the collection element of the package document with the role attribute set to dictionary.

The dictionary role restricts the collection element as follows:

• it must not contain child collection elements (i.e. it must not define sub-collections).
• it must contain exactly one link child element with an href attribute pointing to a Search Key Map Document
• other link child elements must reference Content Documents or fragments thereof
• it may contain a metadata child element declaring metadata as defined in Additional Dictionary Metadata.

Every EPUB Dictionary must contain a dedicated Search Key Map Document; in other words, two different collection elements with the role dictionary must not contain link elements referencing the same Search Key Map Document.

Search Key Map Documents must be identified in the Manifest using the search-key-map and dictionary properties as defined in Manifest item Properties.

2.5.1.4 Additional Dictionary metadata

EPUB Dictionary metadata must be defined in the following manner:

• Metadata about the EPUB Dictionary Publication must be defined in each Rendition in the package metadata element [Publications301].
• If a given Rendition of the Publication consists of a single EPUB Dictionary, metadata about this EPUB Dictionary must be defined in the package metadata element [Publications301].
• If a given Rendition of the Publication consists of multiple EPUB Dictionaries, metadata about each EPUB Dictionary must be defined in the metadata child element of the collection element representing that EPUB Dictionary. Metadata applying to all the EPUB Dictionaries in the Rendition should be defined and shared in the package metadata element [Publications301].

Unless otherwise specified,  properties defined in the following sections for use in metadata are extending the default EPUB Package Metadata Vocabulary. They are referenceable using the base IRI http://idpf.org/epub/vocab/package/#.

2.5.1.4.1 Identifying the Dictionary type

The dictionary-type property may be used to refine the precise type of an EPUB Dictionary. The dictionary-type property accepts the values listed in the following table.  If none of these terms are explicitly specified, Reading Systems should treat "monolingual" as the assumed value.

Example 31.

 2.5.1.4.2 Identifying the Audience

The audience property from  DCMI Metadata Terms [DCTERMS] may be used to indicate the target audience of the EPUB Dictionary Publication. When its value is drawn from a code list or other formal enumeration, the scheme attribute should be attached to identify its source.

Example 32.

This specification does not require or endorse the use of any specific scheme for the [DCTERMS] audience property.

2.5.1.4.3 Identifying Source and Target Languages

In addition to the publication’s language(s) –as declared in [DCMES] language elements as per section 3.4.5 of EPUB Publications [Publications30]–  the source and target languages for each EPUB Dictionary must be defined in metadata using the source-language and target-language properties with values conforming to  [RFC5646].

In each of its Renditions,  a monolingual EPUB Dictionary Publication contains a single EPUB Dictionary with headwords and other entry content in the same language; hence, its source and target language values are considered identical. In contrast, an EPUB Dictionary in a bilingual EPUB Dictionary Publication always has distinct source and target language values, whether the EPUB Dictionary Publication is unidirectional (e.g. Latin-to-English) or bidirectional (e.g. both English-to-French and French-to-English).

Each EPUB Dictionary in the Publication must have exactly one source language and one or more target languages. Typically, a monolingual or bilingual EPUB Dictionary will have only one target language, whereas each EPUB Dictionary in a multilingual EPUB Dictionary Publication will have two or more target languages.

Please refer to the examples of monolingual, unidirectional bilingual, bidirectional bilingual, and multilingual dictionary metadata.

2.5.2 Glossary Identification

A Publication containing an EPUB Glossary must contain one or more Content Documents in which glossary content resides. Such Content Documents must be identified by adding the value glossary to the properties attribute in their manifest entries.

Example 33.

A Publication containing an EPUB Glossary must contain at least one Search Key Map Document linking to terms defined in the glossaries. When the EPUB Glossary contains glossary terms in multiple languages, a dedicated Search Key Map Document may be used for each of these languages. All glossary terms for a common language should be covered by a single Search Key Map Document.

A Search Key Map Document for an EPUB Glossary must be identified in the Manifest using both the search-key-map and glossary properties as defined in Manifest item Properties.

2.5.3 Manifest item Properties

The following tables define properties for use in the manifest item element’s properties attribute.

The Applies to field indicates which Publication Resource type(s) the given property may be specified on, the Cardinality field indicates the number of times the property must appear within the Package Document scope, and the Usage field indicates usage conditions.

2.5.4 Package Document Examples

2.5.4.1 Glossary Example

The following example shows a textbook Publication containing an EPUB Glossary.

Example 34.

2.5.4.2 Monolingual Dictionary Example

The following example represents a Spanish monolingual EPUB Dictionary Publication. Note that no subtype is specified, which means the value monolingual should be assumed. As the Publication consists of only one EPUB Dictionary, the source- and target-language metadata are added as package-level metadata.

Example 35.

2.5.4.3 Unidirectional Bilingual Dictionary Example

The following example represents an English-to-Spanish bilingual EPUB Dictionary Publication; it is unidirectional and does not contain Spanish-to-English translations. The subtype is set to the value bilingual. As the Publication consists of only one EPUB Dictionary, the source- and target-language metadata are added as package-level metadata.

Example 36.

2.5.4.4 Bidirectional Bilingual Dictionary Example

The following example represents a bilingual EPUB Dictionary Publication containing distinct English-to-German and German-to-English EPUB Dictionaries.  Each EPUB Dictionary is identified by a collection element, with its own source-language and target-language properties, and including its own Search Key Map Document. In addition, there is an EPUB Glossary with its own Search Key Map Document. In an EPUB Dictionary Publication, a glossary might define abbreviations whose use is specific to the dictionary (as opposed to abbreviations in general use in a language).

Example 37.

2.5.4.5 Multilingual Dictionary Example

The following example shows metadata and manifest elements for a multilingual English-French-Arabic EPUB Dictionary Publication consisting of three distinct EPUB Dictionaries (one for each translation direction). Each dictionary is contained in a single file ordered according to its source language (the language of the words being looked up) with translation information provided in the two target languages.

Example 38.

3. Conformance Criteria

3.1 Content Conformance

An EPUB Publication [EPUB30] that complies with this specification must contain one or more EPUB Dictionaries and/or EPUB Glossaries. A Publication containing one or more EPUB Dictionaries is referred to as an EPUB Dictionary Publication.

An EPUB Dictionary Publication must meet all of the following criteria:

• Each Rendition’s Package Document [EPUB30] must contain metadata that complies with Identification of the Dictionary or Glossary in the Package Document.
• Each EPUB Dictionary must contain at least one content document with at least one element whose epub:type attribute has the value dictionary and whose content complies with Content Documents - Dictionaries.
• Each Search Key Map Document must comply with Search Key Map Documents.

An EPUB Publication containing an EPUB Glossary must meet all of the following criteria:

• Each Rendition’s Package Document [EPUB30] must contain metadata that complies with Identification of the Dictionary or Glossary in the Package Document.
• It must contain at least one content document with at least one element whose epub:type attribute has the value glossary and whose content complies with Content Documents - Glossaries.
• Each Search Key Map Document must comply with Search Key Map Documents.

3.2 Reading System Conformance

A Reading System that complies with this specification must meet all of the following criteria:

• It must identify any EPUB Dictionaries or EPUB Glossaries contained in the Publication using the metadata defined in Identification of the Dictionary or Glossary in the Package Document.
• It must process Search Key Map Documents in compliance with 2.4.3 Reading System Conformance.
• It must provide a user reading an EPUB Publication a means to perform a lookup of a user-provided word or phrase in EPUB Dictionaries available to the Reading System.
• It must provide a user consulting an EPUB Dictionary Publication a means to perform a lookup of a user-provided word or phrase in that Publication’s EPUB Dictionaries.
• It must provide a user reading an EPUB Publication that contains an EPUB Glossary a means to perform a lookup of a user-provided word or phrase in that EPUB Glossary.
• It must comply with the constraints defined in Rendering in Viewports.

A Reading System that complies with this specification should meet all of the following criteria:

• It should select the EPUB Dictionaries used to perform a lookup based on the language context of the EPUB Publication being accessed and the language metadata of EPUB Dictionaries available to the Reading System.
• It should support rendering of Condensed Entries as defined in Condensed and Detailed Entries.

Appendix A. Schemas for Dictionaries in EPUB

A.1 Schema for Dictionary Content Documents

The schema for EPUB Dictionary Content Documents is available at http://www.idpf.org/epub/TODO.

This schema is normative.

A.2 Schema for Search Key Map Documents

The schema for Search Key Map Documents is available at http://www.idpf.org/epub/TODO.

This schema is normative.

Appendix B. Examples

B.1 English Monolingual Dictionary Example

This section illustrates the structure of an EPUB Dictionary Publication containing a monolingual English EPUB Dictionary.  

Examples 39 and 40 below show abbreviated examples of a Content Document and Search Key Map Document. More extensive Content Document and Search Key Map Document examples are also available. Example 41 consists of a complete Package Document (note: the nav document referenced in the OPF is omitted from this example set).  

Though idioms are treated as search keys in the sample Search Key Map Document, note that this is at the Author’s discretion and not required by the specification.

Example 39: monolingual_dictionary.xhtml

Example 40: monolingual_dictionary_searchkeymap.xml

Example 41: monolingual_dictionary.opf

B.2 French-English Bilingual Dictionary Example

This section illustrates parts of a bidirectional, bilingual French-English EPUB Dictionary Publication.

Example 42 consists of a complete Package Document (note: the nav document referenced in the OPF is omitted from this example set).  An extensive Content Document example is also available, consisting of entries from the French-to-English EPUB Dictionary of that publication.

Example 42: bilingual_dictionary.opf

B.3 Glossary Example

The Terminology section of this specification is available as an example of an EPUB Glossary. The example consists of a glossary content document, Search Key Map Document, and relevant package document structures.

Appendix C. Contributors and Acknowledgments

This appendix is informative

EPUB has been developed by the International Digital Publishing Forum in a cooperative effort, bringing together publishers, vendors, software developers, and experts in the relevant standards.

The EPUB 3 Dictionaries and Glossaries Specification 1.0 was prepared by the International Digital Publishing Forum's Dictionaries Working Group, operating under a charter approved by the membership in January, 2012 under the leadership of:

• Alexander, Jeffrey (Intangible Press) Co-Chair
• Deltour, Romain (DAISY Consortium) Co-Chair (from August 2013)
• Hughes, Daniel (Liguori Publications) Co-Chair (until August 2012)
• Gylling, Markus (IDPF) Advisor

Active members of the working group included:

IDPF Members

• Broome, Karen (Sony Electronics)
• Brown, Alex (Harper Collins)
• Combs, Michele (American Society of Indexing)
• Idan, Ori (Helicon Books)
• Kasdorf, Bill (Apex CoVantage)
• Kerscher, George (DAISY Consortium)
• Kida, Yasuo (Apple Inc.)
• Ko, Ben (VersaPub)
• McKean, Erin (Wordnik)
• Murata, Makoto (Jepa)
• Ream, David (Leverage Technologies)
• Schindler, Wolfgang (PONS)
• Seca, Emmanuelle (Editis)
• Stroup, David (Pearson)
• Tamura, Yasuhisa (Sophia University)
• Siegman, Tzviya (Wiley)

Invited Experts/Observers 

• Bolick, Robert
• Garrish, Matt

References

Normative References

[ContentDocs30] EPUB Content Documents 3.0 .

[EPUB-Core-Media] EPUB 3 Core Media Types.

[EPUBCFI] EPUB Canonical Fragment Identifier (epubcfi) Specification .

[HTML5] HTML5: A vocabulary and associated APIs for HTML and XHTML

[Publications30] EPUB Publications 3.0 .

[RFC2119] Key words for use in RFCs to Indicate Requirement Levels (RFC 2119) . March 1997.

[RFC5646] Tags for Identifying Languages (RFC 5646) . A. Phillips, M. Davis. September 2009.

[SSMLAttributes] SSML Attributes in EPUB Content Documents 3.0.

[StructureVocab] EPUB 3 Structural Semantics Vocabulary 

Informative References

[Indexes] EPUB Indexes 1.0