Recommended Specification 26 August 2015
Please refer to the errata for this document, which may include some normative corrections.
A history of changes to this document is available for review.
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This section is informative
This specification, EPUB Multiple-Rendition Publications, defines the creation and rendering of EPUB® Publications consisting of more than one Rendition.
The need to include more than one Rendition of the content in an EPUB Publication has grown as Reading Systems have evolved and become more sophisticated. While some measure of content adaptation has always been possible at the style sheet level, it is both limited in what it can accomplish and limited to content rendering. Existing fallback mechanisms within the EPUB Package Document similarly only ensure that resources can be rendered.
Adaptation is not just about optimizing styling and positioning content for screen considerations, such as dimensions and color or Reading System orientation, but often involves changing the content itself. The resources and markup required to render a fixed-layout Rendition of an EPUB Publication may overlap with a reflowable version of the same, but the two are never exactly the same. Adaptation also involves adapting the prose of a work. In an increasingly interconnected world, including multiple translations of a work rather than bundling them all separately as single-language EPUB Publications is often a necessity. And adaptation is also about the ability to move from the same spot in one Rendition to the equivalent spot in another as changes in the reading environment occur.
This specification does not define methods for modifying content on the fly, but defines how a Reading System selects from multiple Author-provided Renditions of the content to best match the current device characteristics and User preferences. As changes occur to device orientation or the User's preferred reading modality, for example, the Reading System will be able to check for a better Rendition and seamlessly present it to the User using the functionality defined herein.
The specification addresses each of the major requirements in the discovery of, selection of, and mapping between, multiple Renditions of an EPUB Publication. In particular:
META-INF/metadata.xml file;rootfile elements in the Container Document;Taken together, these features enable the creation of advanced Multiple-Rendition Publications that Reading Systems can adapt to changing User needs.
The method for including multiple Renditions within an OCF Container [OCF301] defined in this specification is not a requirement for the production of compliant EPUB Publications. Multiple Renditions may be included in a Container without adhering to this specification, as the ability to create multiple-Rendition Containers pre-dates this specification.
It is strongly recommended that all future needs for multiple Renditions in a Container follow this specification. Existing implementations that utilize other methods for selecting from multiple Renditions are also encouraged to consider migrating to use this specification to improve the overall interoperability of Multiple-Rendition Publications.
Some of the Rendition selection attributes defined in this specification share common names with Package Document elements and properties [Publications301] as they are designed to reflect that information for selection purposes.
Despite this commonality, this specification does not enforce equivalence between the Rendition selection properties expressed on a rootfile element [OCF301] and the metadata expressed in the corresponding Package Document, as direct equivalence is not always possible.
For example, a multilingual EPUB Publication will define more than one DCMES language element [Publications301] ‒ one for each language ‒ but for Rendition selection only the primary language is defined. Likewise, the language defined in the Package Document could include a specific region code, but for selection purposes the Author might identify only the language code.
The reason for common metadata in both locations is to simplify the selection process: including attributes avoids the requirement to parse each referenced Package Document and allows for expressions of primacy that aren't possible at the package level. It also avoids collisions and ambiguities between metadata being used for different purposes (selection versus rendering).
The selection properties defined in the container.xml file [OCF301] have no rendering behaviors attached to them, either. For example, indicating that a Rendition is fixed layout in the rendition:layout attribute does not trigger fixed layout rendering behaviors within the specified Rendition.
A Reading System renders a Rendition according to the metadata expressed in the Package Document only.
Refer to the EPUB Specifications for definitions of EPUB-specific terminology used in this document.
The container.xml file located in the child META-INF directory of the OCF Container Root Directory [OCF301]. Each Rendition in the Container is identified by a rootfile element [OCF301].
An EPUB Publication that consists of two or more Renditions of the content.
A specialization of the XHTML Content Document, containing machine-readable mappings between equivalent content in different Renditions, conforming to the constraints expressed in Rendition Mapping.
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.
metadata.xml FileTo ensure consistency of metadata at the Publication and Rendition levels, this specification defines the content model of the root metadata element in the metadata.xml file [OCF301] to be the same as the Package Document metadata element [Publications301], with the following differences in syntax and semantics:
meta element [Publications301] is not allowed.meta and link elements are defined in the same namespace as the metadata root element: http://www.idpf.org/2013/metadatametadata.xml file, all attributes allowed on the package element [Publications301] are allowed on the root metadata element.This specification does not define a model for the inheritance of metadata from the Publication level to the Rendition level, as EPUB processing only requires that the default Rendition be recognized by Reading Systems (i.e., reliance on inheritance could result in Reading Systems not locating necessary metadata).
Authors are strongly encouraged to include a complete set of Publication metadata in the default Rendition to ensure cross-compatibility, even when making use of this file.
Titles, languages and other metadata is often not applicable from one Rendition to another, further complicating the sharing of metadata. No assumption can be made that metadata in the metadata.xml file is applicable to any given Rendition, whether the metadata is expressed in the Rendition or not.
As [OCF301] does not define a content model for the metadata.xml file, EPUB Publications that do not conform to this specification can include different metadata. EPUB Publications that are not valid to the schema in Appendix A.1 are not valid Multiple-Rendition Publications as defined by this specification, but might still be valid EPUB 3.0.1 Publications.
Authors are strongly encouraged to migrate to the content model defined in this specification, even if not producing Multiple-Rendition Publications, to ensure consistent processing.
This specification inherits the mechanisms for associating vocabularies defined in 4.2 Vocabulary Association Mechanisms [Publications301] as they relate to the Package Document metadata, with only the following modification: the prefix attribute may be attached only to the root metadata element.
Reserved prefixes [Publications301] for metadata attribute expressions are adopted without change.
This section is informative
For reliable processing of EPUB Publications, each needs to be uniquely identifiable. But uniqueness between EPUB Publications is not enough for total reliability, as more than one version of a given EPUB Publication could exist. As a result, it is also necessary to be able to identify and order each release of an EPUB Publication
To distinguish both these characteristics, the concept of a Release Identifier [Publications301] was introduced in EPUB 3. This identifier is a combination of the Unique Identifier and the last modified date, where the Unique Identifier enables differentiation between EPUB Publications and the last modified date enables differentiation between different versions of the same EPUB Publication.
The problem with this identifier, however, is that it is unique to each Rendition because it is expressed in the Package Document metadata. For example, the last modification dates for Renditions could be different if minor corrections only were necessary to some of them, and each could have a different Unique Identifier. As a result, it only effectively identifies an EPUB Publication if that EPUB Publication contains only one Rendition.
Consequently, a new Release Identifier that covers all the Renditions of the EPUB Publication is necessary for Multiple-Rendition Publications, otherwise comparisons are complicated by trying to figure out which Rendition(s) have changed and how to compare them from one release to the next (e.g., if their order in the container.xml file [OCF301] changes). This section details how to define such a global Release Identifier.
The Release Identifier [Publications301] for a Multiple-Rendition Publication is expressed in the metadata.xml file [OCF301] in the same manner as it is in the Package Document:
dc:identifier element [DCMES] must contain the unique identifier [Publications301] for the EPUB Publication.meta element [Publications301] must contain the last modified date, expressed using the dcterms:modified property [DCTERMS].The identifier must conform to the requirements for identifiers defined in 3.4.3 The DCMES identifier Element [Publications301].
The value of the dcterms:modified property must conform to the pattern and rules defined in 4.1.2 Release Identifier [Publications301]. Only one dcterms:modified property without a refines attribute [Publications301] is allowed in the metadata.xml file.
The following example shows a Release Identifier expressed in the metadata.xml file:
<metadata xmlns="http://www.idpf.org/2013/metadata" xmlns:dc="http://purl.org/dc/elements/1.1/" unique-identifier="pub-id"> <dc:identifier id="pub-id">urn:uuid:A1B0D67E-2E81-4DF5-9E67-A64CBE366809</dc:identifier> <meta property="dcterms:modified">2011-01-01T12:00:00Z</meta> </metadata>
This section is informative
Although each EPUB Publication represents a single work, it is possible to optimize the rendering of that work in any number of different ways. An issue of a magazine, for example, could include a fixed layout version (print replica) for rendering on tablet-sized screens with a reflowable version for smaller cellphone screens where the fixed layout would be scaled to illegibility (or automatically reflowed in unwanted ways if fixed layouts are not supported).
The OCF Container allows multiple Renditions of the content to be included in an EPUB Publication, but does not specify how Reading Systems are to determine the unique properties of the Renditions listed in the Container Document, or select between them.
This section redresses this problem by defining both a set of rendition selection attributes that can be attached to rootfile elements [OCF301] in the Container Document and a processing model that allows Authors to specify which Rendition is the best representation depending on various conditions. Reading Systems can then select the appropriate representation from the list of Renditions to match the current configuration and User preferences.
A Container Document must meet all of the following criteria:
container.xml file specified in Container – META-INF/container.xml [OCF301].rootfile element
[OCF301] for the Default Rendition, but it should include at least one selection attribute ‒ in addition to the optional label ‒ on each subsequent rootfile element.An EPUB Reading System must meet all of the following criteria for Rendition selection:
rendition:media attributeThe rendition:media attribute identifies the media features of a Reading System the given Rendition is best suitable for rendering on.
media
http://www.idpf.org/2013/rendition
may be specified on Container Document rootfile elements [OCF301].
A CSS 3 media query [MediaQueries], where the media type, if specified, must only be the value "all".
As per [MediaQueries], the media query in this attribute must evaluate to true in order for the given Rendition to be selected for rendering. Media queries that evaluate to “not all” per 3.1 Error Handling [MediaQueries] should be treated as false for the purposes of Rendition selection (i.e., the given Rendition is not a valid match).
The following example shows two Renditions of The Sandman bundled in the same container, one optimized for screens 1920 pixels or wider. The Default Rendition will be used for screen sizes smaller than 1920 pixels by default.
<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container"
xmlns:rendition="http://www.idpf.org/2013/rendition"
version="1.0">
<rootfiles>
<rootfile full-path="Sandman.opf"
media-type="application/oebps-package+xml"/>
<rootfile full-path="Sandman-large.opf"
media-type="application/oebps-package+xml"
rendition:media="(min-width: 1920px)"/>
</rootfiles>
</container>
rendition:layout attributeThe rendition:layout attribute indicates whether the given Rendition is reflowable or pre-paginated.
layout
http://www.idpf.org/2013/rendition
may be specified on Container Document rootfile elements [OCF301].
The value of the attribute must be reflowable or pre-paginated.
When specified, the value of this attribute must match the global rendition:layout setting [Publications301] for the referenced Rendition.
If a User layout preference is defined in the Reading System, the attribute evaluates to true if the preference matches the specified value, otherwise it evaluates to false. If no User preference is defined, the Reading System should ignore the attribute when selecting from the available Renditions.
The following example shows two Renditions of a magazine bundled in the same container. Note that it is not necessary to state that the Default Rendition is reflowable, since Renditions are reflowable by default.
<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container"
xmlns:rendition="http://www.idpf.org/2013/rendition"
version="1.0">
<rootfiles>
<rootfile full-path="EPUB/reflow/magazine.opf"
media-type="application/oebps-package+xml"/>
<rootfile full-path="EPUB/fxl/magazine.opf"
media-type="application/oebps-package+xml"
rendition:layout="pre-paginated"/>
</rootfiles>
</container>
rendition:language attributeThe rendition:language attribute indicates that the given Rendition is optimized for the specified language.
The rendition:language attribute more precisely identifies the primary language of a Rendition than does the inclusion of dc:language elements in the Rendition’s Package Document, as the presence of dc:language elements only indicates that the specified languages are prominently used in the prose.
If a User language preference is defined in the Reading System, the attribute evaluates to true if the preference matches the specified value, otherwise it evaluates to false. Several matching schemes are defined in Section 3 of [RFC4647]. Reading systems can use the most appropriate matching scheme. If no User preference is defined, the Reading System should ignore the attribute when selecting from the available Renditions.
The following example shows a multilingual EPUB Publication, with English, French and Spanish Renditions of the content.
<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container"
xmlns:rendition="http://www.idpf.org/2013/rendition"
version="1.0">
<rootfiles>
<rootfile full-path="EPUB/en/package.opf"
media-type="application/oebps-package+xml"
rendition:language="en"/>
<rootfile full-path="EPUB/fr/package.opf"
media-type="application/oebps-package+xml"
rendition:language="fr"/>
<rootfile full-path="EPUB/es/package.opf"
media-type="application/oebps-package+xml"
rendition:language="es"/>
</rootfiles>
</container>
rendition:accessMode attributeThe rendition:accessMode attribute identifies the way in which intellectual content is communicated in a Rendition, and is based on the [ISO24751-3] "Access Mode" property.
accessMode
http://www.idpf.org/2013/rendition
may be specified on Container Document rootfile elements [OCF301].
must be one or more of the values: auditory, tactile, textual or visual
The rendition:accessMode attribute defines the primary access mode(s) for a given Rendition. For example, although a textual work may include images, audio and video, its primary means of conveying information is the text. Likewise, a visual work might include alternative text and/or descriptions, but these adaptations are not listed as a textual mode for the Rendition for the purpose of selection.
The way in which information is encoded also needs to be considered when designating an access mode. If a work has text components, or is completely textual in nature, but that content is burned into an image format, the access mode is visual (e.g., character dialogue in a JPEG page of a comic or a scan of a document).
A rendition may include more than one primary access mode. For example, the textual version might also embed the auditory version using media overlays. In such cases, the attribute should list each primary access mode that is available.
If a User access mode preference is defined in the Reading System, the attribute evaluates to true if that preference matches any of the access modes defined in it, otherwise it evaluates to false. If no User preference is defined, the Reading System should ignore the attribute when selecting from the available Renditions.
The rendition:label attribute can be use to inform Users about the nature of the content, particularly where such information is not available, or not yet standardized, for selection. For example, a tactile rendition could indicate the braille code and grade in its label, or a textual rendition could be marked as optimized for text-to-speech rendering, not general use.
The following example shows an EPUB Publication with an image-based Rendition and a text-based serialization available.
<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container"
xmlns:rendition="http://www.idpf.org/2013/rendition"
version="1.0">
<rootfiles>
<rootfile full-path="EPUB/comic/package.opf"
media-type="application/oebps-package+xml"
rendition:accessMode="visual"/>
<rootfile full-path="EPUB/novel/package.opf"
media-type="application/oebps-package+xml"
rendition:accessMode="textual"/>
</rootfiles>
</container>
rendition:label attributeThe rendition:label attribute allows each rootfile element [OCF301] to be annotated with a human-readable name.
label
http://www.idpf.org/2013/rendition
may be specified on Container Document rootfile elements [OCF301].
Text.
The rendition:label attribute provides a name for the given rendition (e.g., for manual rendition selection).
The language of the rendition:label attribute may be expressed in an xml:lang attribute.
The following example shows the rendition:label attribute being used to provide a human-readable name for a Rendition.
<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container"
xmlns:rendition="http://www.idpf.org/2013/rendition"
version="1.0"
xml:lang="en">
<rootfiles>
…
<rootfile full-path="EPUB/package.opf"
media-type="application/oebps-package+xml"
rendition:media="color, min-width: 1024"
rendition:layout="pre-paginated"
rendition:label="Color-optimized print replica"/>
</rootfiles>
</container>
The rendition:label attribute is not a selection attribute for the purposes of evaluating which Rendition to render.
This section describes the method by which Reading Systems locate the optimal Rendition to present to a User.
Rendition selection should occur on initial rendering, and Reading Systems should re-evaluate the selection in response to changes in the User environment (e.g., change in device orientation or viewport size).
When a change condition is triggered, the Reading System should evaluate the rootfile elements [OCF301] in the Container Document as follows, starting with the last rootfile entry:
rootfile element and continue the evaluation process.rootfile element and continue the evaluation process.If the Default Rendition is reached, select that Rendition and exit the process.
This processing model does not require that the selection process occur on a User's device, or that all Renditions be provided in the Container. Rendition selection could occur on the server side of a cloud-based delivery system, for example, and only a single best-match Rendition sent to the device.
Since EPUB 2 Reading Systems, and EPUB 3 Reading Systems that do not support multiple-Rendition selection, will render the Default Rendition, Authors need to consider which Rendition will have the greatest compatibility across Reading Systems and ensure it is listed first.
A Reading System may provide the User the option to manually select any of the Renditions in the Container. It should use the rendition:label attribute attribute value to present the option, when available.
As EPUB did not previously define a Rendition selection model, custom selection models might be encountered in some EPUB Publications. When recognized, these selection models should be utilized. If both rendition selection attributes conformant to this specification and custom attributes are defined, the latter should be ignored.
This section is informative
The Rendition Mapping Document identifies related content locations across the Renditions in a Multiple-Rendition Publication, allowing Reading Systems to switch between Renditions while keeping the User’s place.
The Rendition Mapping Document is represented as XHTML, and uses nav elements with unordered lists to group the mappings. There is no display component to the Rendition Mapping Document; it is designed to enable automated switching. The lack of a rendering context means that the XHTML content model for this document is very restrictive, allowing only a single nav element in the body, to ease both authoring and processing.
To enable the mapping of content locations between Renditions, the Rendition Mapping Document’s nav element consists of a series of one or more unordered lists, each of which represents a common point across all the Renditions (e.g., a chapter, a page or a component within a page). The list items in each unordered list represent the set of equivalent link destinations across the available Renditions for that content (e.g., one link might point to a document representing one page of a fixed layout Rendition, while the equivalent link to a reflowable Rendition might point to the corresponding page break indicator within the XHTML Content Document containing the page).
Knowing the position of the User in the current Rendition, when a change in context occurs, or is triggered by the User, the Reading System can inspect the sibling list items to determine the EPUB Content Document to load that best meets the new conditions.
An EPUB Publication may include an EPUB Rendition Mapping Document.
A conformant EPUB Rendition Mapping Document must meet all of the following criteria:
Document Properties
Publication
Reading Systems should support the use of Rendition Mapping Documents to switch between content.
If a Reading System supports mapping, it must meet all of the following criteria:
The Rendition Mapping Document is a compliant EPUB XHTML Content Document, but with the following restrictions on the [HTML5] content model:
html, head, body, ul and li elements. (The xmlns pseudo-attribute for namespace declarations is allowed.) The nav element only accepts an epub:type attribute.head may contain only meta elements. Only the charset attribute or name and content attributes may be attached to the meta elements.head must include a meta element whose name attribute has the value "epub.multiple.renditions.version" and whose content attribute has the value "1.0". Reading Systems may ignore all other meta elements.body element must include exactly one nav element child whose epub:type attribute specifies the value "resource-map", and may include one or more optional nav elements. No other [HTML5] content is allowed as a child of the body.This specification restricts the content model of nav elements and their descendants in the Rendition Mapping Document as follows:
nav element must identify its nature in an epub:type attribute.ul) in place of ordered lists (ol).nav element may contain one or more ul element.li) must contain exactly one a element (i.e., span headings and nested lists are forbidden).a elements must be empty.a element must specify the rendition it is referring to either:href attribute or,epub:rendition attribute whose value is the relative path to the Publication Document for the rendition.Each ul element in the Rendition Mapping Document resource-map nav element identifies a content location, listing in its child li elements where that location is found in each of the available Renditions. Consequently, each ul element must contain an li for each Rendition.
In order to allow a broad variety of use cases, this specification does not impose any particular level of mapping granularity. For example, some publications aimed at language learners may define sentence-level synchronisation points, whereas other types of publications may only map major sections across Renditions.
Each list item in the unordered list must identify an EPUB Content Document, or a fragment therein, for one of the Renditions ‒ defined in a child a element. Each of these links must reference a linear Top-level Content Document [Publications301].
Each a element must specify which Rendition it refers to either 1) by including an Intra-Publication CFI [EPUBCFI] in its href attribute, or 2) by providing the relative path to the Package Document for the Rendition as the value of an epub:rendition attribute.
If the epub:rendition attribute is used to specify the target Rendition, any fragment identifier scheme may be used within the URI value of the href attribute of a elements (e.g., unique identifier, or W3C Media Fragment).
The use of [EPUBCFI] expressions is strongly encouraged over other fragment identifier schemes (particularly in the context of reflowable XHTML Content Documents), as they allow Reading Systems to ingest Rendition Mappings without any prior pre-processing. Conversely, the use of unique identifiers forces Reading Systems to load the targeted Content Documents and process their DOM in order to sort/compare the link destinations (in relation to document order). This additional processing has performance implications, and implementation costs in terms of caching, incremental updating, etc.
Examples
The following example shows a Rendition Mapping Document for a magazine with 3 Renditions: text, portrait and landscape. ‘article 1’ is on pages 5 and 6 of the fixed layout Renditions and the landscape Rendition uses spreads (non-synthetic).
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8"/> </head> <body> <nav epub:type="resource-map"> <ul> <!-- First Page of the Article 1 --> <li> <a href= "../../text/default.opf#epubcfi(/6/8[article1]!/4/2:20)" /> </li> <li> <a href="../../images/page5.png" epub:rendition="../../portrait/portrait.opf" /> </li> </ul> <ul> <!-- Second Page of the Article 1 --> <li> <a href= "../../text/default.opf#epubcfi(/6/8[article1]!/4/22:40)" /> </li> <li> <a href="../../images/page6.png" epub:rendition="../../portrait/portrait.opf" /> </li> </ul> <ul> <!-- Article 1 --> <li> <a href= "../../text/default.opf#epubcfi(/6/8[article1])" /> </li> <li> <a href="../../images/page5-6.png" epub:rendition="../../landscape/landscape.opf" /> </li> </ul> </nav> </body> </html>
The following example shows a multilingual EPUB Publication with each language in a separate Rendition.
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8"/> </head> <body> <nav epub:type="resource-map"> <ul> <!-- Chapter 1 --> <li><a href = "../../en/en.opf#epubcfi(/6/2)" /></li> <li><a href = "../../fr/fr.opf#epubcfi(/6/4)" /></li> <li><a href = "../../de/de.opf#epubcfi(/6/2)" /></li> <li><a href = "../../es/es.opf#epubcfi(/6/6)" /></li> <li><a href = "../../it/it.opf#epubcfi(/6/2)" /></li> </ul> <ul> <!-- Chapter 2 --> <li><a href = "../../en/en.opf#epubcfi(/6/4)" /></li> <li><a href = "../../fr/fr.opf#epubcfi(/6/6)" /></li> <li><a href = "../../de/de.opf#epubcfi(/6/4)" /></li> <li><a href = "../../es/es.opf#epubcfi(/6/8)" /></li> <li><a href = "../../it/it.opf#epubcfi(/6/6)" /></li> </ul> <ul> <!-- Chapter 3 --> <li><a href = "../../en/en.opf#epubcfi(/6/6)" /></li> <li><a href = "../../fr/fr.opf#epubcfi(/6/8)" /></li> <li><a href = "../../de/de.opf#epubcfi(/6/6)" /></li> <li><a href = "../../es/es.opf#epubcfi(/6/10)" /></li> <li><a href = "../../it/it.opf#epubcfi(/6/8)" /></li> </ul> <!-- … could be even more fine grained for better results … --> </nav> </body> </html>
The location of the Rendition Mapping Document is identified in the Container Document using an [OCF301] link element child of the root container element, where:
href attribute must reference the location of the Rendition Mapping Document relative to the root of the OCF Container;rel attribute must specify the value “mapping";media-type attribute must specify the value “application/xhtml+xml".The Container Document must not reference more than one mapping document.
The following example shows the container.xml file for a multilingual EPUB Publication. The location of the Rendition Mapping Document is included in the link element.
<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container"
xmlns:rendition="http://www.idpf.org/2013/rendition"
version="1.0">
<rootfiles>
<rootfile full-path="en/en.opf"
rendition:language="en"
media-type="application/oebps-package+xml" />
<rootfile full-path="de/de.opf"
rendition:language="de"
media-type="application/oebps-package+xml" />
</rootfiles>
<links>
<link href="renditionMapping.html"
rel="mapping"
media-type="application/xhtml+xml" />
</links>
</container>
This section is informative
This section provides an informative model by which the Rendition Mapping Document could be processed by a Reading System. It does not address how or when a Reading System should switch Renditions.
The desired outcome of the Rendition Mapping Document’s mapping capabilities is to display content in the new Rendition that is equivalent to their location in the current Rendition, so that a user maintains their place during reading. To accomplish this goal, a compliant Reading System could follow these steps to reset the current Rendition when a change condition is triggered:
ul elements to find ones that contain li elements with child a elements that both specify the same rendition and intersect the current range:ul element, the Reading System would navigate to the beginning of the range in the new rendition. ul element, then the Reading System behavior is undefined. The Reading System might prompt the User to select between the new locations, or might choose between them using its own heuristics.ul elements are found, the Reading System will have to determine the location to navigate to in the new Rendition as if there was no Rendition Mapping Document.Note that what happens during navigation is largely a user experience issue, so a Reading System might choose to consider additional information than above to try to achieve a better outcome.
Validation using the schemas in this appendix requires a processor that supports [RelaxNG] and [XSD-DATATYPES].
This section is informative
The schema for including metadata in the metadata.xml file, as described in 2. Publication Metadata, is available at http://www.idpf.org/epub/renditions/multiple/schema/mr-metadata.rnc.
This section is informative
The schema for including rendition selection attributes in the container.xml file, as described in 3. Rendition Selection, is available at http://www.idpf.org/epub/renditions/multiple/schema/mr-container.rnc.
The schema for Mapping Documents, as described in 4. Rendition Mapping, is available at http://www.idpf.org/epub/renditions/multiple/schema/epub-rendition-mapping.rnc.
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 Multiple-Rendition Publications 1.0 specification was prepared by the International Digital Publishing Forum's Advanced/Hybrid Layouts working group, operating under a charter approved by the membership in November 2012, under the leadership of:
Active members of the working group included:
IDPF Members
Invited Experts/Observers