IDPF Adoption Readiness Roadmap for Multiple Renditions
2. Epubcheck support
3. Support in EPUB Conformance Test Suite (epubtest.org)
4. Authoring tool support
5. Reading system support
a. Readium (JS & SDK)
b. other open source
c. commercial reading systems
6. Primer/best practice documentation
7. Backwards compatibility assessment
a. Legacy EPUB 2 RS
b. EPUB 3.0 RS
c. EPUB 3.01 RS
8. Fallback feasibility assessment
9a. Polyfillability assessment
9b. Browser compatibility assessment
10. Accessibility implications assessment
Support for validating metadata, selection attributes and mapping documents has been added to the latest epubcheck 4.0 alpha release.
A test for the ability to access the multiple renditions in a container has been added to a development branch for edupub compliance. This test will be included on the site in a future update. Including as a separate test for any EPUB 3 publication will also be considered for a future update.
Future updates might also include tests for the following:
DAISY Pipeline support for creating Braille rendition
Prototype build of Readium with support for Multiple Renditions
No separate primer/best practice documents are planned at this time.
A publication that conforms to the multiple renditions specification will be readable in an EPUB 2 reading system with the same limitations of any EPUB 3.0.1 publication. Only the default rendition will be available in most cases, since support for multiple renditions was typically not available. Metadata in the metadata.xml file will similarly be ignored as the file was not standardized, and the mapping documents won't be recognized as they rely on a linking mechanism not available in EPUB 2.
A publication that conforms to the multiple renditions specification will be readable in exactly the same manner as any EPUB 3.0.1 publication. Similar to EPUB 2 reading systems, only the default rendition will be available in most cases.
No difference in rendering between EPUB 3.0 and EPUB 3.0.1 compliant reading systems is expected. The linking mechanism used for mapping documents was introduced in 3.0.1, but unknown links are ignored. Similarly, the metadata.xml file was given a standard root element for metadata, but multiple renditions follows the new usage requirements, so even if the reading system is not aware of this specification nothing should break.
Multiple renditions take advantage of the built-in fallback mechanisms in the OCF Container, namely that the default rendition will always be rendered if the inclusion of more than one rootfile element is not recognized. Access to the additional renditions cannot be addressed if the reading system itself does not provide access.
No changes are required to the underlying browser cores as the functionality introduced is not at the content level. Support needs to occur at a higher level in processing of the container, as demonstrated by the Readium-based implementation (see 5a).
This specification has the potential to greatly improve the accessibility of EPUB 3 publications as it allows alternate-format renditions to be discovered both automatically, based on preset user preferences, and manually by user selection.
For example, a braille rendition can be identified at the container.xml level, allowing automatic presentation. Similarly, an accessible reflowable rendition could be bundled with a fixed-layout rendition, and a full-ruby rendition with one without ruby annotations.