Copyright © 2022-2023 the Contributors to the Page Source Identification Specification, published by the Publishing Community Group under the W3C Community Final Specification Agreement (FSA). A human-readable summary is available.
This proposal defines the pageBreakSource property to identify the source of page markers
and the page list in EPUB publications.
This specification was published by the Publishing Community Group. It is not a W3C Standard nor is it on the W3C Standards Track. Please note that under the W3C Community Final Specification Agreement (FSA) other conditions apply. Learn more about W3C Community and Business Groups.
GitHub Issues are preferred for discussion of this specification.
Providing navigation to static page break markers is a key accessibility feature for digital publications that are used in both print and digital formats in the same environment (e.g., classrooms). But without a means of identifying what edition of a static work the page navigation corresponds to, it is impossible for users to determine if the publication will be sufficient for their needs. For example, if a class uses a softcover edition of a book and the EPUB publication pagination corresponds to the hardcover, digital users will not be able to access the same page break locations.
How to identify the source of pagination has been a continuing problem in the EPUB 3 metadata. The
original idea was to use a dc:source element [epub-3] to specify the pagination. This method proved
unreliable both for machine verification that the EPUB creator had set the method and to extract and
present the information to users. Publishers sometimes specify multiple sources for their
publications in multiple dc:source elements, making it impossible for a machine to
determine which identifies the source.
To address this problem, the specification then introduced a "refinement" [epub-3] property called source-of [epub-3] whose
only purpose was to indicate which dc:source property identified the source.
Since its addition, however, two additional problems have surfaced with this approach:
refines attribute was nearly dropped in EPUB 3.1, it exposed that there was
still no other way to express this information. Consequently, future formats cannot rely on the
source-of property.dc:source confuses how to state that a digital-only publication does not
have a source for its markers. EPUB creators have resorted to identifying the current
publication as the source of itself or saying that the publication has a source of nothing for
the pagination, neither of which makes much sense logically and are at best hacks of the
metadata. Omitting a dc:source, while accurate in this situation, makes validation
difficult as it cannot be determined whether the EPUB creator simply forgot to specify the
source.The pageBreakSource property proposed in this document is intended to provide a simple
and reliable solution to these problems moving forward.
This specification uses terminology defined in EPUB 3 [epub-3].
Only the first instance of a term in a section links to its definition.
As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.
The key word MUST in this document is to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
| Name: |
pageBreakSource
|
|---|---|
| Description: |
Provides a unique identifier for the source of the page break markers in an EPUB publication. The identifier should be expressed as a URN when the value conforms to a recognized scheme such as an ISBN. If a unique identifier does not exist for the source, EPUB creators should use a text description that identifies the source as clearly as possible (e.g., the title of a word processing document). If the page break markers are unique to the EPUB publication (e.g., for a digital-only
edition), EPUB creators MUST specify the value " |
| Allowed value(s): |
xsd:string
|
| Cardinality: | Exactly one when the publication includes a page list and/or page break markers, otherwise 0. |