This specification, the Open Packaging Format (OPF), is one third of a triumvirate of modular specifications that make up the EPUB publication format. EPUB enables the creation and transport of reflowable digital books and other types of content as single-file digital publications that are interoperable between disparate EPUB-compliant reading devices and applications. EPUB encompasses a content markup standard (Open Publication Structure – OPS), a container standard (Open Container Format – OCF), and this specification, a packaging standard.
In order for electronic-book technology to achieve widespread success in the
marketplace, Reading Systems need to have convenient access to a large number and
variety of titles. Another related specification, the Open
Publication Structure (OPS) Specification, describes a standard for
representing the content of electronic publications and is meant to reduce barriers to
the proliferation of content. Specifically, the specification is intended to:
- Give publication tool providers and content providers (e.g. publishers, authors,
and others who have content to be displayed) minimal and common guidelines that ensure
fidelity, accuracy, accessibility, and adequate presentation of electronic content over
various Reading Systems; and
- Build on established content format standards; and
- Define a standard means of content description in order for electronic books to
move smoothly through the distribution chain.
This document, the Open Packaging Format (OPF) Specification, defines the mechanism by
which the various components of an OPS publication are tied together and provides
additional structure and semantics to the electronic publication. Specifically, OPF:
- Describes and references all components of the electronic publication (e.g. markup
files, images, navigation structures).
- Provides publication-level metadata.
- Specifies the linear reading-order of the publication.
- Provides fallback information to use when unsupported extensions to OPS are
employed.
- Provides a mechanism to specify a declarative
table of contentsglobal navigation structure (the NCX).
This OPF specification is separate from the OPS markup specification to modularize the
described packaging methodology and the described content. This will help facilitate
the use of this packaging technology by other standards bodies (e.g.
DAISY) in non-OPS contexts.
A third specification, the OEBPSOpen Container Format (OCF) Specification, defines the
standard mechanism by which all components of an electronic publication can be packaged
together into a single file for transmission, delivery and archival.
Together, these three standards constitute EPUB.
Content Provider
A publisher, author, or other information provider who provides a publication to one
or more Reading Systems in the form described in this specification and the OPS
specification.
Deprecated
A feature that is permitted, but not recommended, by this
specification. Such features might be removed in future revisions. Conformant Reading
Systems must support deprecated features.
EPUB
The publication format as defined by the OCF 2.0.1, OPF 2.0.1, and OPF 2.0.1 specifications.
EPUB Publication
A collection of OPS Documents, an OPF Package file, and other files, typically in a variety of media types, including structured text and graphics, packaged in an OCF container that constitute a cohesive unit for publication, as defined by the EPUB standards.
EPUB Reading System (or Reading System)
A combination of hardware and/or software that accepts EPUB Publications and makes them available to consumers of the content. Great variety is possible in the architecture of Reading Systems. A Reading System may be implemented entirely on one device, or it may be split among several computers. In particular, a reading device that is a component of a Reading System need not directly accept OCF-Packaged EPUB Publications, but all Reading Systems must do so. Reading Systems may include additional processing functions, such as compression, indexing, encryption, rights management, and distribution.
Extended Module
A module of a modularized XML vocabulary (i.e. a set of named modules is defined in
its specification) that is not mandated to be supported by its specification (e.g.
the XHTML ruby or forms modules in the OPS context).
Inline XML Island
An inline XML Island is an XML document fragment using a non-Preferred Vocabulary or
using an Extended Module that exists within an XHTML Preferred Vocabulary document
within an OPS Publication.
NCX
A declarative table of contentsglobal navigation definition (the Navigation Center eXtended or NCX).
OCF
The OEBPSOpen Container Format defines a mechanism by which all components of an OPS
Publication can be combined into a single file-system entity. OCF is defined by the OCF Specification.
OEBPS
The Open Publication Structure. Previous versions of this specification
(OPF) and its related specification, OPS, were unified into the single OEBPS
specification. For this version, OEBPS was broken into separate OPF and OPS
specifications to aid modular adoption of the specifications. OEBPS 1.2 was the
highest version of the previous unified specification.
OPF
The Open Packaging Format — this standard — defines the mechanism by which all
components of a published work conforming to the OPS standard including metadata,
reading order and navigational information are packaged into an OPS Publication.
OPF Package Document
An XML Document that describes an OPS Publication and references all files used by
the OPS Publication that are not part of the OPF Package Document itself. It
identifies all other files in the Publication and provides descriptive information
about them. The OPF Package Document is defined by this specification and is valid to
the OPF Package Schema defined herein.
The "root file" of the OPF Package Document should use the
.opf extension. This XML file may
refer to other XML files via XML’s general entity mechanism, but those files
must not use the .opf file
extension. This construction could be used to simplify the creation of OPF Package
Documents for very large Publications. However, the most common case is for the OPF
Package Document to be a single XML file using the .opf
extension.
OPS
The Open Publication Structure — the sister-standard to this standard — defines the
markup necessary to construct OPS Content Documents. OPS is defined by the OPS Specification.
OPS Content Document
An XHTML, DTBook, or out-of-line XML document that conforms to the OPS specification
that can legally appear in the OPF Package Document spine.
OPS Core Media Type
A MIME media type, defined in the OPS Specification, that all Reading Systems
must support.
OPS Publication
A collection of OPS Content Documents, an OPF Package Document, and other files,
typically in a variety of media types, including structured text and graphics, that
constitute a cohesive unit for publication.
Out-of-Line XML Island
An Out-Of-Line XML Island is an XML document that exists within an OPS Publication
and is either not authored using a Preferred Vocabulary or is authored using a
Preferred Vocabulary but uses Extended Modules. It is an entirely separate, complete,
and valid XML document.
Preferred Vocabulary
XML consisting only of OPS-supported XHTML markup and/or DTBook markup.
Reader
A person who reads a publication.
Reading System
A combination of hardware and/or software that accepts OPS Publications (likely
packaged in an OCF Container) and makes them available to consumers of the content.
Great variety is possible in the architecture of Reading Systems. A Reading System
may be implemented entirely on one device, or it
may be split among several computers. In particular, a
Reading Device that is a component of a Reading System need
not directly accept OPS Publications, but all Reading Systems must do so. Reading Systems may include
additional processing functions, such as compression, indexing, encryption, rights
management, and distribution.
See EPUB Reading System.
XML Document
An XML Document is a complete and valid XML document as defined in XML 1.1 (http://www.w3.org/TR/xml11/).
An XML Document is a complete and valid XML document as defined in XML 1.0 (Fourth Edition) (http://www.w3.org/TR/2006/REC-xml-20060816/).
XML Document Fragment
Referred to as either a document fragment or as an XML Document Fragment, as defined
in Document Object Model Level 1 (http://www.w3.org/TR/REC-DOM-Level-1/) but
with the additional requirement that they be well-formed.
XML Island
An Inline XML Island or an Out-of-Line XML island.
XML Namespaces
Referred to as XML namespaces, or just namespaces, these must conform to XML
Namespaces (http://www.w3.org/TR/xml-names11/).
(http://www.w3.org/TR/2006/REC-xml-names-20060816/).
This specification combines subsets and applications of other specifications. Together,
these facilitate the construction, organization, presentation, and unambiguous
interchange of electronic documents:
-
Extensible Markup Language (XML) 1.
10 (SecondFourth Edition)
specification (http://www.w3.org/TR/xml11/); and
(http://www.w3.org/TR/2006/REC-xml-20060816/); and
-
Namespaces in XML 1.0 (Second Edition)
(http://www.w3.org/TR/xml-names11/);
(http://www.w3.org/TR/2006/REC-xml-20060816/);
and
- The OPS Specification (http://www.idpf.org/
ops/ops2.0/download/doc_library/epub/OPS_2.0.1_draft.htm);
and
-
XHTML™ 1.1 - Module-based XHTML - Second Edition
specification (http://www.w3.org/TR/xhtml11/); and
-
Specifications for the Digital Talking Book (DTB)
(http://www.niso.org/standards/resources/Z39-86-2005.html);
and
-
Dublin Core Metadata Element Set, Version 1.1
specification (http://dublincore.org/documents/2004/12/20/dces/)
and the MARC relator code list (http://www.loc.gov/marc/relators/); and
-
Unicode Standard, Version 4.0. Reading, Mass.:
Addison-Wesley, 2003, as updated from time to time by the publication of new
versions. (See http://www.unicode.org/unicode/standard/versions for
the latest version and additional information on versions of the standard and of
the Unicode Character Database); and
- Particular MIME media types (http://www.ietf.org/rfc/rfc4288.txt
and http://www.iana.org/assignments/media-types/index.html);
and
-
Web Content Accessibility Guidelines 1.0 (http://www.w3.org/TR/WCAG10/); and
-
RFC 2119: Key words for use in RFCs to Indicate Requirement
Levels. (http://www.ietf.org/rfc/rfc2119.txt).
OPF is based on XML because of XML’s generality and
simplicity, and because XML documents are likely to adapt well to future technologies
and uses. XML also provides well-defined rules for the syntax of documents, which
decreases the cost to implementers and reduces incompatibility across systems.
Further, XML is extensible: it is not tied to any particular type of document or set
of element types, it supports internationalization, and it encourages document markup
that can represent a document’s internal parts more directly, making them amenable to
automated formatting and other types of computer processing.
- Reading Systems must be XML processors as defined in XML
1.
10. All OPF Package Documents must be valid XML documents
according to the OPF Package Schema.
Reading Systems may support XML 1.1, but this feature is deprecated in version 2.0.1 (in favor of XML 1.0). Support for XML 1.1 will be removed in the next version of the specification.
Reading Systems must process XML namespaces according to the
XML Namespaces Recommendation at http://www.w3.org/TR/xml-names11/http://www.w3.org/TR/2006/REC-xml-names-20060816/.
Namespace prefixes distinguish identical names that are drawn from different XML
vocabularies. An XML namespace declaration in an XML document associates a namespace
prefix with a unique URI. The prefix can then be employed on element or attribute
names in the document. Alternatively, a namespace declaration in an XML document
may identify a URI as the default namespace, applicable to
elements lacking a namespace prefix. The XML namespace prefix is separated from the
suffix element or attribute name by a colon.
The namespace for the OPF Package Document is http://www.idpf.org/2007/opf, and must be
declared at the root of all OPF Package Documents. In addition, to be processed as an
OPF 2.0 package, a version attribute with a value of
2.0 must be specified on
the package
element. A package element that omits the
version attribute must be
processed as an OEBPS 1.2 package.
Example:
<package version="2.0" xmlns="http://www.idpf.org/2007/opf">
...
</package>
Dublin Core metadata is designed to minimize the cataloging
burden on authors and publishers, while providing enough metadata to be useful. This
specification supports the set of Dublin Core 1.1 metadata elements (http://dublincore.org/documents/2004/12/20/dces/),
supplemented with a small set of additional attributes addressing areas where more
specific information is useful. For example, the OPF
role attribute added to the Dublin Core
creator and contributor elements allows for much more detailed
specification of contributors to a publication, including their roles expressed
via relator codes.
Content providers must include a minimum set of metadata
elements, defined in Section 2.2, and should
incorporate additional metadata to enable readers to discover publications of
interest.
OPF Package Documents may use the entire Unicode character
set, in UTF-8 or UTF-16 encodings, as defined by Unicode (see http://www.unicode.org/unicode/standard/versions). The
use of Unicode facilitates internationalization and multilingual documents.
However, Reading Systems are not required to provide
glyphs for all Unicode characters.
Reading Systems must parse all UTF-8 and UTF-16 characters
properly (as required by XML). Reading Systems may decline
to display some characters, but must be capable of signaling
in some fashion that undisplayable characters are present. Reading Systems
must not display Unicode characters merely as if they were
8-bit characters. For example, the biohazard symbol (0x2623) need
not be supported by including the correct glyph, but must
not be parsed or displayed as if its component bytes were the two characters
"&#" (0x0026 0x0023).
To aid Reading Systems in implementing consistent searching and sorting behavior it
is required that Unicode Normalization Form C (NFC) be used
(See http://www.w3.org/TR/charmod-norm/).
The keywords "must", "must not",
"required", "shall", "shall not", "should", "recommended", "may", and "optional" in this document must be interpreted as
described in RFC 2119.
This section defines conformance for OPF Package Documents, and Reading Systems that
process those Documents.
This specification defines conformance for both individual OPF Package Documents and
for a collection of files including exactly one OPF Package Document that
collectively are referred to as an OPS Publication.
Each conformant OPF Package Document must meet these
necessary conditions:
- it is a well-formed XML document (as defined in XML 1.
10); and
- it is encoded in UTF-8 or UTF-16; and
- it is a valid XML document according to the OPF Package Schema defined in
Appendix A; and
- it may consist of one or more XML files, but only one
may use the file extension .opf.
A collection of files is a conforming OPS Publication if:
- it includes a single OPF Package Document that obeys the Package Conformance
Requirements listed above; and
-
only one file in the Publication may use the file
extension .opf. If such a file is present, it
must be the "root file" of the OPF Package Document;
and
- the OPF Package Document includes one and only one manifest entry corresponding
to each other file in the OPS Publication excluding the file or files that make up
the OPF Package Document itself; and
- the manifest entry for each file in the publication specifies a MIME media type
for the file (see http://www.ietf.org/rfc/rfc2046.txt);
and
- each file whose manifest entry identifies it as being in one of the OPS Core
Media Types conforms as defined for those MIME media types; and
- each file listed in the spine of the OPF Package Document must conform to the OPS Content Document requirements defined in the
OPS specification; and
-
anthe required NCX, encoded in either UTF-8 or UTF-16, is must be included; and
- the metadata element or deprecated dc-metadata element contains at least one identifier element, at least one title element, and at least one language element drawn from the Dublin Core tag set; and
- the unique-identifier attribute of the
package element is a correct XML IDREF to a Dublin Core identifier
element; and
- any extended values specified for the Dublin Core creator and contributor elements' OPF
role attribute must be
taken from the registered MARC Relator Code list or must
begin with oth.; and
- any extended values specified for the guide
element's type attribute begin with other.; and
- the version attribute of the package element is specified with a value of 2.0; and
- the package element's namespace
mustis be
http://www.idpf.org/2007/opf; and
- any required fallbacks are included per Section 2.3.1.
This specification and the OPS specification impose additional conformance
constraints on the Package Document and on OPS Content Documents.
This specification defines conformance for a Reading System when presented with an
OPS Publication. OPS Content documents have further conformance requirements that can
be found in the OPS specification. A Reading System is conformant if and only if it
processes documents as follows:
- When presented with an OPF Package Document the Reading System
must
- process all elements and attributes as described in Section 2 of this specification; and
- ignore all elements and attributes not described in Section 2 of this specification; and
- verify the existence of the appropriate namespace specifications, as defined
in the Relationship to XML Namespaces
section above.
- When providing navigation via the OPF spine, the Reading System must not render content that is not an OPS Content Document.
- When presented with an OEBPS 1.2 Package, the Reading System must process it as a conformant OEBPS 1.2 Reading System would. Note
that only the OEBPS 1.2 Package must be processed as an
OEBPS 1.2 Reading System would, not the content documents referred to in the Package.
- When presented with an OEBPS 1.2 Publication, a Reading System
should process it as a conformant OEBPS 1.2 Reading System would. Such a
Reading System can claim an optional level of Reading System conformance, "Backward
Compatibility Conformance."
Version 2.0 of OPF is not meant to be a substantially "new" specification. However,
version 2.0 does add one significant functional enhancement in addition to a number
of other changes from OEBPS version 1.2. Specifically, the following are the most
substantive additions:
- XML 1.1 is incorporated.
- XML namespace processing is now required.
- Support for DAISY’s Navigation Center eXtended (NCX)
has been added to enhance ease of navigation and accessibility of publications.
-
Dublin Core element names must now be lower case to conform to Dublin Core’s XML implementation
recommendations.
- The tours element has been deprecated.
While most changes from version OEBPS 1.2 to OPF 2.0 have been done via deprecation
rather than removal of previous functionality, the OEBPS 1.2 Package is not a fully
compatible subset of OPF 2.0 (e.g. new namespace processing requirements).
A publication conforming to this specification must include
exactly one XML OPF Package Document, which specifies the OPS Content Documents, images,
and other objects that make up the OPS Publication and how they relate to each other.
The OPF Package Document should be named
ending in the extension ".opf", in order to make it readily identifiable within the group
of files making up the publication. The OPS Package Document is of MIME media type
application/oebps-package+xml. This specification does not
define means for physically bundling files together to make one data transfer object
(such as using zip or tar); the OEBPSOpen Container Format (OCF) specifies this
functionality.
This specification neither precludes nor requires the inclusion of the OPF Package Schema
in a Publication.
The major parts of the OPF Package Document are:
Package Name
A unique identifier for the OPS Publication as a whole.
Metadata
Publication metadata (title, author, publisher, etc.).
Manifest
A list of files (documents, images, style sheets, etc.) that make up the publication.
The manifest also includes fallback declarations for files of types not supported by
this specification.
Spine
An arrangement of documents providing a linear reading order.
Tours (Deprecated)
A set of alternate reading sequences through the publication, such as selective views
for various reading purposes, reader expertise levels, etc.
Guide
A set of references to fundamental structural features of the publication, such as
table of contents, foreword, bibliography, etc.
An OPF Package Document must be a valid XML document conforming
to the OPF Package schema (Appendix A). An informal outline of the package is
as follows:
<?xml version="1.0"?>
<package version="2.0" xmlns="http://www.idpf.org/2007/opf" unique-identifier="BookId">
metadata
manifest
spine
guide
</package>
The following sections describe the parts of the OPF Package Document.
The package element is the root element in an OPF Package
Document; all other elements are nested within it.
The package element must specify a value for its unique-identifier attribute. The unique-identifier attribute's value specifies which Dublin Core
identifier element, described in Section 2.2.10, provides the
package's preferred, or primary, identifier. The OPF Package Document's author is
responsible for choosing a primary identifier that is unique to one and only one
particular package (i.e., the set of files referenced from the package document's
manifest).
Notwithstanding the requirement for uniqueness, Reading Systems must
not fail catastrophically if they encounter two distinct packages with the same
purportedly unique primary identifier.
The required metadata element is
used to provide information about the publication as a whole. It may contain Dublin Core metadata elements
directly or within a (now deprecated) dc-metadata
sub-element. Supplemental metadata can also be specified directly or within a (now
deprecated) x-metadata sub-element.
Reading Systems must allow the specification of the deprecated
dc-metadata and x-metadata
elements. Newly created OPS 2.0 packages should not create
dc-metadata or x-metadata
elements. If the dc-metadata element is used, all
dc elements must go in
dc-metadata and all other metadata elements, if any, must go into
x-metadata. If the dc-metadata element is not used, all metadata elements must go directly in the metadata element.
The required metadata or
dc-metadata (deprecated) elements contain specific
publication-level metadata as defined by the Dublin Core Metadata Initiative (http://www.dublincore.org/). The descriptions below
are included for convenience, and the Dublin Core's own definitions take precedence
(see http://dublincore.org/documents/2004/12/20/dces/).
One or more optional instances of a meta element, analogous to the XHTML 1.1 meta element but applicable to the publication as a whole,
may be placed within the metadata
element or within the deprecated x-metadata element. This
allows content providers to express arbitrary metadata beyond the data described by the
Dublin Core specification. Individual OPS Content Documents may include the meta element directly (as in
XHTML 1.1) for document-specific metadata. This specification uses the OPF Package
Document alone as the basis for expressing publication-level Dublin Core metadata.
For example:
<metadata xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:opf="http://www.idpf.org/2007/opf">
<dc:title>Tale of Two Cities</dc:title>
<dc:creator opf:role="aut">Charles Dickens</dc:creator>
...
<meta name="price" content="USD 19.99" />
</metadata>
The XML namespace mechanism (see http://www.w3.org/TR/REC-xml-names11/http://www.w3.org/TR/2006/REC-xml-names-20060816/) is
used to identify the elements used for Dublin Core metadata without conflict. The
metadata or dc-metadata
(deprecated) elements may contain any number of instances of any Dublin Core
elements. Dublin Core metadata elements may occur in any order; in fact, multiple
instances of the same element type (e.g. multiple Dublin Core creator elements) can be interspersed with other metadata elements
without change of meaning.
Each Dublin Core field is represented by an element whose content is the field's value.
At least one of each of Dublin Core title, identifier and language must be included in the metadata element.
Dublin Core elements, like any other elements in the OPF Package Document, may have an id attribute specified. At
least one Dublin Core identifier, which is referenced from
the package unique-identifier attribute, must have an id specified.
Because the Dublin Core metadata fields for creator and
contributor do not distinguish roles of specific
contributors (such as author, editor, and illustrator), this specification adds an
optional role attribute for this purpose. See Section 2.2.6 for a discussion of role.
To facilitate machine processing of Dublin Core creator
and contributor fields, this specification adds the
optional file-as attribute for
those elements. This attribute is used to specify a normalized form of the contents.
See Section 2.2.2 for a discussion of file-as.
This specification also adds a scheme attribute to the
Dublin Core identifier element to provide a structural
mechanism to separate an identifier value from the system or authority that generated
or defined that identifier value. See Section 2.2.10 for a discussion of scheme.
This specification also adds an event attribute to the
Dublin Core date element to enable content providers to
distinguish various publication specific dates (for example, creation, publication,
modification). See Section 2.2.7 for a discussion of event. For example:
<package version="2.0" xmlns="http://www.idpf.org/2007/opf"
unique-identifier="BookId">
<metadata xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:opf="http://www.idpf.org/2007/opf">
<dc:title>Alice in Wonderland</dc:title>
<dc:language>en</dc:language>
<dc:identifier id="BookId" opf:scheme="ISBN">
123456789X
</dc:identifier>
<dc:creator opf:role="aut">Lewis Carroll</dc:creator>
</metadata>
...
</package>
There are no attributes for the elements within metadata defined by Dublin Core — only
the elements' contents are so defined. In the above example, the specification of the
OPF namespace on the metadata element is present to
resolve the scheme and role attributes used in the identifier
and creator elements, respectively.
For compatibility with Guidelines for implementing Dublin Core in XML (http://dublincore.org/documents/dc-xml-guidelines/)
this specification allows xsi:type attribute for metadata items that can be given
using some sort of encoding scheme and xml:lang attribute when an item can be given
using human-readable text. Elements that allow xsi:type attribute are identifier,
language, date, format and type. Elements that allow xml:lang attribute are: title,
contributor, coverage, creator, description, publisher, relation, rights, source,
and subject. This specification does not impose any specific rules for these
attributes (with possible exception of heuristics that use xml:lang described
below).
The following subsections describe the individual Dublin Core metadata elements.
The title of the publication. An OPF Package Document must
include at least one instance of this element type, however multiple instances are
permitted. Any Reading System that displays title metadata should display the content of the most appropriate title element(s). Determination of the most appropriate titles is
not defined by this specification, but may include the
available fonts, an examination of xml:lang
attributes, or other heuristics. In the absence of such an algorithm, conforming
Reading Systems should consider either the first
title element or all the title elements as the most appropriate.
A primary creator or author of the publication. Additional contributors whose
contributions are secondary to those listed in creator
elements should be named in contributor elements.
Publications with multiple co-authors should provide
multiple creator elements, each containing one author.
The order of creator elements is presumed to define the
order in which the creators' names should be presented by
the Reading System.
This specification recommends that the content of the creator elements hold the text for a single name as it would be
presented to the Reader.
This specification adds to the creator element two
optional attributes: role and
file-as. The set of values for role are identical to those defined in Section 2.2.6 for the contributor element. The file-as
attribute should be used to specify a normalized form of
the contents, suitable for machine processing. For example, one might find
<dc:creator opf:file-as="King, Martin Luther Jr." opf:role="aut">
Rev. Dr. Martin Luther King Jr.
</dc:creator>
Any Reading System that displays creator metadata should
display the content of the most appropriate creator
element(s). Determination of the most appropriate creators is not defined by this
specification, but may include the available fonts, an
examination of xml:lang attributes, or other
heuristics. In the absence of such an algorithm, conforming Reading Systems
should display the contents of all creator elements, in the order provided, with appropriate separating
spacing and/or punctuation.
Multiple instances of the subject element are supported,
each including an arbitrary phrase or keyword. This specification makes no attempt to
standardize subject naming schemes, such as the Library of Congress Subject Heading
System.
Description of the publication's content.
A party whose contribution to the publication is secondary to those named in
creator elements.
Other than significance of contribution, the semantics of this element are identical
to those of creator. Reading Systems are free to choose
to display creator information without accompanying contributor information.
This specification adds to the contributor element two
optional attributes: role and
file-as. The file-as
attribute is defined as for creator, and is documented
in Section 2.2.2.
The normative list of values used for the role
attribute is defined by the MARC relator code list (http://www.loc.gov/marc/relators/). When roles
are specified, the 3-character registered MARC values must be used when applicable. Although that list is extensive, other
values may be added if a desired role is not covered by those predefined values.
Such values must begin with oth., and shall be
considered subdivisions of the other relator
code. Like other constructs in this specification, these values are case-sensitive
and must be coded entirely in lower-case.
For convenience, some relator code values are listed here as examples. Consult the
MARC code list cited above for the complete list.
|
Adapter [adp]
|
Use for a person who 1) reworks a musical composition, usually for a different
medium, or 2) rewrites novels or stories for motion pictures or other audiovisual
medium.
|
|
Annotator [ann]
|
Use for a person who writes manuscript annotations on a printed item.
|
|
Arranger [arr]
|
Use for a person who transcribes a musical composition, usually for a different
medium from that of the original; in an arrangement the musical substance remains
essentially unchanged.
|
|
Artist [art]
|
Use for a person (e.g., a painter) who conceives, and perhaps also implements, an
original graphic design or work of art, if specific codes (e.g., [egr], [etr])
are not desired. For book illustrators, prefer Illustrator [ill].
|
|
Associated name [asn]
|
Use as a general relator for a name associated with or found in an item or
collection, or which cannot be determined to be that of a Former owner [fmo] or
other designated relator indicative of provenance.
|
|
Author [aut]
|
Use for a person or corporate body chiefly responsible for the intellectual or
artistic content of a work. This term may also be used when more than one person
or body bears such responsibility.
|
|
Author in quotations or text extracts [aqt]
|
Use for a person whose work is largely quoted or extracted in a works to which he
or she did not contribute directly. Such quotations are found particularly in
exhibition catalogs, collections of photographs, etc.
|
|
Author of afterword, colophon, etc. [aft]
|
Use for a person or corporate body responsible for an afterword, postface,
colophon, etc. but who is not the chief author of a work.
|
|
Author of introduction, etc. [aui]
|
Use for a person or corporate body responsible for an introduction, preface,
foreword, or other critical matter, but who is not the chief author.
|
|
Bibliographic antecedent [ant]
|
Use for the author responsible for a work upon which the work represented by the
catalog record is based. This can be appropriate for adaptations, sequels,
continuations, indexes, etc.
|
|
Book producer [bkp]
|
Use for the person or firm responsible for the production of books and other
print media, if specific codes (e.g., [bkd], [egr], [tyd], [prt]) are not
desired.
|
|
Collaborator [clb]
|
Use for a person or corporate body that takes a limited part in the elaboration
of a work of another author or that brings complements (e.g., appendices, notes)
to the work of another author.
|
|
Commentator [cmm]
|
Use for a person who provides interpretation, analysis, or a discussion of the
subject matter on a recording, motion picture, or other audiovisual medium.
Compiler [com] Use for a person who produces a work or publication by selecting
and putting together material from the works of various persons or bodies.
|
|
Designer [dsr]
|
Use for a person or organization responsible for design if specific codes (e.g.,
[bkd], [tyd]) are not desired.
|
|
Editor [edt]
|
Use for a person who prepares for publication a work not primarily his/her own,
such as by elucidating text, adding introductory or other critical matter, or
technically directing an editorial staff.
|
|
Illustrator [ill]
|
Use for the person who conceives, and perhaps also implements, a design or
illustration, usually to accompany a written text.
|
|
Lyricist [lyr]
|
Use for the writer of the text of a song.
|
|
Metadata contact [mdc]
|
Use for the person or organization primarily responsible for compiling and
maintaining the original description of a metadata set (e.g., geospatial metadata
set).
|
|
Musician [mus]
|
Use for the person who performs music or contributes to the musical content of a
work when it is not possible or desirable to identify the function more
precisely.
|
|
Narrator [nrt]
|
Use for the speaker who relates the particulars of an act, occurrence, or course
of events.
|
|
Other [oth]
|
Use for relator codes from other lists which have no equivalent in the MARC list
or for terms which have not been assigned a code.
|
|
Photographer [pht]
|
Use for the person or organization responsible for taking photographs, whether
they are used in their original form or as reproductions.
|
|
Printer [prt]
|
Use for the person or organization who prints texts, whether from type or plates.
|
|
Redactor [red]
|
Use for a person who writes or develops the framework for an item without being
intellectually responsible for its content.
|
|
Reviewer [rev]
|
Use for a person or corporate body responsible for the review of book, motion
picture, performance, etc.
|
|
Sponsor [spn]
|
Use for the person or agency that issued a contract, or under whose auspices a
work has been written, printed, published, etc.
|
|
Thesis advisor [ths]
|
Use for the person under whose supervision a degree candidate develops and
presents a thesis, memoir, or text of a dissertation.
|
|
Transcriber [trc]
|
Use for a person who prepares a handwritten or typewritten copy from original
material, including from dictated or orally recorded material.
|
|
Translator [trl]
|
Use for a person who renders a text from one language into another, or from an
older form of a language into the modern form.
|
Date of publication, in the format defined by "Date and Time Formats" at http://www.w3.org/TR/NOTE-datetime and by
ISO 8601 on which it is based. In particular, dates without times are represented
in the form YYYY[-MM[-DD]]: a required 4-digit year, an
optional 2-digit month, and if the month is given, an
optional 2-digit day of month.
The date element has one optional OPF event attribute. The set of
values for event are not defined by this specification; possible values may include: creation, publication, and modification.
type includes terms describing general categories,
functions, genres, or aggregation levels for content. The advised best practice is to
select a value from a controlled vocabulary.
The media type or dimensions of the resource. Best practice is to use a value from a
controlled vocabulary (e.g. MIME media types).
A string or number used to uniquely identify the resource. An OPF Package Document
must include at least one instance of this element type,
however multiple instances are permitted.
At least one identifier must
have an id specified (the value being of the XML
"ID" data type), so it can be referenced from the package unique-identifier attribute described in Section 2.1.
The identifier element has an optional OPF scheme attribute defined by
this specification. The scheme attribute names the
system or authority that generated or assigned the text contained within the
identifier element, for example "ISBN" or "DOI." The values of the scheme attribute are case sensitive only when the particular
scheme requires it.
This specification does not standardize or endorse any particular publication
identifier scheme. Specific uses of URLs or ISBNs are not yet addressed by this
specification. Identifier schemes are not currently defined by Dublin Core.
Identifies a language of the intellectual content of the Publication. An OPF Package
Document must include at least one instance of this element
type, however multiple instances are permitted. The content of this element
must comply with RFC 3066 (see http://www.ietf.org/rfc/rfc3066.txt), or its successor on
the IETF Standards Track. The Dublin Core permits other descriptions as well; this
specification does not.
An identifier of an auxiliary resource and its relationship to the publication.
A statement about rights, or a reference to one. In this specification, the copyright
notice and any further rights description should appear
directly.
This specification does not address the manner in which a Content Provider specifies
to a secure distributor any licensing terms under which readership rights or copies
of the content could be sold.
The required manifest
must provide a list of all the files that are
part of the publication (e.g. Content Documents, style sheets, image
files, any embedded font files, any included schemas).
All DTDs and external entities (including, but not limited to, external DTD references)
referenced by XML documents listed in the package manifest
are considered part of the publication and thus must also be listed in the
manifest. As an exception to that rule, DTDs of certain core document
types do not need to be included. The list of DTDs that do need to be included in the
manifest is:
-
SVG 1.1 DTD (www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd)
-
XHTML 1.1 DTD (www.w3.org/TR/xhtml11/DTD/xhtml11.dtd)
-
DTBook DTD (www.daisy.org/z3986/2005/dtbook-2005-2.dtd)
-
NCX DTD (www.daisy.org/z3986/2005/ncx-2005-1.dtd)
The manifest element must contain one or more
item elements. Each item
describes a document, an image file, a style sheet, or other component that is
considered part of the publication. The manifest
must not include item elements
referring to the file or files that make up the OPF Package Document.
Each item element contained within a manifest element must have the attributes id, href (a URI; if relative, the URI
is interpreted as relative to the OPF Package Document file containing the reference),
and media-type (specifying the item’s MIME media type).
The order of item elements in the manifest is not
significant.
For example:
<manifest>
<item id="intro" href="introduction.html"
media-type="application/xhtml+xml" />
<item id="c1" href="chapter-1.html"
media-type="application/xhtml+xml" />
<item id="c2" href="chapter-2.html"
media-type="application/xhtml+xml" />
<item id="toc" href="contents.xml"
media-type="application/xhtml+xml" />
<item id="oview" href="arch.png"
media-type="image/png" />
</manifest>
The URIs in href attributes of item elements in the manifest
must not use fragment identifiers.
A single resource (href) must
not be listed in the manifest more than once.
A Content Document’s root element must be consistent with the
media-type of the associated item element within the manifest.
The OPS specification defines a set of OPS Core Media Types that all conforming
Reading Systems must support (e.g. XHTML, PNG, SVG). For a
publication that uses only those media types, the manifest merely lists the publication's component files directly.
However, content providers may construct publications that
reference items of additional media types. In order for such publications to be read
by all conforming Reading Systems, content providers must
provide alternative "fallback" items for each such item. For every item that is not
an OPS Core Media Type, at least one of its associated fallback items must either be of a type drawn from the set of OPS Core Media Types or,
in some cases, CSS styling may be provided for documents
containing non-preferred XML vocabularies.
This specification and the OPS specification jointly define fourfive different mechanisms
for specifying OPS Core Media Type fallbacks. These are as follows:
- For inline "replaced" resources referenced via the object element, this specification relies on that element’s inherent
replacement capabilities, described in Section 2.3.6 of the OPS specification.
- For inline "replaced" resources referenced via the img element, the text value of the alt or title
attributes provide a valid fallback, described in Section 2.3.4 of the OPS specification.
- For Inline XML Islands a switch-based fallback mechanism is provided, described
in Section 2.6.3.1 of the
OPS specification.
- For fonts embedded using the @font-face mechanism, when using such fonts, the basic
rules of CSS are used to provide fallback information. There is no requirement to add
fallback data to manifest item's
for embedded fonts. As an informative example, the following CSS is considered to have
sufficient fallback information
@font-face {
font-family: "My Font";
src: url(fonts/MyFont.otf)
}
p {
font-family: "My Font", serif
}
- For non-inline destinations, whether referenced from a document or a package, and
for inline "replaced" resources referenced via the img
element, the various attributes of the package item
element are used to provide fallback information. This is defined in
this
Section 2.3.1.1 of
this specification.
For the purpose of fallback specification, thea file with the media type application/x-dtbncx+xml that specifies the publication’s NCX (see
below) should be considered a Core Media Type, thus fallback
information must not be provided for this file.
Following from #4, above, for the purpose of fallback specification, a file with the media type application/vnd.ms-opentype that specifies an embedded OpenType font
should be considered a Core Media Type, thus fallback
information must not be provided for this file. The media type application/vnd.ms-opentype should be specified as the
media-type value in the item of the
manifest that references an OpenType font.
For the purpose of fallback specification, schema definition files with media types of supported schema
languages should be considered as Core Media Types, thus fallback
information must not be provided for these files. These schema
languages are:
- DTD, including DTD fragments, (*.net, *.mod): application/xml-dtd
- RelaxNG XML syntax and NVDL: application/xml
- RelaxNG Compact Syntax: application/relax-ng-compact-syntax
An item that specifies a resource that is not an OPS
Core Media Type (e.g. a
non-core image type, a text file, a PDF file) must have
a fallback specified (excepting those with inherent or exempted fallbacks as detailed above
in Section 2.3.1).
In this case, its fallback must be identified with a
fallback attribute pointing to another item. See Section 2.3.1.2 for fallback
requirements for Out-of-Line XML Islands.
An item identifies a fallback item using its fallback attribute,
which must specify the ID
of the item element that identifies the fallback.
Items referenced from fallback attributes
may each specify a fallback
attribute in turn, forming a multi-level fallback chain. For example:
<manifest>
<item id="item1"
href="FunDoc.txt"
media-type="text/plain"
fallback="fall1" />
<item id="fall1" fallback="fall2"
href="FunDoc.pdf"
media-type="application/pdf" />
<item id="fall2"
href="FunDoc.html"
media-type="application/xhtml+xml" />
<item ...>
</manifest>
If a fallback attribute points to an item that also has a fallback
attribute, a Reading System must continue down the
fallback chain until it reaches a reference to an item
with a media type it can display (or as specified below, it reaches an item with a fallback-style
attribute). A Reading System may continue further, and
may display any item from the
chain. In the absence of element-specific (i.e. img
and object) fallback information, every item in a publication that does not have one of the OPS Core Media
Types must, directly or indirectly, specify a fallback to
an item that does have one of the OPS Core Media Types
(or as specified below, an item with a fallback-style attribute).
Fallback chains must terminate; circular references are
not permitted. Nevertheless, Reading Systems should not
fail catastrophically if they encounter such a loop.
An item that specifies a resource that is an
Out-Of-Line XML Island (an XML document that is not authored in a Preferred
Vocabulary). An item is an Out-Of-Line XML Island if:
- It specifies a resource that is an XML document not authored in a Preferred
Vocabulary (i.e. an XML document with a media-type
that is neither application/xhtml+xml, application/x-dtbook+xml nor the deprecated text/x-eob1-document); or
- It specifies a resource that is an XML document authored in a Preferred
Vocabulary and incorporates the use of Extended Modules.
More information is needed, and more freedom is provided, for fallback
determination and processing of Out-Of-Line XML Islands. The namespace of an
Out-Of-Line XML Island item must be specified with the required-namespace attribute and its fallback must be identified with either a fallback attribute pointing to another item or by providing CSS styling that can be used to render the
island via the fallback-style attribute.
If the fallback attribute is specified, Reading
System processing is identical to the Non-OPS Core Media Types handling described
above.
If the fallback-style attribute is specified, a
Reading System may choose to process the Out-Of-Line XML
Island (even though it can not natively process the vocabulary or Extended Modules
used in the island) using the stylesheet specified by the fallback-style attribute's value which must contain a reference to the id of
the item containing an href to the stylesheet desired for the island.
Both fallback and fallback-style attributes may be
specified, in which case the Reading System may choose to
either follow the fallback chain or to process the Out-Of-Line XML Island with the
supplied CSS stylesheet.
An Out-Of-Line XML Island authored in a Preferred Vocabulary by definition
incorporates the use of Extended Modules. In this case, and with non-Preferred
Vocabulary islands utilizing Extended Modules, the required-modules attribute must be
present along with the required-namespace attribute.
The attribute value for required-modules
must be a comma-separated list containing the name(s) of
the Extended Modules used in the Out-of-Line XML Island. The names of the modules
are not case-sensitive, unless specifically defined otherwise in the XML vocabulary
specification. Spaces in module names must be replaced
with "-" for listing in the required-modules
attribute value. For XHTML, in the context of OPS, the Extended Modules include
ruby, forms, server-side-image-map, and intrinsic-events.
Note that listing the names of non-Extended Modules in a required-modules attribute value is also allowed; such modules
are always considered to be supported if the XML vocabulary is supported. This can
be useful both for clarity and in the case where there is a possibility that some
modules could become optional in the later revisions of
the specification (e.g. the currently deprecated Style Attribute XHTML module in
OPS).
It is allowed, and sometimes useful, to provide a required-modules attribute on an item specifying a non-Preferred
Vocabulary Out-Of-Line XML Island — either for clarity or to specify Extended
Modules needed from the non-Preferred Vocabulary.
Most importantly, a Reading System that can natively process the non-Preferred
Vocabulary (or Extended Modules) used for an Out-Of-Line XML Island may choose to use its integral understanding to natively process the
document. However, fallback information must be provided
for Reading Systems that do not have such native processing ability.
For example:
<manifest>
<item id="item1"
href="Doc1.hpy"
media-type="text/happy+xml"
required-namespace="http://happy.com/ns/happy1/"
fallback="item2" />
<item id="item2"
href="Doc1.less-hpy"
media-type="text/less-happy+xml"
required-namespace="http://happy.com/ns/happy2/"
fallback="item2.5"
fallback-style="css1" />
<item id="item2.5"
href="Doc1.htm"
media-type="application/xhtml+xml"
required-namespace="http://www.w3.org/1999/xhtml"
required-modules="ruby, server-side-image-map"
fallback="item3" />
<item id="item3"
href="Doc1.dtb"
media-type="application/x-dtbook+xml" />
<item id="item4"
href="Doc2.hpy"
media-type="text/happy+xml"
required-namespace="http://happy.com/ns/happy1/"
fallback-style="css1" />
<item id="css1"
href="happy.css"
media-type="text/css" />
</manifest>
In the above example when processing item1, a
Reading System could choose to render item1
natively, item2 natively, item2 with only styling from css1, item2.5 natively
(assuming the Ruby and Server Side Image Map XHTML Extended Modules are supported
by the Reading System), or item3 natively. When
processing item4, a Reading System could choose
to render item4 natively or item4 with only styling from css1.
Inclusion of the required-namespace attribute is
not required in item elements
referring to XML documents authored in Preferred Vocabularies unless Extended
Modules are used, in which case both required-namespace and required-modules attributes must be
provided.
Following manifest, there must be one and only one spine element, which
contains one or more itemref elements. Each itemref references an OPS Content Document designated in the
manifest. The order of the itemref elements organizes the associated OPS Content Documents into
the linear reading order of the publication.
Each itemref in spine
must not reference media types other than OPS Content
Documents (or documents whose fallback chain includes an OPS Content Document). An OPS
Content Document must be of one of the following media types:
application/xhtml+xml, application/x-dtbook+xml, the deprecated text/x-oeb1-document, and Out-Of-Line XML Island (with required fallback.) When a document with a
media type not from this list (or a document whose fallback chain doesn't include a
document with a media type from this list) is referenced in spine, Reading Systems must not include it as
part of the spine.
As items appearing in the spine must either be OPS
Content Documents or items with a fallback chain that includes an OPS Content, it is
possible to have a fallback chain for a spine item that
"falls over" another OPS Core Media type. For example, a spine itemref could reference a PDF
document, that falls back to a PNG image, that in turn falls back to a OPS XHTML
Content Document. It is valid for this item to appear in the spine because the fallback chain includes (in this case terminates
with) an OPS Content Document.
In addition, a specific spine item (from the
perspective of its id attribute value in manifest) must not appear more than once in spine.
All OPS Content Documents that are part of the publication (i.e. are listed in the
manifest) which are potentially reachable by any reference mechanism allowed in this
specification must be included in the spine. Such reference mechanisms include, as a partial list, hypertext
links within OPS Content Documents, and references by the NCX, Tours and Guide.
Should a Reading System encounter, by such reference, an OPS Content Document not
listed in spine as required in this specification, the
Reading System should add it to spine (the placement at the discretion of the Reading System) and
assign the value of the linear attribute to no (see next.)
For each itemref, the publication author may specify the optional linear attribute
to designate whether the associated OPS Content Document is primary (linear="yes", which is the default when linear is not present) or auxiliary (linear="no".) It is important that the publication author include
some kind of internal reference, such as a hypertext link, to any OPS Content Document
that is declared to be auxiliary; it is recommended that
references be added to NCX for all auxiliary content. At least one itemref in spine must be declared primary.
Specifying whether an OPS Content Document is primary or auxiliary is useful for
Reading Systems which opt to present auxiliary content differently than primary
content. For example, a Reading System might opt to render auxiliary content in a popup
window apart from the main window which presents the primary content. (For an example
of the types of content that may be considered auxiliary, refer to the example below
and the subsequent discussion.)
Reading Systems are not required to differentiate between
primary and auxiliary content, and for the requirements and recommendations given in
this section may consider all OPS Content Documents in
spine to be primary, regardless of the value of the
linear attribute.
The linear attribute also maintains compatibility
with OEBPS 1.x, where not all reachable OEBPS content documents were required to be
listed in the spine. For upgrading an OEBPS Publication to
OPS, every unlisted, reachable content document in the OEBPS 1.x Publication
should be assigned linear="no".
Reading Systems are to use the ordered itemref
information in spine to present the publication during
reading. Reading Systems must recognize the first primary OPS
Content Document in spine to be the beginning of the main
reading order of the publication. Successive primary OPS Content Documents form the
remainder of the main reading order in the same order given in spine. Reading Systems may use "next-page"
style functionality when moving from one primary OPS Content Document to the next
primary one in spine.
The spine element must
include the toc attribute, whose value is the the
id attribute value of the required NCX document declared in manifest
(see Section 2.4.1.)
Example illustrating spine and the optional
linear attribute:
<manifest>
<item id="intro"
href="intro.html"
media-type="application/xhtml+xml" />
<item id="c1"
href="chap1.html"
media-type="application/xhtml+xml" />
<item id="c1-answerkey"
href="chap1-answerkey.html"
media-type="application/xhtml+xml" />
<item id="c2"
href="chap2.dtb"
media-type="application/x-dtbook+xml" />
<item id="c2-answerkey"
href="chap2-answerkey.html"
media-type="application/xhtml+xml" />
<item id="c3"
href="chap3.html"
media-type="application/xhtml+xml" />
<item id="c3-answerkey"
href="chap3-answerkey.html"
media-type="application/xhtml+xml" />
<item id="note"
href="note.html"
media-type="application/xhtml+xml" />
<item id="f1"
href="fig1.jpg"
media-type="image/jpeg" />
<item id="f2"
href="fig2.jpg"
media-type="image/jpeg" />
<item id="f3"
href="fig3.jpg"
media-type="image/jpeg" />
<item id="ncx"
href="toc.ncx"
media-type="application/x-dtbncx+xml" />
</manifest>
<spine toc="ncx">
<itemref idref="intro" />
<itemref idref="c1" />
<itemref idref="c1-answerkey" linear="no" />
<itemref idref="c2" />
<itemref idref="c2-answerkey" linear="no" />
<itemref idref="c3" />
<itemref idref="c3-answerkey" linear="no" />
<itemref idref="note" linear="no" />
</spine>
In the above example, the publication author set linear="no" on four of the eight OPS Content Documents listed in
spine, designating these content documents to be
auxiliary. Three of the four are "answer keys," and the fourth is a note of some sort;
all four are auxiliary to the main flow of the book and may be viewed separately from
the main flow.
Reading Systems which recognize and render auxiliary content separate from primary
content will set the main reading order to be the four primary OPS Content Documents:
intro, c1,
c2 and c3. The
auxiliary content documents will be rendered by such Reading Systems, upon activation
(such as through a hypertext link or entry in NCX), in some manner distinct from the
main reading order. It is important that the publication author provide the necessary
references to the auxiliary content documents, otherwise this content might not be
reachable in some auxiliary-aware Reading Systems.
Reading Systems which opt to ignore linear="no" and
set all itemref to be primary, as allowed in this
specification, will assign all eight OPS Content Documents to the main reading order in
the order given. This is especially useful for Reading Systems which provide print
output, where it is important that all the information in the OPS Content Documents be
printed in an author-determined linear order.
A Reading System may, at its discretion, provide both
rendering options to the user.
In order to enable ease of navigation and provide greater accessibility, the OPF
Package Document supports a "Navigation Center eXtended," the NCX. This is a concept
and implementation that has been standardized by the DAISY Consortium.
This specification uses the NCX defined in the DAISY/NISO Standard, formally the
ANSI/NISO Z39.86-2005, Specifications for the Digital
Talking Book. The NCX is a portion (Section 8) of this comprehensive
multimedia standard. The DAISY Consortium maintains the NCX DTD. No modifications to
the DTD are necessary for use with OPF. In the future the DAISY/NISO Advisory
Committee will consider modularizing the NCX and changing terminology to be more in
line with ebooks, multimedia publications and other electronic document usage.
Some optional elements and metadata items are not needed to
implement the NCX for this specification. The sections below have been changed to
normatively reference the DAISY/NISO standard for the NCX rather than duplicating it
here. All "exceptions" are described in Section 2.4.2, below.
The Navigation Control file for XML applications (NCX) exposes the hierarchical
structure of a Publication to allow the user to navigate through it. The NCX is
similar to a table of contents in that it enables the reader to jump directly to
any of the major structural elements of the document, i.e. part, chapter, or
section, but it will often contain more elements of the document than the publisher
chooses to include in the original print table of contents. It can be visualized as
a collapsible tree familiar to PC users. Its development was motivated by the need
to provide quick access to the main structural elements of a document without the
need to parse the entire documents. Other elements such as pages, footnotes,
figures, tables, etc. can be included in separate, nonhierarchical lists and can be
accessed by the user as well(see the below informative example).
It is important to emphasize that these navigation features are intended as a
convenience for users who want them, and not a burden to those who do not. The
alternative guide to the book may be provided for
those users not requiring the navigation features of the NCX.
Reading Systems must support NCX.
OPS Publications must include an NCX.
OPS Publications must include an NCX.
Reading Systems should support the NCX.
A Reading System should have the ability to, at user selection,
provide access to the NCX navMap in a fashion that
allows the user to activate the links provided in the navMap,
thus relocating the application's current reading position to the destination described
by the selected NCX navPoint.
The behavioral expectations described above apply to the NCX pageList
and navList as well, if the given NCX contains said elements.
Reading System implementors should be aware that in a forthcoming major revision of the
EPUB specification, it likely will become a compliance criteria for Reading Systems to support the
NCX navMap, pageList and
navList as described above.
Like all other Publication components, the NCX must be
included as an item in the manifest (with media-type of
application/x-dtbncx+xml). The NCX-referencing
item must not contain any
fallback information (required-namespace,
fallback or fallback-style attributes).
If a Publication includes an NCX, theThe item that
describes the NCX must be referenced by the spine toc attribute.
The NCX file must be a valid XML document conforming to
ncx-2005-1.dtd and comply with the additional normative
requirements defined in http://www.niso.org/standards/resources/Z39-86-2005.html
, with the exception of the playOrder attribute, which is optional in EPUB NCX.
The version and xmlns attributes on the ncx
element must be explicitly specified in the document
instance, using values drawn from the above-named DTD.
Any NCX that contains a DOCTYPE that references the canonical NCX
DTD must honor that DTD, thus including the
playOrder attribute in all locations
where it is required. NCX documents that do not contain a DOCTYPE
may omit the
playOrder attribute.
navMap is a required element
in the NCX; it provides navigational access to the major hierarchical structure of the publication.
pageList must be included if the publication
is designed to allow the user to navigate to pages. One or several navList's
may be included to allow navigation to other arbitrary constructs in
the content (see the below informative example).
The URI specified by the src of the content element for
navMap, pageList, and
navList elements must resolve to OPS
Content Document fragments.
Example illustrating an NCX with a navMap, a pageList, and a navList containing a list of illustrations:
<ncx xmlns="http://www.daisy.org/z3986/2005/ncx/" version="2005-1" xml:lang="en-US">
<head>
<meta content="org-example-5059463624137734586" name="dtb:uid"/>
</head>
<docTitle>
<text>Selections from "Great Pictures, As Seen and Described by Famous Writers"</text>
</docTitle>
<docAuthor>
<text>Esther Singleton</text>
</docAuthor>
<navMap>
<navPoint class="h1" id="ch1">
<navLabel>
<text>Chapter 1</text>
</navLabel>
<content src="content.html#ch_1"/>
<navPoint class="h2" id="ch_1_1">
<navLabel>
<text>Chapter 1.1</text>
</navLabel>
<content src="content.html#ch_1_1"/>
</navPoint>
</navPoint>
<navPoint class="h1" id="ncx-2">
<navLabel>
<text>Chapter 2</text>
</navLabel>
<content src="content.html#ch_2"/>
</navPoint>
</navMap>
<pageList>
<pageTarget id="p1" type="normal" value="1">
<navLabel><text>1</text></navLabel>
<content src="content.html#p1"/>
</pageTarget>
<pageTarget id="p2" type="normal" value="2">
<navLabel><text>2</text></navLabel>
<content src="content.html#p2"/>
</pageTarget>
</pageList>
<navList>
<navLabel>
<text>List of Illustrations</text>
</navLabel>
<navTarget id="ill-1">
<navLabel><text>Portratit of Georg Gisze (Holbein)</text></navLabel>
<content src="content.html#ill1"/>
</navTarget>
<navTarget id="ill-2">
<navLabel><text>The adoration of the lamb (Van Eyck)</text></navLabel>
<content src="content.html#ill2"/>
</navTarget>
</navList>
</ncx>
The NCX as defined in the ANSI/NISO Z39.86-2005 Standard Section 8 is ideal for OPS
applications, however, some exceptions are noted herein. In the standard, the links
from the NCX to the Publication point to SMIL (http://www.w3.org/TR/2005/REC-SMIL2-20050107/)
documents. For OPS Publications, the links will point to an XML elements in the
source OPS Content Document. This difference causes the following exceptions to be
noted from Section 8 in that standard:
-
smilCustomTest is not used in the OPF application of
the NCX;
-
audio is not used in the OPS application of the NCX;
-
clipBegin (%SMILtimeVal, REQUIRED): is used
for identifying the start of an audio segment, and hence not used in the OPF
application of the NCX;
-
clipEnd (%SMILtimeVal, REQUIRED): is used
for identifying the end of an audio segment, and hence not used in the OPF
application of the NCX;
-
content Description: Pointer into SMIL file to
beginning of the item referenced by the navPoint or
navTarget. Note: In the OPF application of the NCX the
pointer is to an XML element and not a SMIL location.
- DTBs Spanning Multiple Media Units are not relevant in the Publication context
because OPS Publications are significantly smaller than multimedia files.
- Examples show links to SMIL files, but in the OPF application of NCX the links
will be to XML elements. Also, the examples show audio
references with clipBegin and
clipEnd, which are not used in the OPF application of the NCX.
-
The required NCX metadata items "dtb:totalPageCount" and "dtb:maxPageNumber"
may not be relevant when content is not related to a rendition with "paper pages".
In this case, their values may be specified as zero and
the Reading System may ignore them.
The list of required metadata provided in http://www.niso.org/workrooms/daisy/Z39-86-2005.html#NavMeta
does not apply to EPUB; the only required meta is that
which contains a content reference to the OPF unique ID. For
backwards compatibility reasons, the value of the name of that
meta remains dtb:id.
-
playOrder attributes
remain requiredare
not required. Although
playOrder attributes are not used to sequence SMIL
content, if present, they should contain valid values that reflect the
linear document reading order. This could, for example, be used when one is
navigating a pageList to find a corresponding location
in the navMap.
XML Islands may be referenced
from the spine. In the event that a Reading System cannot display the XML Island
correctly, then the standard fallback methodology defined in the Open Publication Structure must be used.
In short, the Reading System must display the chosen
fallback for an XML Island in the event that the
island itself cannot be displayed.
Much as a tour-guide might assemble points of interest into a set of sightseers' tours,
a content provider could assemble selected parts of a publication into a set of tours
to enable convenient navigation.
An OPS Package Document may, but need not, contain one
tours element, which in turn contains one or more
tour elements. Each tour
must have a title attribute,
intended for presentation to the user. Reading Systems may use
tours to provide various access sequences to parts of the
publication, such as selective views for various reading purposes, reader expertise
levels, etc. Because Reading Systems are not required to
implement tour support, content providers should also provide
other means of accessing content referenced from tours.
Each tour element contains one or more site elements, each of which must have an
href attribute and a title attribute. The href attribute
must refer to an OPS Content Document included in the
manifest, and may include a
fragment identifier as defined in section 4.1 of RFC 2396 (see http://www.ietf.org/rfc/rfc2396.txt). Each site element specifies a starting point from which the reader can
explore freely. Reading Systems may use the bounds of the
referenced element to determine the scope of the site. If a fragment identifier is
not used, the scope is considered to be the entire document. This specification does
not require Reading Systems to mark or otherwise identify
the entire scope of a referenced element. The order of site elements is presumed to be significant, and should be used by Reading Systems to aid navigation.
For example:
<tours>
<tour id="tour1" title="Chicken Recipes">
<site title="Chicken Fingers"
href="appetizers.html#r3" />
<site title="Chicken a la King"
href="entrees.html#r5" />
</tour>
<tour id="tour2" title="Vegan Recipes">
<site title="Hummus" href ="appetizer.html#r6" />
<site title="Lentil Casserole" href="lentils.html" />
</tour>
</tours>
Within the package there may be one guide element, containing one or more reference elements. The guide element
identifies fundamental structural components of the publication, to enable Reading
Systems to provide convenient access to them.
For example:
<guide>
<reference type="toc" title="Table of Contents"
href="toc.html" />
<reference type="loi" title="List Of Illustrations"
href="toc.html#figures" />
<reference type="other.intro" title="Introduction"
href="intro.html" />
</guide>
The structural components of the books are listed in reference elements contained within the guide element. These components could refer to the table of contents,
list of illustrations, foreword, bibliography, and many other standard parts of the
book. Reading Systems are not required to use the guide element in any way.
Each reference must have an href attribute referring to an OPS Content Document included in the
manifest, and which may include a
fragment identifier as defined in section 4.1 of RFC 2396 (see hhttp://www.ietf.org/rfc/rfc2396.txt). Reading Systems
may use the bounds of the referenced element to determine
the scope of the reference. If a fragment identifier is not used, the scope is
considered to be the entire document. This specification does not
require Reading Systems to mark or otherwise identify the entire scope of a
referenced element.
The required type attribute
describes the publication component referenced by the href attribute. The values for the type attributes must be selected from the
list defined below when applicable. Other types may be used
when none of the predefined types are applicable; their
names must begin with the string other.. The value for the type
attribute is case-sensitive.
The following list of type values is derived from the
13th edition of the Chicago Manual of Style:
|
cover
|
the book cover(s), jacket information, etc.
|
|
title-page
|
page with possibly title, author, publisher, and other metadata
|
|
toc
|
table of contents
|
|
index
|
back-of-book style index
|
|
glossary
|
|
|
acknowledgements
|
|
|
bibliography
|
|
|
colophon
|
|
|
copyright-page
|
|
|
dedication
|
|
|
epigraph
|
|
|
foreword
|
|
|
loi
|
list of illustrations
|
|
lot
|
list of tables
|
|
notes
|
|
|
preface
|
|
|
text
|
First "real" page of content (e.g. "Chapter 1")
|
