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<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-US">
<head>
<meta charset="utf-8" />
<title>Web Publications</title>
<script src="https://www.w3.org/Tools/respec/respec-w3c-common" class="remove" defer="defer"></script>
<script src="common/js/biblio.js" class="remove"></script>
<script src="common/js/wp.js" class="remove"></script>
<script src="common/js/parts.js" class="remove"></script>
<script src="common/js/idllink.js" class="remove"></script>
<link href="common/css/common.css" rel="stylesheet" type="text/css" />
<script class="remove">
// <![CDATA[
var respecConfig = {
postProcess: [create_wp, denumber_parts, convert_dfn_to_link],
wg: "Publishing Working Group",
specStatus: "ED",
shortName: "wpub",
previousPublishDate: "2019-06-14",
previousMaturity: "WD",
edDraftURI: "https://w3c.github.io/wpub/",
editors: [
{
"name": "Matt Garrish",
"company": "DAISY Consortium",
"companyURL": "http://www.daisy.org",
"w3cid": 51655
},
{
"name": "Ivan Herman",
"url": "https://www.w3.org/People/Ivan/",
"company": "W3C",
"w3cid": 7382,
"orcid": "0000-0003-0782-2704",
"companyURL": "https://www.w3.org",
}
],
processVersion: 2018,
includePermalinks: false,
permalinkEdge: true,
permalinkHide: false,
diffTool: "http://www.aptest.com/standards/htmldiff/htmldiff.pl",
wgURI: "https://www.w3.org/publishing/groups/publ-wg/",
wgPublicList: "public-publ-wg",
wgPatentURI: "https://www.w3.org/2004/01/pp-impl/100074/status",
github: {
repoURL: "https://github.com/w3c/wpub/",
branch: "master"
},
localBiblio: localBiblio
};
// ]]>
</script>
<style>
var {
color: brown;
}
code.json {
color: teal;
}</style>
</head>
<body>
<section id="abstract">
<p>The primary objective of this specification is to define requirements for the production of <a>Web
Publications</a>. In doing so, it also defines a framework for creating packaged publication
formats, such as EPUB and audiobooks, where a pathway to the Web is highly desirable but not necessarily
the primary method of interchange or consumption.</p>
</section>
<section id="sotd">
<p>Due to the lack of practical business cases for Web Publications, and the consequent lack of commitment
to implement the technology, the <a href="https://www.w3.org/publishing/groups/publ-wg/">Publishing
Working Group</a> has chosen to publish this document as a Note and focus on other areas of
interest, including developing the manifest format as a separate specification.</p>
<p>This document was still a work in progress at the time of its publication. As a result, anyone seeking to
create Web Publications, or implement a reader for them, should read the approach and proposals outlined
in this document with an abundance of caution. It is being published to archive the work and allow
incubation, should interest emerge in the future to resume its development.</p>
<p>The following aspects of the specification, in particular, were being actively discussed at the time of
publication and are considered incomplete or in need of more review:</p>
<ul>
<li>the nature of the canonical identifier;</li>
<li>whether or not the address should specify a specific resource or only refer to a directory (i.e.,
rely on a default document being served);</li>
<li>differences in linking from the primary entry page to the manifest and from a publication resource
to the primary entry page; and</li>
<li>the processing of the manifest, in particular the inheritance of information from the primary entry
page (e.g., title or language information).</li>
</ul>
<p>As well, reviews of the following areas were intended to be undertaken only when the specification
stabilized:</p>
<ul>
<li>security, such as issues around cross-origin resource sharing and the exact origin for Web
Publication resources;</li>
<li>privacy, both as it relates to the maintenance of stored content and user-identifiable information;
and</li>
<li>user agent implementation of features.</li>
</ul>
</section>
<section id="intro">
<h2>Introduction</h2>
<section id="scope">
<h3>Scope</h3>
<p>This specification defines three key concepts:</p>
<ol>
<li>a general manifest format to describe publications;</li>
<li>a concrete format using the manifest to represent publications on the Web (<a>Web
Publications</a>); and</li>
<li>the rules for using the manifest as the basis for modular extensions that desire a pathway to
the Web.</li>
</ol>
<p>This specification does not attempt to constrain the nature of the publications that can be
produced—any type of work that can be represented using Web technologies is in scope. It is also
designed to be adaptable to the needs of specific areas of publishing, such as audiobook production,
and encourages a modular approach for creating specializations.</p>
<p>As much as possible, this specification leverages existing Open Web Platform technologies to achieve
its goal—that being to allow for a measure of boundedness — on and off the Web — without changing
the way that the Web itself operates.</p>
<p>Moreover, this specification is designed to adapt automatically to updates to Open Web Platform
technologies in order to ensure that conforming publications continue to interoperate seamlessly as
the Web evolves (e.g., by referencing the latest published versions instead of specific dated
versions).</p>
<p>This specification is also intended to facilitate different user agent architectures for the
consumption of Web Publications, or any format derived therefrom. While a primary goal is that
traditional Web user agents (browsers) will be able to consume Web Publications, this should not
limit the capabilities of any other possible type of user agent (e.g., applications, whether
standalone or running within a user agent, or even Web Publications that include their own user
interface). As a result, the specification does not attempt to architect required solutions for
situations whose expected outcome will vary depending on the nature of the user agent and the
expectations of the user (e.g., how to prompt to initiate a Web Publication, or at what point or how
much of a Web Publication to cache for offline use).</p>
<p>This specification does not define how user agents are expected to render Web Publications. Details
about the types of afforances that user agents can provide to enhance the reading experience for
users are instead defined in [[PWP-UCR]].</p>
</section>
<section id="org" class="informative">
<h3>Organization</h3>
<p>This specification organized into three distinct parts, each of which builds on the previous:</p>
<dl>
<dt><a href="#manifest">Part I — Publication Manifest</a></dt>
<dd>
<p>The first part of this specification defines a general manifest format for expressing
information about a <a>digital publication</a>. It uses [[schema.org]] metadata augmented to
include various structural properties about publications, and is serialized in [[JSON-LD]].
This definition is designed to be the basis for all the specific implementations of digital
publications. It allows for interoperability between the formats while accommodating
variances in the information that needs to be expressed. The actual manifest requirements
for a digital publication format are defined by its respective specification.</p>
</dd>
<dt><a href="#webpub">Part II — Web Publications</a></dt>
<dd>
<p>The second part of this specification details the Web Publications format for defining and
deploying publications on the Web. It explains the requirements for expressing the Web
Publication manifest, as well as various implementation details such as the primary entry
page and the table of contents. Web Publications are the Web deployment format for all
digital publications based on a Publication Manifest, so all such extensions have to remain
compatible with the requirements defined in this section.</p>
</dd>
<dt><a href="#extensions">Part III — Modular Extensions</a></dt>
<dd>
<p>The third part of this specification defines how create new packaged digital publication
formats using the Publication Manifest model. While such formats are not required to be
conforming Web Publications in their native state, it has to be possible to create content
that can conform to both requirements.</p>
</dd>
</dl>
</section>
<section id="terminology">
<h3>Terminology</h3>
<p>This document uses terminology defined by the W3C Note "Publishing and Linking on the
Web" [[publishing-linking]], including, in particular, <a class="externalDFN"
href="https://www.w3.org/TR/publishing-linking/#dfn-user">user</a>, <a class="externalDFN"
href="https://www.w3.org/TR/publishing-linking/#dfn-user-agent">user agent</a>, <a
class="externalDFN" href="https://www.w3.org/TR/publishing-linking/#dfn-browser">browser</a>,
and <a class="externalDFN" href="https://www.w3.org/TR/publishing-linking/#dfn-address"
>address</a>.</p>
<dl>
<dt>
<dfn data-lt="digital publications|digital publication's">Digital Publication</dfn>
</dt>
<dd>
<p>The term digital publication is used to refer to the encoding of a publication in any format
that conforms to this specification, whether a <a>Web Publication</a> or a <a
href="#extensions">modular extension</a>. All such digital publications share the common
<a>manifest</a> format, but differ in their structural and content requirements.</p>
</dd>
<dt>
<dfn data-lt="Manifests">Manifest</dfn>
</dt>
<dd>
<p>A manifest represents structured information about a publication, such as informative
metadata, a <a href="#resource-list">list of all resources</a>, and a <a>default reading
order</a>.</p>
</dd>
<dt>
<dfn>Non-empty</dfn>
</dt>
<dd>
<p>For the purposes of this specification, non-empty is used to refer to an element, attribute
or property whose text content or value consists of one or more characters after whitespace
normalization, where whitespace normalization rules are defined per the host format.</p>
</dd>
<dt>
<dfn data-lt="Web Publications|Web Publication's">Web Publication</dfn>
</dt>
<dd>
<p>A Web Publication is a collection of one or more resources, organized together through a
<a>manifest</a> into a single logical work with a <a>default reading order</a>. The Web
Publication is uniquely identifiable and presentable using Open Web Platform
technologies.</p>
</dd>
</dl>
</section>
<section id="conformance"></section>
</section>
<section id="manifest" class="part">
<h2>PART I: Publication Manifest</h2>
<section id="manifest-intro" class="informative">
<h3>Introduction</h3>
<p>A <a>digital publication</a> is described by its <a>manifest</a>, which provides a set of properties
expressed using the JSON-LD [[json-ld]] format (a variant of JSON [[ecma-404]] for linked
data).</p>
<p>The manifest includes both descriptive properties about the publication, such as its title and
author, as well as information about the nature and structure of the publication.</p>
<p>This section describes the construction requirements for manifests, and outlines the general set of
properties for use with them.</p>
</section>
<section id="manifest-authored-canonical" class="informative">
<h3>Authored and Canonical Manifests</h3>
<p>Depending on the state of a <a>digital publication</a>, its manifest exists in one of two forms:</p>
<dl>
<dt>
<dfn data-lt="authored publication manifest">Authored Manifest</dfn>
</dt>
<dd>
<p>The Authored Publication Manifest is the serialization of the manifest that the author
provides with the digital publication (i.e., prior to be digital publication being processed
by a user agent). Note that the author does not have to be human; a machine could
automatically produce authored manifests for digital publications.</p>
</dd>
<dt>
<dfn data-lt="canonical manifest|canonical publication manifest">Canonical Manifest</dfn>
</dt>
<dd>
<p>The Canonical Publication Manifest is a version of the manifest created by user agents when
they <a href="#processing-manifest">process the authored manifest</a> and remove all
possible ambiguities and incorporate any missing values that can be inferred from another
source.</p>
</dd>
</dl>
<p>It is possible that an authored manifest is the equivalent of the canonical manifest if there are no
ambiguities or missing information, but a canonical manifest only exists after a user agent has
inspected the authored manifest as part of the process of obtaining it.</p>
<p>This part of the specification describes the requirements for creating an authored manifest,
regardless of the format of the digital publication. Rules for constructing a canonical manifest
from the authored manifest are defined for each specific implementation (e.g., the process for
<a>Web Publications</a> is described in <a href="#canonical-manifest"></a>).</p>
</section>
<section id="webidl">
<h3>Web IDL</h3>
<p>Although a <a>digital publication</a>'s manifest is authored as [[json-ld]], a user agent processes
this information into an internal data structure, which can be in any language, in order to utilize
the properties. The exact manner in which this processing occurs, and how the data is used
internally, is user agent-dependent and not defined in this specification.</p>
<p>To simplify the understanding of the manifest format for developers, this specification defines an
abstract representation of the data structures employed by the manifest using the Web Interface
Definition Language (Web IDL) [[webidl-1]] — <a href="#webidl-wpm">the
<code>PublicationManifest</code> dictionary</a>.</p>
<p>This definition expresses the expected names, datatypes, and possible restrictions for each member of
the manifest. Unlike a typical Web IDL definition, however, user agents are not expected to expose
the information in the manifest as an API. The Web IDL language is chosen solely to provide an
abstraction of the data model.</p>
<p class="note">It is not necessary to understand the Web IDL definition in order to create digital
publications. Authoring requirements are defined in the following sections.</p>
<section id="webidl-wpm">
<h4>The <dfn><code>PublicationManifest</code></dfn> Dictionary</h4>
<pre class="idl" id="wpm">
dictionary PublicationManifest {
required sequence<DOMString> type;
sequence<DOMString> id;
sequence<DOMString> accessMode;
sequence<DOMString> accessModeSufficient;
sequence<DOMString> accessibilityFeature;
sequence<DOMString> accessibilityHazard;
LocalizableString accessibilitySummary;
sequence<CreatorInfo> artist;
sequence<CreatorInfo> author;
sequence<CreatorInfo> colorist;
sequence<CreatorInfo> contributor;
sequence<CreatorInfo> creator;
sequence<CreatorInfo> editor;
sequence<CreatorInfo> illustrator;
sequence<CreatorInfo> inker;
sequence<CreatorInfo> letterer;
sequence<CreatorInfo> penciler;
sequence<CreatorInfo> publisher;
sequence<CreatorInfo> readBy;
sequence<CreatorInfo> translator;
sequence<DOMString> url;
DOMString duration;
DOMString inLanguage;
TextDirection inDirection;
DOMString dateModified;
DOMString datePublished;
ProgressionDirection readingProgression = "ltr";
required sequence<LocalizableString> name;
required sequence<LinkedResource> readingOrder;
sequence<LinkedResource> resources = [];
sequence<LinkedResource> links = [];
};
dictionary CreatorInfo {
sequence<DOMString> type;
required sequence<LocalizableString> name;
DOMString id;
DOMString url;
};
enum TextDirection {
"ltr",
"rtl",
"auto"
};
dictionary LocalizableString {
required DOMString value;
DOMString language;
};
enum ProgressionDirection {
"ltr",
"rtl"
};
</pre>
</section>
</section>
<section id="manifest-context">
<h3>Manifest Contexts</h3>
<p>A <a>digital publication's</a>
<a>manifest</a> MUST start by setting the JSON-LD context [[!json-ld]]. The context has the
following two major components:</p>
<ul>
<li>the [[!schema.org]] context: <code>https://schema.org</code></li>
<li>the publication context: <code>https://www.w3.org/ns/wp-context</code></li>
</ul>
<pre class="example" title="The context declaration.">
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/wp-context"],
…
}
</pre>
<p>The publication context document adds features to the properties defined in Schema.org (e.g., the
requirement for the <a href="https://schema.org/creator">creator</a> property to be order
preserving).</p>
<p class="ednote">As part of the continuous contacts with Schema.org the additional features defined in
the publication context file could migrate to the core Schema.org vocabulary.</p>
<p class="note">Although Schema.org is often referenced using the <code>http</code> URI scheme, <a
href="https://schema.org/docs/faq.html#19">the vocabulary is being migrated</a> to use the
secure <code>https</code> scheme as its default. This specification requires the use of
<code>https</code> when referencing Schema.org in the manifest.</p>
</section>
<section id="publication-types">
<h4>Publication Types</h4>
<p>A <a>digital publication's</a>
<a>manifest</a> MUST define its <dfn>Publication Type</dfn> using the <code
data-dfn-for="PublicationManifest"><dfn>type</dfn></code> term [[!json-ld]]. The type MAY
be mapped onto <a href="https://schema.org/CreativeWork"
><code>CreativeWork</code></a> [[!schema.org]].</p>
<pre class="example" title="Setting a publication's type to CreativeWork.">
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/wp-context"],
"type" : "CreativeWork",
…
}
</pre>
<p>Schema.org also includes a number of more specific subtypes of <code>CreativeWork</code>, such as <a
href="https://schema.org/Article"><code>Article</code></a>, <a href="https://schema.org/Book"
><code>Book</code></a>, <a href="https://schema.org/TechArticle"
><code>TechArticle</code></a>, and <a href="https://schema.org/Course"><code>Course</code></a>.
These MAY be used instead of, or in addition to, <code>CreativeWork</code>.</p>
<pre class="example" title="Setting a publication's type to Book.">
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/wp-context"],
"type" : "Book",
…
}
</pre>
<p>Each Schema.org type defines a set of properties that are valid for use with it. To ensure that the
manifest can be validated and processed by Schema.org aware processors, the manifest SHOULD contain
only the properties associated with the selected type.</p>
<p>If properties from more than one type are needed, the manifest MAY include multiple type
declarations.</p>
<pre class="example" title="A publication that combines properties from both Book and VisualArtwork.">
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/wp-context"],
"type" : ["Book", "VisualArtwork"],
…
}
</pre>
<p>User agents SHOULD NOT fail to process manifests that are not valid to their declared Schema.org
type(s).</p>
<p class="note">Refer to the Schema.org site for the complete <a href="https://schema.org/CreativeWork"
>list of <code>CreativeWork</code> subtypes</a>.</p>
</section>
<section id="manifest-properties">
<h3>Properties</h3>
<section id="properties-intro" class="informative">
<h4>Introduction</h4>
<p>A <a>digital publication's</a>
<a>manifest</a> is defined by a set of properties that describe the basic information a user
agent requires to process and render the publication. These properties are categorized as
followed:</p>
<dl>
<dt>
<a href="#descriptive-properties">descriptive properties</a>
</dt>
<dd>
<p>Descriptive properties describe aspects of a digital publication, such as its <a
href="#pub-title">title</a>, <a href="#creators">creator</a>, and <a
href="#language-and-dir">language</a>. These properties are primarily drawn from <a
href="https://schema.org">Schema.org</a> and its <a
href="https://schema.org/docs/schemas.html">hosted
extensions</a> [[schema.org]], so they map to one or several Schema.org properties
and inherit their syntax and semantics. (The following property categories typically do
not have Schema.org equivalents, so are defined specifically for publications.)</p>
</dd>
<dt>
<a href="#resource-categorization-properties">resource categorization</a>
</dt>
<dd>
<p>Resource categorization properties describe or identify common sets of resources, such as
the <a href="#resource-list">resource list</a> and <a href="#default-reading-order"
>default reading order</a>. These properties refer to one or more resources, such as
HTML documents, images, script files, and separate metadata files.</p>
</dd>
</dl>
<p class="note">The categorization of properties exists only to simplify comprehension of their
purpose; the groupings have no relevance outside this specification (i.e., the properties are
not actually grouped together in the manifest).</p>
<div class="note">
<p>Each manifest item drawn from schema.org identifies the property it maps to and includes its
defining type in parentheses. Properties are often available in many types, however, as a
result of the schema.org inheritance model. Refer to each property definition for more
detailed information about where it is valid to use.</p>
<p>Schema.org additionally includes a large number of properties that, though relevant for
publishing, are not mentioned in this specification — publication authors can use any of
these properties. This document defines only the minimal set of manifest items.</p>
</div>
<p class="ednote">There are discussion on whether a best practices document would be created,
referring to more schema.org terms. If so, it should be linked from here.</p>
</section>
<section id="properties-value-categories">
<h4>Value Categories</h4>
<p>This section describes the categories of values that can be used with properties of the
Publication Manifest.</p>
<section id="value-literal">
<h5>Literals</h5>
<p>Some <a href="#manifest-properties">manifest</a> properties expect a literal text string as
their value — one that is not language-dependent, such as a code value or date. These
values are expressed as [[!json]] strings.</p>
<p>Literal values are not changed <a href="#canonical-manifest">during canonicalization of the
manifest</a>, unlike other values which might be, for example, converted to objects.</p>
</section>
<section id="value-number">
<h5>Numbers</h5>
<p> Some <a href="#manifest-properties">manifest</a> properties expect a number as their value.
These values are expressed as [[!json]] numbers. </p>
</section>
<section id="value-objects">
<h5>Explicit and Implied Objects</h5>
<p>Various manifest properties are expected to be expressed as [[!json]] objects. Although
the use of objects is usually recommended, it is also acceptable to use string values that
are interpreted as objects depending on the context. The exact mapping of text values to
objects is part of the property or object definitions.</p>
<section id="value-localizable-string">
<h5>Localizable Strings</h5>
<p>Some <a href="#manifest-properties">manifest</a> properties expect a localizable text
string as their value. These values are expressed either as:</p>
<ul>
<li>a single string value;</li>
<li>an anonymous object with a <code>value</code> property containing a the property's
text and a <code>language</code> property that identifies the language of the
text.</li>
</ul>
<p>In the case of single string values, these represent a implied object whose
<code>value</code> property is the string's text and whose language will be
determined from other information in the manifest.</p>
</section>
<section id="value-object-entity">
<h6>Entities</h6>
<p>A common case of implied objects in the Publication Manifest properties set is for <a
href="#creators">creators</a>. The entities responsible for the various aspects of
creation are expressed as [[!schema.org]] <a href="https://schema.org/Person">Person</a>
and/or <a href="https://schema.org/Organization">Organization</a> objects. To simplify
authoring, however, a simple string value can be used for the entity's name. In this
case, the entity is assumed to represent a Person.</p>
<aside class="example" title="Using a text string instead of a Person object.">
<p>The following author name is expressed as a text string:</p>
<pre>
{
"author" : "Herman Melville",
…
}</pre>
<p>but, in the context of <a href="#creators">creators</a>, it is equivalent to:</p>
<pre>
{
"author" : {
"type" : "Person",
"name" : "Herman Melville"
},
…
}</pre>
<p>(See <a href="#creators"></a> for further details.)</p>
</aside>
</section>
<section id="value-link">
<h5>Links</h5>
<p>With the exception of the <a href="#descriptive-properties">descriptive properties</a>,
manifest properties typically link to one or more resources. When a property requires a
link value, the link MUST be expressed in one of the following two ways:</p>
<ol>
<li>as a string encoding the <a>URL</a> of the resources; or</li>
<li>as an instance of a <a href="#publication-link-def"><code>LinkedResource</code>
object</a> that can be used to express the URL, the media type, and other
characteristics of the target resource.</li>
</ol>
<p>In the case of single string values, these represent an implied
<code>LinkedResource</code> object whose <code>url</code> property is set to that
string value.</p>
<pre class="example" title="Resource list that includes one link using a relative URL as a string ('datatypes.svg') and two that display the various properties of the a LinkedResource object">
{
…
"resources" : [
"datatypes.svg",
{
"type" : "LinkedResource",
"url" : "test-utf8.csv",
"encodingFormat" : "text/csv",
"name" : "Test Results",
"description" : "CSV file containing the full data set used."
},
{
"type" : "LinkedResource",
"url" : "terminology.html",
"encodingFormat" : "text/html",
"rel" : "glossary"
}
]
}
</pre>
</section>
</section>
<section id="value-url">
<h5>URLs</h5>
<p><dfn data-lt="URL">URLs</dfn> are used to identify resources associated with a <a>digital
publication</a>. They MUST be <a href="https://url.spec.whatwg.org/#absolute-url-string"
>valid URL strings</a> [[!url]].</p>
<p>Manifest URLs are restricted to only the <code>http</code> and <code>https</code>
<a href="https://url.spec.whatwg.org/#concept-url-scheme">schemes</a> [[!url]]. URLs MUST
dereference to a resource, although user agents are not required to dereference all URLs in
the manifest.</p>
<p>In the case of <a href="https://url.spec.whatwg.org/#relative-url-string">relative-URL
strings</a>, these are resolved to <a
href="https://url.spec.whatwg.org/#absolute-url-string">absolute-URL strings</a> using a
<a href="https://url.spec.whatwg.org/#concept-base-url">base URL</a> [[!url]].</p>
<p>The base URL for relative-URL strings is determined as follows:</p>
<ul>
<li>In the case of an <a href="#manifest-embed">embedded manifest</a>, the base URL is the
<a data-cite="!html#the-base-element">document base URL</a> [[!html]] of the
<a>primary entry page</a> of the publication;</li>
<li>In the case of a <a href="#manifest-link">linked manifest</a>, the base URL is URL of
the manifest resource.</li>
</ul>
<p>By consequence, relative-URL strings in embedded manifests are resolved against the URL of
the primary entry page <em>unless</em> the page declares a base URL (i.e., in a <a
data-cite="!html#the-base-element"><code><base></code> element</a> in its
header).</p>
<p class="note">URLs allow for the usage of characters from Unicode following [[rfc3987]].
See <a href="https://www.w3.org/TR/html/references.html#biblio-url">the note in the HTML5
specification</a> for further details.</p>
</section>
<section id="value-id">
<h5>Identifiers</h5>
<p>Identifiers are <a href="https://url.spec.whatwg.org/#concept-url">URL records</a> [[!url]]
that can be used to refer to <a class="externalDFN"
href="https://www.w3.org/TR/publishing-linking/#dfn-web-content">Web Content</a> in a
persistent and unambiguous manner. <abbr title="Uniform Resource Locators">URLs</abbr>,
<abbr title="Uniform Resource Names">URNs</abbr>, <abbr
title="Digital Object Identifiers">DOIs</abbr>, <abbr
title="International Standard Book Numbers">ISBNs</abbr>, and <abbr
title="Persistent Uniform Resource Locators">PURLs</abbr> are all examples of persistent
identifiers frequently used in publishing.</p>
</section>
<section id="value-array">
<h5>Arrays</h5>
<p>Some <a href="#manifest-properties">manifest properties</a> allow one or more value of their
respective type (<a href="#value-literal">literal</a>, <a href="#value-objects">object</a>,
or <a href="#value-url">URL</a>). As a general rule, these values can be expressed as
[[!json]] arrays. When the property value is an array with a single element, however,
the array syntax MAY be omitted.</p>
<aside class="example" title="Using a text string instead of an array">
<p>As a digital publication typically contains many resources, this declaration of a single
resource:</p>
<pre>
{
"resources" : "datatypes.svg",
…
}</pre>
<p>is equivalent to the array:</p>
<pre>
{
"resources" : ["datatypes.svg"],
…
}</pre>
</aside>
</section>
</section>
<section id="descriptive-properties">
<h4>Descriptive Properties</h4>
<section id="accessibility">
<h5>Accessibility</h5>
<p>The accessibility properties provides information about the suitability of a <a>digital
publication</a> for consumption by users with varying preferred reading modalities.
These properties typically supplement an evaluation against established accessibility
criteria, such as those provided in [[WCAG20]]. (For linking to a detailed accessibility
report, see <a href="#accessibility-report"></a>.)</p>
<p>The following properties are categorized as accessibility properties:</p>
<table class="zebra">
<thead>
<tr>
<th>Term</th>
<th>Description</th>
<th>Required Value</th>
<th>Value Category</th>
<th>[[!schema.org]] Mapping</th>
</tr>
</thead>
<tbody>
<tr>
<td>
<code data-dfn-for="PublicationManifest">
<dfn>accessMode</dfn>
</code>
</td>
<td> The human sensory perceptual system or cognitive faculty through which a person
may process or perceive information. </td>
<td>One or more text(s).</td>
<td>
<a href="#value-array">Array</a> of <a href="#value-literal">Literals</a>
</td>
<td>
<a href="https://schema.org/accessMode"><code>accessMode</code></a> (<a
href="https://schema.org/CreativeWork">CreativeWork</a>) </td>
</tr>
<tr>
<td>
<code data-dfn-for="PublicationManifest">
<dfn>accessModeSufficient</dfn>
</code>
</td>
<td> A list of single or combined accessModes that are sufficient to understand all
the intellectual content of a resource. </td>
<td> One or more <a href="https://schema.org/ItemList">ItemList</a>.</td>
<td>
<a href="#value-array">Array</a> of <a href="#value-literal">Literals</a>
</td>
<td>
<a href="https://schema.org/accessModeSufficient"
><code>accessModeSufficient</code></a> (<a
href="https://schema.org/CreativeWork">CreativeWork</a>) </td>
</tr>
<tr>
<td>
<code data-dfn-for="PublicationManifest">
<dfn>accessibilityFeature</dfn>
</code>
</td>
<td> Content features of the resource, such as accessible media, alternatives and
supported enhancements for accessibility. </td>
<td> One or more text(s).</td>
<td>
<a href="#value-array">Array</a> of <a href="#value-literal">Literals</a>
</td>
<td>
<a href="https://schema.org/accessibilityFeature"
><code>accessibilityFeature</code></a> (<a
href="https://schema.org/CreativeWork">CreativeWork</a>) </td>
</tr>
<tr>
<td>
<code data-dfn-for="PublicationManifest">
<dfn>accessibilityHazard</dfn>
</code>
</td>
<td> A characteristic of the described resource that is physiologically dangerous to
some users. </td>
<td> One or more text(s).</td>
<td>
<a href="#value-array">Array</a> of <a href="#value-literal">Literals</a>
</td>
<td>
<a href="https://schema.org/accessibilityHazard"
><code>accessibilityHazard</code></a> (<a
href="https://schema.org/CreativeWork">CreativeWork</a>) </td>
</tr>
<tr>
<td>
<code data-dfn-for="PublicationManifest">
<dfn>accessibilitySummary</dfn>
</code>
</td>
<td>A human-readable summary of specific accessibility features or deficiencies,
consistent with the other accessibility metadata but expressing subtleties such
as “short descriptions are present but long descriptions will be needed for
non-visual users” or “short descriptions are present and no long descriptions
are needed.” </td>
<td>Text.</td>
<td>
<a href="#value-localizable-string">Localizable String</a>
</td>
<td>
<a href="https://schema.org/accessibilitySummary"
><code>accessibilitySummary</code></a> (<a
href="https://schema.org/CreativeWork">CreativeWork</a>) </td>
</tr>
</tbody>
</table>
<p class="note">Detailed descriptions of these properties, including the expected values to use
with them, are available at [[webschemas-a11y]].</p>
<p class="note">The author can also provide a reference to a detailed <a
href="#accessibility-report">Accessibility Report</a> if more information is needed than
can be expressed by these properties.</p>
<pre class="example" title="Example accessiblity metadata for a document with text and images. The publication provides alternative text and long descriptions appropriate for each image, so can also be read in purely textual form.">
{
"@context" : ["https://schema.org","https://www.w3.org/ns/wp-context"],
"type" : "CreativeWork",
…
"accessMode" : ["textual", "visual"],
"accessModeSufficient" : [
{
"type" : "ItemList",
"itemListElement": ["textual", "visual"]
},
{
"type" : "ItemList",
"itemListElement": ["textual"]
}
],
…
}
</pre>
</section>
<section id="address">
<h4>Address</h4>
<p>A <a>digital publication's</a>
<dfn>address</dfn> is a <a>URL</a> that identifies its primary entry page. It is expressed
using the <code>url</code> property.</p>
<table class="zebra">
<thead>
<tr>
<th>Term</th>
<th>Description</th>
<th>Required Value</th>
<th>Value Type</th>
<th>[[!schema.org]] Mapping</th>
</tr>
</thead>
<tbody>
<tr>
<td>
<code data-dfn-for="PublicationManifest">
<dfn>url</dfn>
</code>
</td>
<td>URL of the primary entry page.</td>
<td>A valid URL string [[!url]].</td>
<td><a href="#value-array">Array</a> of <a href="#value-url">URLs</a></td>
<td>
<a href="https://schema.org/url"><code>url</code></a> (<a
href="https://schema.org/Thing">Thing</a>) </td>
</tr>
</tbody>
</table>
<p>A digital publication MAY have more than one address, but all the addresses MUST resolve to
the same document.</p>
<div class="note">The publication's address can also be used as value for an identifier link
relation [[link-relation]].</div>
<pre class="example" title="Setting the address of the main entry page">
{
"@context" : ["https://schema.org","https://www.w3.org/ns/wp-context"],
"type" : "Book",
…
"url" : "https://publisher.example.org/mobydick",
…
}
</pre>
</section>
<section id="canonical-identifier">
<h5>Canonical Identifier</h5>
<p>A <a>digital publication's</a>
<dfn>canonical identifier</dfn> property provides a unique identifier for the publication.
It is expressed using the <code>id</code> property.</p>
<table class="zebra">
<thead>
<tr>
<th>Term</th>
<th>Description</th>
<th>Required Value</th>
<th>Value Type</th>
<th>[[!schema.org]] Mapping</th>
</tr>
</thead>
<tbody>
<tr>
<td>
<code data-dfn-for="PublicationManifest">
<dfn>id</dfn>
</code>
</td>
<td>Preferred version of the publication.</td>
<td>A URL record [[!url]].</td>
<td><a href="#value-id">Identifier</a></td>
<td>(None)</td>
</tr>
</tbody>
</table>
<p>The canonical identifier SHOULD be a <a>URL</a> that resolves to the preferred version of the
<a>digital publication</a>. Using a URL provides a measure of permanence above and
beyond a digital publication's <a href="#address">address(es)</a>. If a digital publication
is permanently relocated to a new URL, for example, the canonical address provides a way of
discovering the new location (e.g., a <abbr title="Digital Object Identifier">DOI</abbr>
registry could be updated with the new URL, or a redirect could be added to the URL of the
canonical identifier). It is also intended to provide a means of identifying instances of
the same digital publication hosted at different URLs.</p>
<p class="note">Ensuring uniqueness of canonical identifiers is outside the scope of this
specification. The actual achievable uniqueness depends on such factors as the conventions
of the identifier scheme used and the degree of control over assignment of identifiers.</p>
<p>If a canonical identifier is not provided in the manifest, or the value is an invalid URL,
the digital publication does not have a canonical identifier. User agents MUST NOT attempt
to construct a canonical identifier from any other identifiers provided in the manifest for
the canonical manifest.</p>
<p>The specification of the canonical identifier MAY be complemented by the inclusion of
additional types of identifiers using the <a href="https://schema.org/identifier"
><code>identifier</code> property</a> [[!schema.org]] and/or its subtypes.</p>
<pre class="example" title="Example of setting the canonical identifier and the address as URLs">
{
"@context" : ["https://schema.org","https://www.w3.org/ns/wp-context"],
"type" : "TechArticle",
…
"id" : "http://www.w3.org/TR/tabular-data-model/",
"url" : "http://www.w3.org/TR/2015/REC-tabular-data-model-20151217/",
…
}
</pre>
<pre class="example" title="Example of a URN for the canonical identifier">
{
"@context" : ["https://schema.org","https://www.w3.org/ns/wp-context"],
"type" : "Book",
…
"id" : "urn:isbn:9780123456789",
"url" : "https://publisher.example.org/mobydick",
…
}
</pre>
</section>
<section id="creators">
<h5>Creators</h5>
<p>A <dfn>creator</dfn> is an individual or entity responsible for the creation of the
<a>digital publication</a>.</p>
<p>The following properties are categorized as creators:</p>
<table class="zebra">
<thead>
<tr>