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+
+<body class="h-entry" role="document" id="respecDocument"><div class="head" role="contentinfo" id="respecHeader">
+ <p>
+
+ <a href="http://www.w3.org/"><img width="72" height="48" src="https://www.w3.org/Icons/w3c_home" alt="W3C"></a>
+
+ </p>
+ <h1 class="title p-name" id="title" property="dcterms:title">JSON-LD 1.0</h1>
+
+ <h2 property="bibo:subtitle" id="subtitle">A JSON-based Serialization for Linked Data</h2>
+
+ <h2 property="dcterms:issued" datatype="xsd:dateTime" content="2013-11-05T05:00:00.000Z" id="w3c-proposed-recommendation-05-november-2013"><abbr title="World Wide Web Consortium">W3C</abbr> Proposed Recommendation <time class="dt-published" datetime="2013-11-05">05 November 2013</time></h2>
+ <dl>
+
+ <dt>This version:</dt>
+ <dd><a class="u-url" href="http://www.w3.org/TR/2013/PR-json-ld-20131105/">http://www.w3.org/TR/2013/PR-json-ld-20131105/</a></dd>
+ <dt>Latest published version:</dt>
+ <dd><a href="http://www.w3.org/TR/json-ld/">http://www.w3.org/TR/json-ld/</a></dd>
+
+
+ <dt>Latest editor's draft:</dt>
+ <dd><a href="http://dvcs.w3.org/hg/json-ld/raw-file/default/spec/latest/json-ld/index.html">http://dvcs.w3.org/hg/json-ld/raw-file/default/spec/latest/json-ld/index.html</a></dd>
+
+
+
+
+
+ <dt>Previous version:</dt>
+ <dd><a rel="dcterms:replaces" href="http://www.w3.org/TR/2013/CR-json-ld-20130910/">http://www.w3.org/TR/2013/CR-json-ld-20130910/</a></dd>
+
+
+ <dt>Editors:</dt>
+ <dd class="p-author h-card vcard" rel="bibo:editor" inlist=""><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Manu Sporny" href="http://manu.sporny.org/">Manu Sporny</a>, <a rel="foaf:workplaceHomepage" class="p-org org h-org h-card" href="http://digitalbazaar.com/">Digital Bazaar</a></span>
+</dd>
+<dd class="p-author h-card vcard" rel="bibo:editor" inlist=""><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Gregg Kellogg" href="http://greggkellogg.net/">Gregg Kellogg</a>, <a rel="foaf:workplaceHomepage" class="p-org org h-org h-card" href="http://kellogg-assoc.com/">Kellogg Associates</a></span>
+</dd>
+<dd class="p-author h-card vcard" rel="bibo:editor" inlist=""><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Markus Lanthaler" href="http://www.markus-lanthaler.com/">Markus Lanthaler</a>, <a rel="foaf:workplaceHomepage" class="p-org org h-org h-card" href="http://www.tugraz.at/">Graz University of Technology</a></span>
+</dd>
+
+
+ <dt>Authors:</dt>
+ <dd class="p-author h-card vcard" rel="dcterms:contributor"><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Manu Sporny" href="http://digitalbazaar.com/">Manu Sporny</a>, <a rel="foaf:workplaceHomepage" class="p-org org h-org h-card" href="http://digitalbazaar.com/">Digital Bazaar</a></span>
+</dd>
+<dd class="p-author h-card vcard" rel="dcterms:contributor"><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Dave Longley" href="http://digitalbazaar.com/">Dave Longley</a>, <a rel="foaf:workplaceHomepage" class="p-org org h-org h-card" href="http://digitalbazaar.com/">Digital Bazaar</a></span>
+</dd>
+<dd class="p-author h-card vcard" rel="dcterms:contributor"><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Gregg Kellogg" href="http://greggkellogg.net/">Gregg Kellogg</a>, <a rel="foaf:workplaceHomepage" class="p-org org h-org h-card" href="http://kellogg-assoc.com/">Kellogg Associates</a></span>
+</dd>
+<dd class="p-author h-card vcard" rel="dcterms:contributor"><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Markus Lanthaler" href="http://www.markus-lanthaler.com/">Markus Lanthaler</a>, <a rel="foaf:workplaceHomepage" class="p-org org h-org h-card" href="http://www.tugraz.at/">Graz University of Technology</a></span>
+</dd>
+<dd class="p-author h-card vcard" rel="dcterms:contributor"><span typeof="foaf:Person"><a class="u-url url p-name fn" rel="foaf:homepage" property="foaf:name" content="Niklas Lindström" href="http://neverspace.net/">Niklas Lindström</a></span>
+</dd>
+
+
+
+ </dl>
+
+
+ <p>
+
+ This document is also available in this non-normative format:
+
+ <a rel="alternate" href="diff-20130910.html">diff to previous version</a>
+ </p>
+
+
+
+
+ <p class="copyright">
+ <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> ©
+ 2010-2013
+
+ <a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup>
+ (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>,
+ <a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
+ <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved.
+ <abbr title="World Wide Web Consortium">W3C</abbr> <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
+ <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and
+ <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.
+ </p>
+
+
+ <hr>
+</div>
+<section id="abstract" class="introductory" property="dcterms:abstract" datatype="" typeof="bibo:Chapter" resource="#abstract" rel="bibo:chapter"><h2 aria-level="1" role="heading" id="h2_abstract">Abstract</h2>
+ <p>JSON is a useful data serialization and messaging format.
+ This specification defines JSON-LD, a JSON-based format to serialize
+ Linked Data. The syntax is designed to easily integrate into deployed
+ systems that already use JSON, and provides a smooth upgrade path from
+ JSON to JSON-LD.
+ It is primarily intended to be a way to use Linked Data in Web-based
+ programming environments, to build interoperable Web services, and to
+ store Linked Data in JSON-based storage engines.</p>
+</section><section id="sotd" class="introductory" typeof="bibo:Chapter" resource="#sotd" rel="bibo:chapter"><h2 aria-level="1" role="heading" id="h2_sotd">Status of This Document</h2>
+
+
+
+ <p>
+ <em>This section describes the status of this document at the time of its publication. Other
+ documents may supersede this document. A list of current <abbr title="World Wide Web Consortium">W3C</abbr> publications and the latest revision
+ of this technical report can be found in the <a href="http://www.w3.org/TR/"><abbr title="World Wide Web Consortium">W3C</abbr> technical reports
+ index</a> at http://www.w3.org/TR/.</em>
+ </p>
+
+ <p>This document has been under development for over 30 months in the
+ JSON for Linking Data Community Group. The document has been
+ transferred to the RDF Working Group for review, improvement, and publication.
+ The specification has undergone significant development, review, and changes
+ during the course of the last 30 months.</p>
+
+ <p>There are several independent
+ <a href="http://json-ld.org/test-suite/reports/">interoperable implementations</a> of
+ this specification. There is a fairly complete test suite [<cite><a class="bibref" href="#bib-JSON-LD-TESTS">JSON-LD-TESTS</a></cite>]
+ and a <a href="http://json-ld.org/playground/">live JSON-LD editor</a>
+ that is capable of demonstrating the features described in
+ this document. While development on implementations, the test suite
+ and the live editor will continue, they are believed to be mature enough
+ to be integrated into a non-production system at this point in time with
+ the expectation that they could be used in a production system within the
+ next three months.</p>
+
+ <p>There are a number of ways that one may participate in the development of
+ this specification:</p>
+
+ <ul>
+ <li>If you want to make sure that your feedback is formally addressed by
+ the RDF Working Group, you should send it to public-rdf-comments:
+ <a href="http://lists.w3.org/Archives/Public/public-rdf-comments/">public-rdf-comments@w3.org</a></li>
+
+ <li>Ad-hoc technical discussion primarily occurs on the public community mailing list:
+ <a href="http://lists.w3.org/Archives/Public/public-linked-json/">public-linked-json@w3.org</a></li>
+
+ <li><a href="http://json-ld.org/minutes/">Public JSON-LD Community Group teleconferences</a>
+ are held on Tuesdays at 1500UTC every week.</li>
+
+ <li>RDF Working Group teleconferences are held on Wednesdays at 1500UTC
+ every week. Participation is limited to RDF Working Group members.</li>
+
+ <li>Specification bugs and issues should be reported in the
+ <a href="https://github.com/json-ld/json-ld.org/issues">issue tracker</a>
+ if you do not want to send an e-mail to the public-rdf-comments mailing
+ list.</li>
+
+ <li><a href="https://github.com/json-ld/json-ld.org/tree/master/spec">Source code</a>
+ for the specification can be found on Github.</li>
+
+ <li>The <a href="http://webchat.freenode.net/?channels=json-ld">#json-ld</a>
+ IRC channel is available for real-time discussion on irc.freenode.net.</li>
+ </ul>
+
+ <p>Changes since the
+ <a href="http://www.w3.org/TR/2013/WD-json-ld-20130411/">11 April 2013 Last Call Working Draft</a>:</p>
+
+ <ul>
+ <li>Allow keyword aliases to be defined using expanded term definitions</li>
+ <li>Mention profile URIs also in the sections describing the various document forms</li>
+ <li>Support relative IRIs in <code>@base</code></li>
+ <li>Clarify how the <code>profile</code> media type parameter is used in the content
+ negotiation process</li>
+ <li>Update grammar to disallow blank nodes as data types</li>
+ <li>Update grammar to allow blank node identifiers as value of <code>@vocab</code></li>
+ <li>Align the JSON-LD Data Model with the RDF Data Model</li>
+ <li>Support processing of documents with a <code>+json</code> media type as defined in
+ [<cite><a class="bibref" href="#bib-RFC6839">RFC6839</a></cite>]</li>
+ <li>Added a brief description of the data model to the introduction.</li>
+ <li>Fixed a number of document readability and flow issues related to all
+ of the updates made over the last several months</li>
+ </ul>
+
+ <p>Changes since the
+ <a href="http://www.w3.org/TR/2013/CR-json-ld-20130910/">10 September 2013 Candidate Recommendation</a>:</p>
+
+ <ul>
+ <li>Mention context-sensitivity of <code>@type</code> in
+ <a class="sectionRef sec-ref" href="#specifying-the-type">section 5.4 Specifying the Type</a></li>
+ </ul>
+
+
+ <p>
+ This document was published by the <a href="http://www.w3.org/2011/rdf-wg/">RDF Working Group</a> as a Proposed Recommendation.
+
+ This document is intended to become a <abbr title="World Wide Web Consortium">W3C</abbr> Recommendation.
+
+
+
+
+
+
+ The <abbr title="World Wide Web Consortium">W3C</abbr> Membership and other interested parties are invited
+ to review the document and send comments to
+ <a rel="discussion" href="mailto:public-rdf-comments@w3.org">public-rdf-comments@w3.org</a>
+ (<a href="mailto:public-rdf-comments-request@w3.org?subject=subscribe">subscribe</a>,
+ <a href="http://lists.w3.org/Archives/Public/public-rdf-comments/">archives</a>)
+ through 05 December 2013.
+ Advisory Committee Representatives should consult their
+ <a href="https://www.w3.org/2002/09/wbs/myQuestionnaires">WBS questionnaires</a>.
+ Note that substantive technical comments were expected during the Last Call review period that ended 05 August 2009.
+ </p>
+
+
+
+ <p>
+ Publication as a Proposed Recommendation does not imply endorsement by the <abbr title="World Wide Web Consortium">W3C</abbr> Membership.
+ This is a draft document and may be updated, replaced or obsoleted by other documents at
+ any time. It is inappropriate to cite this document as other than work in progress.
+ </p>
+
+
+ <p>
+
+ This document was produced by a group operating under the
+
+ <a id="sotd_patent" about="" rel="w3p:patentRules" href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 <abbr title="World Wide Web Consortium">W3C</abbr> Patent Policy</a>.
+
+
+
+
+
+ <abbr title="World Wide Web Consortium">W3C</abbr> maintains a <a href="http://www.w3.org/2004/01/pp-impl/46168/status" rel="disclosure">public list of any patent disclosures</a>
+
+ made in connection with the deliverables of the group; that page also includes instructions for
+ disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains
+ <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential Claim(s)</a> must disclose the
+ information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
+ 6 of the <abbr title="World Wide Web Consortium">W3C</abbr> Patent Policy</a>.
+
+
+ </p>
+
+
+
+
+</section><section id="toc"><h2 class="introductory" aria-level="1" role="heading" id="h2_toc">Table of Contents</h2><ul class="toc" role="directory" id="respecContents"><li class="tocline"><a href="#introduction" class="tocxref"><span class="secno">1. </span>Introduction</a><ul class="toc"><li class="tocline"><a href="#how-to-read-this-document" class="tocxref"><span class="secno">1.1 </span>How to Read this Document</a></li></ul></li><li class="tocline"><a href="#design-goals-and-rationale" class="tocxref"><span class="secno">2. </span>Design Goals and Rationale</a></li><li class="tocline"><a href="#terminology" class="tocxref"><span class="secno">3. </span>Terminology</a><ul class="toc"><li class="tocline"><a href="#general-terminology" class="tocxref"><span class="secno">3.1 </span>General Terminology</a></li><li class="tocline"><a href="#data-model-overview" class="tocxref"><span class="secno">3.2 </span>Data Model Overview</a></li><li class="tocline"><a href="#syntax-tokens-and-keywords" class="tocxref"><span class="secno">3.3 </span>Syntax Tokens and Keywords</a></li></ul></li><li class="tocline"><a href="#conformance" class="tocxref"><span class="secno">4. </span>Conformance</a></li><li class="tocline"><a href="#basic-concepts" class="tocxref"><span class="secno">5. </span>Basic Concepts</a><ul class="toc"><li class="tocline"><a href="#the-context" class="tocxref"><span class="secno">5.1 </span>The Context</a></li><li class="tocline"><a href="#iris" class="tocxref"><span class="secno">5.2 </span>IRIs</a></li><li class="tocline"><a href="#node-identifiers" class="tocxref"><span class="secno">5.3 </span>Node Identifiers</a></li><li class="tocline"><a href="#specifying-the-type" class="tocxref"><span class="secno">5.4 </span>Specifying the Type</a></li></ul></li><li class="tocline"><a href="#advanced-concepts" class="tocxref"><span class="secno">6. </span>Advanced Concepts</a><ul class="toc"><li class="tocline"><a href="#base-iri" class="tocxref"><span class="secno">6.1 </span>Base <abbr title="Internationalized Resource Identifier">IRI</abbr></a></li><li class="tocline"><a href="#default-vocabulary" class="tocxref"><span class="secno">6.2 </span>Default Vocabulary</a></li><li class="tocline"><a href="#compact-iris" class="tocxref"><span class="secno">6.3 </span>Compact IRIs</a></li><li class="tocline"><a href="#typed-values" class="tocxref"><span class="secno">6.4 </span>Typed Values</a></li><li class="tocline"><a href="#type-coercion" class="tocxref"><span class="secno">6.5 </span>Type Coercion</a></li><li class="tocline"><a href="#embedding" class="tocxref"><span class="secno">6.6 </span>Embedding</a></li><li class="tocline"><a href="#advanced-context-usage" class="tocxref"><span class="secno">6.7 </span>Advanced Context Usage</a></li><li class="tocline"><a href="#interpreting-json-as-json-ld" class="tocxref"><span class="secno">6.8 </span>Interpreting JSON as JSON-LD</a></li><li class="tocline"><a href="#string-internationalization" class="tocxref"><span class="secno">6.9 </span>String Internationalization</a></li><li class="tocline"><a href="#iri-expansion-within-a-context" class="tocxref"><span class="secno">6.10 </span><abbr title="Internationalized Resource Identifier">IRI</abbr> Expansion within a Context</a></li><li class="tocline"><a href="#sets-and-lists" class="tocxref"><span class="secno">6.11 </span>Sets and Lists</a></li><li class="tocline"><a href="#reverse-properties" class="tocxref"><span class="secno">6.12 </span>Reverse Properties</a></li><li class="tocline"><a href="#named-graphs" class="tocxref"><span class="secno">6.13 </span>Named Graphs</a></li><li class="tocline"><a href="#identifying-blank-nodes" class="tocxref"><span class="secno">6.14 </span>Identifying Blank Nodes</a></li><li class="tocline"><a href="#aliasing-keywords" class="tocxref"><span class="secno">6.15 </span>Aliasing Keywords</a></li><li class="tocline"><a href="#data-indexing" class="tocxref"><span class="secno">6.16 </span>Data Indexing</a></li><li class="tocline"><a href="#expanded-document-form" class="tocxref"><span class="secno">6.17 </span>Expanded Document Form</a></li><li class="tocline"><a href="#compacted-document-form" class="tocxref"><span class="secno">6.18 </span>Compacted Document Form</a></li><li class="tocline"><a href="#flattened-document-form" class="tocxref"><span class="secno">6.19 </span>Flattened Document Form</a></li><li class="tocline"><a href="#embedding-json-ld-in-html-documents" class="tocxref"><span class="secno">6.20 </span>Embedding JSON-LD in HTML Documents</a></li></ul></li><li class="tocline"><a href="#data-model" class="tocxref"><span class="secno">7. </span>Data Model</a></li><li class="tocline"><a href="#json-ld-grammar" class="tocxref"><span class="secno">8. </span>JSON-LD Grammar</a><ul class="toc"><li class="tocline"><a href="#terms" class="tocxref"><span class="secno">8.1 </span>Terms</a></li><li class="tocline"><a href="#node-objects" class="tocxref"><span class="secno">8.2 </span>Node Objects</a></li><li class="tocline"><a href="#value-objects" class="tocxref"><span class="secno">8.3 </span>Value Objects</a></li><li class="tocline"><a href="#lists-and-sets" class="tocxref"><span class="secno">8.4 </span>Lists and Sets</a></li><li class="tocline"><a href="#language-maps" class="tocxref"><span class="secno">8.5 </span>Language Maps</a></li><li class="tocline"><a href="#index-maps" class="tocxref"><span class="secno">8.6 </span>Index Maps</a></li><li class="tocline"><a href="#context-definitions" class="tocxref"><span class="secno">8.7 </span>Context Definitions</a></li></ul></li><li class="tocline"><a href="#relationship-to-rdf" class="tocxref"><span class="secno">9. </span>Relationship to RDF</a><ul class="toc"><li class="tocline"><a href="#serializing-deserializing-rdf" class="tocxref"><span class="secno">9.1 </span>Serializing/Deserializing RDF</a></li></ul></li><li class="tocline"><a href="#relationship-to-other-linked-data-formats" class="tocxref"><span class="secno">A. </span>Relationship to Other Linked Data Formats</a><ul class="toc"><li class="tocline"><a href="#turtle" class="tocxref"><span class="secno">A.1 </span>Turtle</a></li><li class="tocline"><a href="#rdfa" class="tocxref"><span class="secno">A.2 </span>RDFa</a></li><li class="tocline"><a href="#microformats" class="tocxref"><span class="secno">A.3 </span>Microformats</a></li><li class="tocline"><a href="#microdata" class="tocxref"><span class="secno">A.4 </span>Microdata</a></li></ul></li><li class="tocline"><a href="#iana-considerations" class="tocxref"><span class="secno">B. </span>IANA Considerations</a></li><li class="tocline"><a href="#acknowledgements" class="tocxref"><span class="secno">C. </span>Acknowledgements</a></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">D. </span>References</a><ul class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">D.1 </span>Normative references</a></li><li class="tocline"><a href="#informative-references" class="tocxref"><span class="secno">D.2 </span>Informative references</a></li></ul></li></ul></section>
+
+
+
+<section class="informative" id="introduction">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_introduction"><span class="secno">1. </span>Introduction</h2><p><em>This section is non-normative.</em></p>
+
+ <p>Linked Data [<cite><a class="bibref" href="#bib-LINKED-DATA">LINKED-DATA</a></cite>] is a way to create a network of
+ standards-based machine interpretable data across different documents and
+ Web sites. It allows an application to start at one piece of Linked Data,
+ and follow embedded links to other pieces of Linked Data that are hosted on
+ different sites across the Web.</p>
+
+ <p>JSON-LD is a lightweight syntax to serialize Linked Data in
+ JSON [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>]. Its design allows existing JSON to be interpreted as
+ Linked Data with minimal changes. JSON-LD is primarily intended to be a
+ way to use Linked Data in Web-based programming environments, to build
+ interoperable Web services, and to store Linked Data in JSON-based storage engines. Since
+ JSON-LD is 100% compatible with JSON, the large number of JSON parsers and libraries
+ available today can be reused. In addition to all the features JSON provides,
+ JSON-LD introduces:</p>
+
+ <ul>
+ <li>a universal identifier mechanism for <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON objects</a>
+ via the use of <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>,</li>
+ <li>a way to disambiguate keys shared among different JSON documents by mapping
+ them to <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> via a <a class="tref internalDFN" title="context" href="#dfn-context">context</a>,</li>
+ <li>a mechanism in which a value in a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> may refer
+ to a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> on a different site on the Web,</li>
+ <li>the ability to annotate <a class="tref internalDFN" title="string" href="#dfn-string">strings</a> with their language,</li>
+ <li>a way to associate datatypes with values such as dates and times,</li>
+ <li>and a facility to express one or more directed graphs, such as a social
+ network, in a single document.</li>
+ </ul>
+
+ <p>
+ JSON-LD is designed to be usable directly as JSON, with no knowledge of RDF
+ [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>]. It is also designed to be usable as RDF, if desired, for
+ use with other Linked Data technologies like SPARQL. Developers who
+ require any of the facilities listed above or need to serialize an RDF Graph
+ or RDF Dataset in a JSON-based syntax will find JSON-LD of interest. People
+ intending to use JSON-LD with RDF tools will find it can be used as another
+ RDF syntax, like Turtle [<cite><a class="bibref" href="#bib-TURTLE">TURTLE</a></cite>]. Complete details of how JSON-LD relates
+ to RDF are in section <a href="#relationship-to-rdf" class="sec-ref"><span class="secno">9.</span> <span class="sec-title">Relationship to RDF</span></a>.
+ </p>
+
+ <p>
+ The syntax is designed to not disturb already
+ deployed systems running on JSON, but provide a smooth upgrade path from
+ JSON to JSON-LD. Since the shape of such data varies wildly, JSON-LD
+ features mechanisms to reshape documents into a deterministic structure
+ which simplifies their processing.</p>
+
+ <section class="informative" id="how-to-read-this-document">
+ <h3 aria-level="2" role="heading" id="h3_how-to-read-this-document"><span class="secno">1.1 </span>How to Read this Document</h3><p><em>This section is non-normative.</em></p>
+
+ <p>This document is a detailed specification for a serialization of Linked
+ Data in JSON. The document is primarily intended for the following audiences:</p>
+
+ <ul>
+ <li>Software developers who want to encode Linked Data in a variety of
+ programming languages that can use JSON</li>
+ <li>Software developers who want to convert existing JSON to JSON-LD</li>
+ <li>Software developers who want to understand the design decisions and
+ language syntax for JSON-LD</li>
+ <li>Software developers who want to implement processors and APIs for
+ JSON-LD</li>
+ <li>Software developers who want to generate or consume Linked Data,
+ an RDF graph, or an RDF Dataset in a JSON syntax</li>
+ </ul>
+
+ <p>A companion document, the JSON-LD Processing Algorithms and API specification
+ [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>], specifies how to work with JSON-LD at a higher level by
+ providing a standard library interface for common JSON-LD operations.</p>
+
+ <p>To understand the basics in this specification you must first be familiar with
+ JSON, which is detailed in [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>].</p>
+
+ <p>This document almost exclusively uses the term <abbr title="Internationalized Resource Identifier">IRI</abbr>
+ (<a href="http://www.w3.org/TR/ld-glossary/#internationalized-resource-identifier">Internationalized Resource Indicator</a>)
+ when discussing hyperlinks. Many Web developers are more familiar with the
+ URL (<a href="http://www.w3.org/TR/ld-glossary/#uniform-resource-locator">Uniform Resource Locator</a>)
+ terminology. The document also uses, albeit rarely, the URI
+ (<a href="http://www.w3.org/TR/ld-glossary/#uniform-resource-identifier">Uniform Resource Indicator</a>)
+ terminology. While these terms are often used interchangeably among
+ technical communities, they do have important distinctions from one
+ another and the specification goes to great lengths to try and use the
+ proper terminology at all times.
+ </p>
+ </section>
+</section>
+
+<section class="informative" id="design-goals-and-rationale">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_design-goals-and-rationale"><span class="secno">2. </span>Design Goals and Rationale</h2><p><em>This section is non-normative.</em></p>
+
+ <p>JSON-LD satisfies the following design goals:</p>
+
+ <dl>
+ <dt>Simplicity</dt>
+ <dd>No extra processors or software libraries are necessary to use JSON-LD
+ in its most basic form. The language provides developers with a very easy
+ learning curve. Developers only need to know JSON and two
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> (<code>@context</code>
+ and <code>@id</code>) to use the basic functionality in JSON-LD.</dd>
+ <dt>Compatibility</dt>
+ <dd>A JSON-LD document is always a valid JSON document. This ensures that
+ all of the standard JSON libraries work seamlessly with JSON-LD documents.</dd>
+ <dt>Expressiveness</dt>
+ <dd>The syntax serializes directed graphs. This ensures that almost
+ every real world data model can be expressed.</dd>
+ <dt>Terseness</dt>
+ <dd>The JSON-LD syntax is very terse and human readable, requiring as
+ little effort as possible from the developer.</dd>
+ <dt>Zero Edits, most of the time</dt>
+ <dd>JSON-LD ensures a smooth and simple transition from existing
+ JSON-based systems. In many cases,
+ zero edits to the JSON document and the addition of one line to the HTTP response
+ should suffice (see <a class="sectionRef sec-ref" href="#interpreting-json-as-json-ld">section 6.8 Interpreting JSON as JSON-LD</a>).
+ This allows organizations that have
+ already deployed large JSON-based infrastructure to use JSON-LD's features
+ in a way that is not disruptive to their day-to-day operations and is
+ transparent to their current customers. However, there are times where
+ mapping JSON to a graph representation is a complex undertaking.
+ In these instances, rather than extending JSON-LD to support
+ esoteric use cases, we chose not to support the use case. While Zero
+ Edits is a design goal, it is not always possible without adding
+ great complexity to the language. JSON-LD focuses on simplicity when
+ possible.</dd>
+ <dt>Usable as RDF</dt>
+ <dd>JSON-LD is usable by developers as
+ idiomatic JSON, with no need to understand RDF [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].
+ JSON-LD is also usable as RDF, so people intending to use JSON-LD
+ with RDF tools will find it can be used like any other RDF syntax.
+ Complete details of how JSON-LD relates to RDF are in section
+ <a href="#relationship-to-rdf" class="sec-ref"><span class="secno">9.</span> <span class="sec-title">Relationship to RDF</span></a>.</dd>
+ </dl>
+</section>
+
+<section class="normative" id="terminology">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_terminology"><span class="secno">3. </span>Terminology</h2>
+
+ <section class="normative" id="general-terminology">
+ <h3 aria-level="2" role="heading" id="h3_general-terminology"><span class="secno">3.1 </span>General Terminology</h3>
+
+ <p>This document uses the following terms as defined in JSON [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>]. Refer
+ to the <em>JSON Grammar</em> section in [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>] for formal definitions.</p>
+
+ <dl>
+ <dt><dfn title="json-object" id="dfn-json-object">JSON object</dfn></dt><dd>
+ An object structure is represented as a pair of curly brackets surrounding
+ zero or more key-value pairs. A key is a <a class="tref internalDFN" title="string" href="#dfn-string">string</a>.
+ A single colon comes after each key, separating the key from the value.
+ A single comma separates a value from a following key. In contrast to JSON,
+ in JSON-LD the keys in an object must be unique.</dd>
+ <dt><dfn title="array" id="dfn-array">array</dfn></dt>
+ <dd>An array structure is represented as square brackets surrounding zero
+ or more values. Values are separated by commas.
+ In JSON, an array is an <em>ordered</em> sequence of zero or more values.
+ While JSON-LD uses the same array representation as JSON,
+ the collection is <em>unordered</em> by default. While order is
+ preserved in regular JSON arrays, it is not in regular JSON-LD arrays
+ unless specifically defined (see <a class="sectionRef sec-ref" href="#sets-and-lists">section 6.11 Sets and Lists</a>).</dd>
+ <dt><dfn title="string" id="dfn-string">string</dfn></dt><dd>
+ A string is a sequence of zero or more Unicode characters,
+ wrapped in double quotes, using backslash escapes (if necessary).</dd>
+ <dt><dfn title="number" id="dfn-number">number</dfn></dt>
+ <dd>A number is similar to that used in most programming languages, except
+ that the octal and hexadecimal formats are not used and leading zeros
+ are not allowed.</dd>
+ <dt><dfn title="true" id="dfn-true">true</dfn> and <dfn title="false" id="dfn-false">false</dfn></dt><dd>
+ Values that are used to express one of two possible boolean states.</dd>
+ <dt><dfn title="null" id="dfn-null">null</dfn></dt>
+ <dd>The <a class="tref internalDFN" title="null" href="#dfn-null">null</a> value, which is typically used to clear or forget
+ data. For example, a key-value pair in the
+ <code>@context</code> where the value is <a class="tref internalDFN" title="null" href="#dfn-null">null</a> explicitly
+ decouples a <a class="tref internalDFN" title="term" href="#dfn-term">term</a>'s association with an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
+ A key-value pair in the body of a JSON-LD document whose
+ value is <a class="tref internalDFN" title="null" href="#dfn-null">null</a> has the same meaning as if the key-value pair
+ was not defined. If <code>@value</code>, <code>@list</code>, or
+ <code>@set</code> is set to <a class="tref internalDFN" title="null" href="#dfn-null">null</a> in expanded form, then
+ the entire <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> is ignored.</dd>
+ </dl>
+ </section>
+
+ <section class="informative" id="data-model-overview">
+ <h3 aria-level="2" role="heading" id="h3_data-model-overview"><span class="secno">3.2 </span>Data Model Overview</h3><p><em>This section is non-normative.</em></p>
+
+ <p>Generally speaking, the data model used for JSON-LD is a labeled,
+ directed <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a>. The graph contains
+ <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a>, which are connected by
+ <a class="tref internalDFN" title="edge" href="#dfn-edge">edges</a>. A <a class="tref internalDFN" title="node" href="#dfn-node">node</a> is typically data
+ such as a <a class="tref internalDFN" title="string" href="#dfn-string">string</a>, <a class="tref internalDFN" title="number" href="#dfn-number">number</a>,
+ <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed values</a> (like dates and times)
+ or an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
+ There is also a special class of <a class="tref internalDFN" title="node" href="#dfn-node">node</a> called a
+ <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank node</a>, which is typically used to express data that does
+ not have a global identifier like an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
+ <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">Blank nodes</a> are identified using a
+ <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>. This simple data model is incredibly
+ flexible and powerful, capable of modeling almost any kind of
+ data. For a deeper explanation of the data model, see
+ section <a href="#data-model" class="sec-ref"><span class="secno">7.</span> <span class="sec-title">Data Model</span></a>.
+ </p>
+
+ <p>Developers who are familiar with Linked Data technologies will
+ recognize the data model as the RDF Data Model. To dive deeper into how
+ JSON-LD and RDF are related, see
+ section <a href="#relationship-to-rdf" class="sec-ref"><span class="secno">9.</span> <span class="sec-title">Relationship to RDF</span></a>.
+ </p>
+ </section>
+
+ <section class="normative" id="syntax-tokens-and-keywords">
+ <h3 aria-level="2" role="heading" id="h3_syntax-tokens-and-keywords"><span class="secno">3.3 </span>Syntax Tokens and Keywords</h3>
+
+ <p>JSON-LD specifies a number of syntax tokens and <dfn title="keyword" id="dfn-keyword">keywords</dfn>
+ that are a core part of the language:</p>
+
+ <dl>
+ <dt><code>@context</code></dt>
+ <dd>Used to define the short-hand names that are used throughout a JSON-LD
+ document. These short-hand names are called <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> and help
+ developers to express specific identifiers in a compact manner. The
+ <code>@context</code> keyword is described in detail in
+ <a class="sectionRef sec-ref" href="#the-context">section 5.1 The Context</a>.</dd>
+ <dt><code>@id</code></dt>
+ <dd>Used to uniquely identify <em>things</em> that are being described in the document
+ with <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> or
+ <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifiers</a>. This keyword
+ is described in <a class="sectionRef sec-ref" href="#node-identifiers">section 5.3 Node Identifiers</a>.</dd>
+ <dt><code>@value</code></dt>
+ <dd>Used to specify the data that is associated with a particular
+ <a class="tref internalDFN" title="property" href="#dfn-property">property</a> in the graph. This keyword is described in
+ <a class="sectionRef sec-ref" href="#string-internationalization">section 6.9 String Internationalization</a> and
+ <a class="sectionRef sec-ref" href="#typed-values">section 6.4 Typed Values</a>.</dd>
+ <dt><code>@language</code></dt>
+ <dd>Used to specify the language for a particular string value or the default
+ language of a JSON-LD document. This keyword is described in
+ <a class="sectionRef sec-ref" href="#string-internationalization">section 6.9 String Internationalization</a>.</dd>
+ <dt><code>@type</code></dt>
+ <dd>Used to set the data type of a <a class="tref internalDFN" title="node" href="#dfn-node">node</a> or
+ <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed value</a>. This keyword is described in
+ <a class="sectionRef sec-ref" href="#typed-values">section 6.4 Typed Values</a>.</dd>
+ <dt><code>@container</code></dt>
+ <dd>Used to set the default container type for a <a class="tref internalDFN" title="term" href="#dfn-term">term</a>.
+ This keyword is described in <a class="sectionRef sec-ref" href="#sets-and-lists">section 6.11 Sets and Lists</a>.</dd>
+ <dt><code>@list</code></dt>
+ <dd>Used to express an ordered set of data.
+ This keyword is described in <a class="sectionRef sec-ref" href="#sets-and-lists">section 6.11 Sets and Lists</a>.</dd>
+ <dt><code>@set</code></dt>
+ <dd>Used to express an unordered set of data and to ensure that values are always
+ represented as arrays. This keyword is described in
+ <a class="sectionRef sec-ref" href="#sets-and-lists">section 6.11 Sets and Lists</a>.</dd>
+ <dt><code>@reverse</code></dt>
+ <dd>Used to express reverse properties. This keyword is described in
+ <a class="sectionRef sec-ref" href="#reverse-properties">section 6.12 Reverse Properties</a>.</dd>
+ <dt><code>@index</code></dt>
+ <dd>Used to specify that a container is used to index information and
+ that processing should continue deeper into a JSON data structure.
+ This keyword is described in <a class="sectionRef sec-ref" href="#data-indexing">section 6.16 Data Indexing</a>.</dd>
+ <dt><code>@base</code></dt>
+ <dd>Used to set the base <abbr title="Internationalized Resource Identifier">IRI</abbr> against which <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative IRIs</a>
+ are resolved. This keyword is described in <a class="sectionRef sec-ref" href="#base-iri">section 6.1 Base IRI</a>.</dd>
+ <dt><code>@vocab</code></dt>
+ <dd>Used to expand properties and values in <code>@type</code> with a common prefix
+ <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. This keyword is described in <a class="sectionRef sec-ref" href="#default-vocabulary">section 6.2 Default Vocabulary</a>.</dd>
+ <dt><code>@graph</code></dt><dd>Used to express a <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a>.
+ This keyword is described in <a class="sectionRef sec-ref" href="#named-graphs">section 6.13 Named Graphs</a>.</dd>
+ <dt><code>:</code></dt>
+ <dd>The separator for JSON keys and values that use
+ <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact IRIs</a>.</dd>
+ </dl>
+
+ <p>All keys, <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a>, and values in JSON-LD are case-sensitive.</p>
+ </section>
+</section>
+
+<section class="normative" id="conformance">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_conformance"><span class="secno">4. </span>Conformance</h2>
+
+ <p>This specification describes the conformance criteria for JSON-LD documents.
+ This criteria is relevant to authors and authoring tool implementers. As well
+ as sections marked as non-normative, all authoring guidelines, diagrams, examples,
+ and notes in this specification are non-normative. Everything else in this
+ specification is normative.</p>
+
+ <p>A <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a> complies with this specification if it follows
+ the normative statements in appendix <a href="#json-ld-grammar" class="sec-ref"><span class="secno">8.</span> <span class="sec-title">JSON-LD Grammar</span></a>. JSON documents
+ can be interpreted as JSON-LD by following the normative statements in
+ <a class="sectionRef sec-ref" href="#interpreting-json-as-json-ld">section 6.8 Interpreting JSON as JSON-LD</a>. For convenience, normative
+ statements for documents are often phrased as statements on the properties of the document.</p>
+
+ <p>The key words <em class="rfc2119" title="MUST">MUST</em>, <em class="rfc2119" title="MUST NOT">MUST NOT</em>, <em class="rfc2119" title="REQUIRED">REQUIRED</em>, <em class="rfc2119" title="SHALL">SHALL</em>, <em class="rfc2119" title="SHALL NOT">SHALL NOT</em>, <em class="rfc2119" title="SHOULD">SHOULD</em>, <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em>,
+ <em class="rfc2119" title="RECOMMENDED">RECOMMENDED</em>, <em class="rfc2119" title="NOT RECOMMENDED">NOT RECOMMENDED</em>, <em class="rfc2119" title="MAY">MAY</em>, and <em class="rfc2119" title="OPTIONAL">OPTIONAL</em> in this specification have the
+ meaning defined in [<cite><a class="bibref" href="#bib-RFC2119">RFC2119</a></cite>].</p>
+</section>
+
+<section class="informative" id="basic-concepts">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_basic-concepts"><span class="secno">5. </span>Basic Concepts</h2><p><em>This section is non-normative.</em></p>
+
+ <p>JSON [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>] is a lightweight, language-independent data interchange format.
+ It is easy to parse and easy to generate. However, it is difficult to integrate JSON
+ from different sources as the data may contain keys that conflict with other
+ data sources. Furthermore, JSON has no
+ built-in support for hyperlinks, which are a fundamental building block on
+ the Web. Let's start by looking at an example that we will be using for the
+ rest of this section:</p>
+
+ <div class="example"><div class="example-title"><span>Example 1</span>: Sample JSON document</div><pre class="example">{
+ "name": "Manu Sporny",
+ "homepage": "http://manu.sporny.org/",
+ "image": "http://manu.sporny.org/images/manu.png"
+}</pre></div>
+
+ <p>It's obvious to humans that the data is about a person whose
+ <code>name</code> is "Manu Sporny"
+ and that the <code>homepage</code> property contains the URL of that person's homepage.
+ A machine doesn't have such an intuitive understanding and sometimes,
+ even for humans, it is difficult to resolve ambiguities in such representations. This problem
+ can be solved by using unambiguous identifiers to denote the different concepts instead of
+ tokens such as "name", "homepage", etc.</p>
+
+ <p>Linked Data, and the Web in general, uses <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>
+ (Internationalized Resource Identifiers as described in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>]) for unambiguous
+ identification. The idea is to use <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>
+ to assign unambiguous identifiers to data that may be of use to other developers.
+ It is useful for <a class="tref internalDFN" title="term" href="#dfn-term">terms</a>,
+ like <code>name</code> and <code>homepage</code>, to expand to <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>
+ so that developers don't accidentally step on each other's terms. Furthermore, developers and
+ machines are able to use this <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> (by using a web browser, for instance) to go to
+ the term and get a definition of what the term means. This process is known as <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ dereferencing.</p>
+
+ <p>Leveraging the popular <a href="http://schema.org/">schema.org vocabulary</a>,
+ the example above could be unambiguously expressed as follows:</p>
+
+ <div class="example"><div class="example-title"><span>Example 2</span>: Sample JSON-LD document using full IRIs instead of terms</div><pre class="example">{
+ "<span class="highlight">http://schema.org/name</span>": "Manu Sporny",
+ "<span class="highlight">http://schema.org/url</span>": <span class="highlight">{ "@id": </span>"http://manu.sporny.org/" <span class="highlight">}</span>, <span class="comment">← The '@id' keyword means 'This value is an identifier that is an IRI'</span>
+ "<span class="highlight">http://schema.org/image</span>": <span class="highlight">{ "@id": </span>"http://manu.sporny.org/images/manu.png" <span class="highlight">}</span>
+}</pre></div>
+
+ <p>In the example above, every property is unambiguously identified by an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> and all values
+ representing <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> are explicitly marked as such by the
+ <code>@id</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>. While this is a valid JSON-LD
+ document that is very specific about its data, the document is also overly verbose and difficult
+ to work with for human developers. To address this issue, JSON-LD introduces the notion
+ of a <a class="tref internalDFN" title="context" href="#dfn-context">context</a> as described in the next section.</p>
+
+ <section class="informative" id="the-context">
+ <h3 aria-level="2" role="heading" id="h3_the-context"><span class="secno">5.1 </span>The Context</h3><p><em>This section is non-normative.</em></p>
+
+ <p>When two people communicate with one another, the conversation takes
+ place in a shared environment, typically called
+ "the context of the conversation". This shared context allows the
+ individuals to use shortcut terms, like the first name of a mutual friend,
+ to communicate more quickly but without losing accuracy. A context in
+ JSON-LD works in the same way. It allows two applications to use shortcut
+ terms to communicate with one another more efficiently, but without
+ losing accuracy.</p>
+
+ <p>Simply speaking, a <dfn title="context" id="dfn-context">context</dfn> is used to map <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> to
+ <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>. <a class="tref internalDFN" title="term" href="#dfn-term">Terms</a> are case sensitive
+ and any valid <a class="tref internalDFN" title="string" href="#dfn-string">string</a> that is not a reserved JSON-LD <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>
+ can be used as a <a class="tref internalDFN" title="term" href="#dfn-term">term</a>.</p>
+
+ <p>For the sample document in the previous section, a <a class="tref internalDFN" title="context" href="#dfn-context">context</a> would
+ look something like this:</p>
+
+ <div class="example"><div class="example-title"><span>Example 3</span>: Context for the sample document in the previous section</div><pre class="example">{
+ <span class="highlight">"@context":
+ {
+ "name": "http://schema.org/name",</span> <span class="comment">← This means that 'name' is shorthand for 'http://schema.org/name'</span> <span class="highlight">
+ "image": {
+ "@id": "http://schema.org/image",</span> <span class="comment">← This means that 'image' is shorthand for 'http://schema.org/image'</span> <span class="highlight">
+ "@type": "@id"</span> <span class="comment">← This means that a string value associated with 'image' should be interpreted as an identifier that is an IRI</span> <span class="highlight">
+ },
+ "homepage": {
+ "@id": "http://schema.org/url",</span> <span class="comment">← This means that 'homepage' is shorthand for 'http://schema.org/url'</span> <span class="highlight">
+ "@type": "@id"</span> <span class="comment">← This means that a string value associated with 'homepage' should be interpreted as an identifier that is an IRI</span> <span class="highlight">
+ }
+ }</span>
+}</pre></div>
+
+ <p>As the <a class="tref internalDFN" title="context" href="#dfn-context">context</a> above shows, the value of a <dfn title="term-definition" id="dfn-term-definition">term definition</dfn> can
+ either be a simple string, mapping the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> to an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ or a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a>.</p>
+
+ <p>When a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> is associated with a term, it is called
+ an <dfn title="expanded-term-definition" id="dfn-expanded-term-definition">expanded term definition</dfn>. The example above specifies that
+ the values of <code>image</code> and <code>homepage</code>, if they are
+ strings, are to be interpreted as
+ <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>. <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">Expanded term definitions</a>
+ also allow terms to be used for <a href="#data-indexing">index maps</a>
+ and to specify whether <a class="tref internalDFN" title="array" href="#dfn-array">array</a> values are to be
+ interpreted as <a href="#sets-and-lists">sets or lists</a>.
+ <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">Expanded term definitions</a> may
+ be defined using <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute</a> or
+ <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact IRIs</a> as keys, which is
+ mainly used to associate type or language information with an
+ <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute</a> or <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
+
+ <p><a class="tref internalDFN" title="context" href="#dfn-context">Contexts</a> can either be directly embedded
+ into the document or be referenced. Assuming the context document in the previous
+ example can be retrieved at <code>http://json-ld.org/contexts/person.jsonld</code>,
+ it can be referenced by adding a single line and allows a JSON-LD document to
+ be expressed much more concisely as shown in the example below:</p>
+
+ <div class="example"><div class="example-title"><span>Example 4</span>: Referencing a JSON-LD context</div><pre class="example">{
+ <span class="highlight">"@context": "http://json-ld.org/contexts/person.jsonld",</span>
+ "name": "Manu Sporny",
+ "homepage": "http://manu.sporny.org/",
+ "image": "http://manu.sporny.org/images/manu.png"
+}</pre></div>
+
+ <p>The referenced context not only specifies how the terms map to
+ <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> in the Schema.org vocabulary but also
+ specifies that string values associated with
+ the <code>homepage</code> and <code>image</code> property
+ can be interpreted as an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> (<code>"@type": "@id"</code>,
+ see <a class="sectionRef sec-ref" href="#iris">section 5.2 IRIs</a> for more details). This information allows developers
+ to re-use each other's data without having to agree to how their data will interoperate
+ on a site-by-site basis. External JSON-LD context documents may contain extra
+ information located outside of the <code>@context</code> key, such as
+ documentation about the <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> declared in the
+ document. Information contained outside of the <code>@context</code> value
+ is ignored when the document is used as an external JSON-LD context document.</p>
+
+ <p>JSON documents can be interpreted as JSON-LD without having to be modified by
+ referencing a <a class="tref internalDFN" title="context" href="#dfn-context">context</a> via an HTTP Link Header
+ as described in <a class="sectionRef sec-ref" href="#interpreting-json-as-json-ld">section 6.8 Interpreting JSON as JSON-LD</a>. It is also
+ possible to apply a custom context using the JSON-LD API [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>].</p>
+
+ <p>In <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD documents</a>,
+ <a class="tref internalDFN" title="context" href="#dfn-context">contexts</a> may also be specified inline.
+ This has the advantage that documents can be processed even in the
+ absence of a connection to the Web. Ultimately, this is a modeling decision
+ and different use cases may require different handling.</p>
+
+ <div class="example"><div class="example-title"><span>Example 5</span>: In-line context definition</div><pre class="example">{
+ <span class="highlight">"@context":
+ {
+ "name": "http://schema.org/name",
+ "image": {
+ "@id": "http://schema.org/image",
+ "@type": "@id"
+ },
+ "homepage": {
+ "@id": "http://schema.org/url",
+ "@type": "@id"
+ }
+ },</span>
+ "name": "Manu Sporny",
+ "homepage": "http://manu.sporny.org/",
+ "image": "http://manu.sporny.org/images/manu.png"
+}</pre></div>
+
+ <p>This section only covers the most basic features of the JSON-LD
+ Context. More advanced features related to the JSON-LD Context are covered
+ in section <a href="#advanced-concepts" class="sec-ref"><span class="secno">6.</span> <span class="sec-title">Advanced Concepts</span></a>.
+ </p>
+ </section>
+
+<section class="informative" id="iris">
+ <h3 aria-level="2" role="heading" id="h3_iris"><span class="secno">5.2 </span>IRIs</h3><p><em>This section is non-normative.</em></p>
+
+ <p><a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> (Internationalized Resource Identifiers
+ [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>]) are fundamental to Linked Data as that is how most
+ <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a> and <a class="tref internalDFN" title="property" href="#dfn-property">properties</a>
+ are identified. In JSON-LD, IRIs may be represented as an
+ <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>. An
+ <dfn title="absolute-iri" id="dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn> is defined in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>] as containing a
+ <em>scheme</em> along with <em>path</em> and optional <em>query</em> and
+ <em>fragment</em> segments. A <dfn title="relative-iri" id="dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn> is an <abbr title="Internationalized Resource Identifier">IRI</abbr>
+ that is relative to some other <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
+ In JSON-LD all <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative IRIs</a> are resolved
+ relative to the <dfn title="base-iri" id="dfn-base-iri">base <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn>.</p>
+
+ <p>A <a class="tref internalDFN" title="string" href="#dfn-string">string</a> is interpreted as an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> when it is the
+ value of an <code>@id</code> member:</p>
+
+ <div class="example"><div class="example-title"><span>Example 6</span>: Values of @id are interpreted as IRI</div><pre class="example">{
+...
+ "homepage": { "<span class="highlight">@id</span>": "http://example.com/" }
+...
+}</pre></div>
+
+ <p>Values that are interpreted as <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>, can also be
+ expressed as <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative IRIs</a>. For example,
+ assuming that the following document is located at
+ <code>http://example.com/about/</code>, the <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ <code>../</code> would expand to <code>http://example.com/</code> (for more
+ information on where <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative IRIs</a> can be
+ used, please refer to section <a href="#json-ld-grammar" class="sec-ref"><span class="secno">8.</span> <span class="sec-title">JSON-LD Grammar</span></a>).</p>
+
+ <div class="example"><div class="example-title"><span>Example 7</span>: IRIs can be relative</div><pre class="example">{
+...
+ "homepage": { "<span class="highlight">@id</span>": "../" }
+...
+}</pre></div>
+
+ <p><a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">Absolute IRIs</a> can be expressed directly
+ in the key position like so:</p>
+
+ <div class="example"><div class="example-title"><span>Example 8</span>: IRI as a key</div><pre class="example">{
+...
+ "<span class="highlight">http://schema.org/name</span>": "Manu Sporny",
+...
+}</pre></div>
+
+ <p>In the example above, the key <code>http://schema.org/name</code>
+ is interpreted as an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
+
+ <p>Term-to-<abbr title="Internationalized Resource Identifier">IRI</abbr> expansion occurs if the key matches a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> defined
+ within the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 9</span>: Term expansion from context definition</div><pre class="example">{
+ "<span class="highlight">@context</span>":
+ {
+ "<span class="highlight">name</span>": "<span class="highlight">http://schema.org/name</span>"
+ },
+ "<span class="highlight">name</span>": "Manu Sporny",
+ "status": "trollin'"
+}</pre></div>
+
+ <p>JSON keys that do not expand to an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, such as <code>status</code>
+ in the example above, are not Linked Data and thus ignored when processed.</p>
+
+ <p>If type <a class="tref internalDFN" title="coercion" href="#dfn-coercion">coercion</a> rules are specified in the <code>@context</code> for
+ a particular <a class="tref internalDFN" title="term" href="#dfn-term">term</a> or property <abbr title="Internationalized Resource Identifier">IRI</abbr>, an <abbr title="Internationalized Resource Identifier">IRI</abbr> is generated:</p>
+
+ <div class="example"><div class="example-title"><span>Example 10</span>: Type coercion</div><pre class="example">{<span class="highlight">
+ "@context":
+ {
+ ...
+ "homepage":
+ {
+ "@id": "http://schema.org/url",
+ "@type": "@id"
+ }
+ ...
+ }</span>
+...
+ "homepage": "http://manu.sporny.org/",
+...
+}</pre></div>
+
+ <p>In the example above, since the value <code>http://manu.sporny.org/</code>
+ is expressed as a JSON <a class="tref internalDFN" title="string" href="#dfn-string">string</a>, the type <a class="tref internalDFN" title="coercion" href="#dfn-coercion">coercion</a>
+ rules will transform the value into an <abbr title="Internationalized Resource Identifier">IRI</abbr> when processing the data.
+ See <a class="sectionRef sec-ref" href="#type-coercion">section 6.5 Type Coercion</a> for more
+ details about this feature.</p>
+
+ <p>In summary, <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> can be expressed in a variety of
+ different ways in JSON-LD:</p>
+
+ <ol>
+ <li><a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> keys that have a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> mapping in
+ the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a> expand to an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ (only applies outside of the <a class="tref internalDFN" title="context-definition" href="#dfn-context-definition">context definition</a>).</li>
+ <li>An <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> is generated for the <a class="tref internalDFN" title="string" href="#dfn-string">string</a> value specified using
+ <code>@id</code> or <code>@type</code>.</li>
+ <li>An <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> is generated for the <a class="tref internalDFN" title="string" href="#dfn-string">string</a> value of any key for which there
+ are <a class="tref internalDFN" title="coercion" href="#dfn-coercion">coercion</a> rules that contain a <code>@type</code> key that is
+ set to a value of <code>@id</code> or <code>@vocab</code>.</li>
+ </ol>
+
+ <p>This section only covers the most basic features associated with IRIs
+ in JSON-LD. More advanced features related to IRIs are covered in
+ section <a href="#advanced-concepts" class="sec-ref"><span class="secno">6.</span> <span class="sec-title">Advanced Concepts</span></a>.
+ </p>
+
+</section>
+
+<section class="informative" id="node-identifiers">
+ <h3 aria-level="2" role="heading" id="h3_node-identifiers"><span class="secno">5.3 </span>Node Identifiers</h3><p><em>This section is non-normative.</em></p>
+
+ <p>To be able to externally reference <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a>
+ in a <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a>, it is important that
+ <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a> have an identifier. <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>
+ are a fundamental concept of Linked Data, for
+ <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a> to be truly linked, dereferencing the
+ identifier should result in a representation of that <a class="tref internalDFN" title="node" href="#dfn-node">node</a>.
+ This may allow an application to retrieve further information about a
+ <a class="tref internalDFN" title="node" href="#dfn-node">node</a>.</p>
+
+ <p>In JSON-LD, a <a class="tref internalDFN" title="node" href="#dfn-node">node</a> is identified using the <code>@id</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 11</span>: Identifying a node</div><pre class="example">{
+ "@context":
+ {
+ ...
+ "name": "http://schema.org/name"
+ },
+ <span class="highlight">"@id": "http://me.markus-lanthaler.com/"</span>,
+ "name": "Markus Lanthaler",
+ ...
+}</pre></div>
+
+ <p>The example above contains a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> identified by the <abbr title="Internationalized Resource Identifier">IRI</abbr>
+ <code>http://me.markus-lanthaler.com/</code>.</p>
+
+ <p>This section only covers the most basic features associated with
+ node identifiers in JSON-LD. More advanced features related to
+ node identifiers are covered in section <a href="#advanced-concepts" class="sec-ref"><span class="secno">6.</span> <span class="sec-title">Advanced Concepts</span></a>.
+ </p>
+
+</section>
+
+<section class="informative" id="specifying-the-type">
+<h3 aria-level="2" role="heading" id="h3_specifying-the-type"><span class="secno">5.4 </span>Specifying the Type</h3><p><em>This section is non-normative.</em></p>
+
+<p>The type of a particular node can be specified using the <code>@type</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>. In Linked Data, types are uniquely
+ identified with an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
+
+<div class="example"><div class="example-title"><span>Example 12</span>: Specifying the type for a node</div><pre class="example">{
+...
+ "@id": "http://example.org/places#BrewEats",
+ "<span class="highlight">@type</span>": "<span class="highlight">http://schema.org/Restaurant</span>",
+...
+}</pre></div>
+
+<p>A node can be assigned more than one type by using an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>:</p>
+
+<div class="example"><div class="example-title"><span>Example 13</span>: Specifying multiple types for a node</div><pre class="example">{
+...
+ "@id": "http://example.org/places#BrewEats",
+ "<span class="highlight">@type</span>": <span class="highlight">[ "http://schema.org/Restaurant", "http://schema.org/Brewery" ],</span>
+...
+}</pre></div>
+
+<p>The value of a <code>@type</code> key may also be a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> defined in the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>:</p>
+<div class="example"><div class="example-title"><span>Example 14</span>: Using a term to specify the type</div><pre class="example">{
+ "@context": {
+ ...
+ <span class="highlight">"Restaurant": "http://schema.org/Restaurant", </span>
+ <span class="highlight">"Brewery": "http://schema.org/Brewery"</span>
+ }
+ "@id": "http://example.org/places#BrewEats",
+ <span class="highlight">"@type": [ "Restaurant", "Brewery" ]</span>,
+ ...
+}</pre></div>
+
+<div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_1"><span>Note</span></div><p class="">This section only covers the most basic features associated with
+ types in JSON-LD. It is worth noting that the <code>@type</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> is not only used to specify the type of a
+ <a class="tref internalDFN" title="node" href="#dfn-node">node</a> but also to express <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed values</a>
+ (as described in <a class="sectionRef sec-ref" href="#typed-values">section 6.4 Typed Values</a>) and to
+ <a class="tref internalDFN" title="coercion" href="#dfn-coercion">type coerce</a> values (as described in
+ <a class="sectionRef sec-ref" href="#type-coercion">section 6.5 Type Coercion</a>). Specifically, <code>@type</code>
+ cannot be used in a <a class="tref internalDFN" title="context" href="#dfn-context">context</a> to define a <a class="tref internalDFN" title="node" href="#dfn-node">node's</a>
+ type. For a detailed description of the differences, please refer to
+ <a class="sectionRef sec-ref" href="#typed-values">section 6.4 Typed Values</a>.</p></div>
+
+</section>
+</section>
+
+<section class="normative" id="advanced-concepts">
+<!--OddPage--><h2 aria-level="1" role="heading" id="h2_advanced-concepts"><span class="secno">6. </span>Advanced Concepts</h2>
+
+<p>JSON-LD has a number of features that provide functionality above and beyond
+ the core functionality described above. The following section describes this
+ advanced functionality in more detail.</p>
+
+<section class="informative" id="base-iri">
+ <h3 aria-level="2" role="heading" id="h3_base-iri"><span class="secno">6.1 </span>Base <abbr title="Internationalized Resource Identifier">IRI</abbr></h3><p><em>This section is non-normative.</em></p>
+
+ <p>JSON-LD allows <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>s to be specified in a relative form which is
+ resolved against the document base according
+ <cite><a href="http://tools.ietf.org/html/rfc3986#section-5.1">section 5.1 Establishing a Base URI</a></cite>
+ of [<cite><a class="bibref" href="#bib-RFC3986">RFC3986</a></cite>]. The base <abbr title="Internationalized Resource Identifier">IRI</abbr> may be explicitly set with a <a class="tref internalDFN" title="context" href="#dfn-context">context</a>
+ using the <code>@base</code> keyword.</p>
+
+ <p>For example, if a JSON-LD document was retrieved from <code>http://example.com/document.jsonld</code>,
+ relative IRIs would resolve against that <abbr title="Internationalized Resource Identifier">IRI</abbr>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 15</span>: Use a relative IRI as node identifier</div><pre class="example">{
+ "@context": {
+ "label": "http://www.w3.org/2000/01/rdf-schema#label"
+ },
+ <span class="highlight">"@id": ""</span>,
+ "label": "Just a simple document"
+}</pre></div>
+
+ <p>This document uses an empty <code>@id</code>, which resolves to the document base.
+ However, if the document is moved to a different location, the <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> would change.
+ To prevent this without having to use an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="context" href="#dfn-context">context</a>
+ may define a <code>@base</code> mapping, to overwrite the base <abbr title="Internationalized Resource Identifier">IRI</abbr> for the document.</p>
+
+ <div class="example"><div class="example-title"><span>Example 16</span>: Setting the document base in a document</div><pre class="example">{
+ "@context": {
+ <span class="highlight">"@base": "http://example.com/document.jsonld"</span>
+ },
+ "@id": "",
+ "label": "Just a simple document"
+}</pre></div>
+
+ <p>Setting <code>@base</code> to <a class="tref internalDFN" title="null" href="#dfn-null">null</a> will prevent
+ <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative IRIs</a> to be expanded to
+ <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute IRIs</a>.</p>
+
+ <p>Please note that the <code>@base</code> will be ignored if used in
+ external contexts.</p>
+</section>
+
+<section class="informative" id="default-vocabulary">
+ <h3 aria-level="2" role="heading" id="h3_default-vocabulary"><span class="secno">6.2 </span>Default Vocabulary</h3><p><em>This section is non-normative.</em></p>
+
+ <p>At times, all properties and types may come from the same vocabulary. JSON-LD's
+ <code>@vocab</code> keyword allows an author to set a common prefix to be used
+ for all properties and types that do not match a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> and are neither
+ a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> nor an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (i.e., they do
+ not contain a colon).</p>
+
+ <div class="example"><div class="example-title"><span>Example 17</span>: Using a common vocabulary prefix</div><pre class="example">{
+ "@context": {
+ <span class="highlight">"@vocab": "http://schema.org/"</span>
+ }
+ "@id": "http://example.org/places#BrewEats",
+ "@type": <span class="highlight">"Restaurant"</span>,
+ <span class="highlight">"name"</span>: "Brew Eats"
+ ...
+}</pre></div>
+
+ <p>If <code>@vocab</code> is used but certain keys in an
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">object</a> should not be expanded using
+ the vocabulary <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> can be explicitly set
+ to <a class="tref internalDFN" title="null" href="#dfn-null">null</a> in the <a class="tref internalDFN" title="context" href="#dfn-context">context</a>. For instance, in the
+ example below the <code>databaseId</code> member would not expand to an
+ <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
+
+ <div class="example"><div class="example-title"><span>Example 18</span>: Using the null keyword to ignore data</div><pre class="example">{
+ "@context":
+ {
+ "@vocab": "http://schema.org/",
+ <span class="highlight">"databaseId": null</span>
+ },
+ "@id": "http://example.org/places#BrewEats",
+ "@type": "Restaurant",
+ "name": "Brew Eats",
+ <span class="highlight">"databaseId"</span>: "23987520"
+}</pre></div>
+</section>
+
+<section class="informative" id="compact-iris">
+ <h3 aria-level="2" role="heading" id="h3_compact-iris"><span class="secno">6.3 </span>Compact IRIs</h3><p><em>This section is non-normative.</em></p>
+
+ <p>A <dfn title="compact-iri" id="dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn> is a way of expressing an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ using a <em>prefix</em> and <em>suffix</em> separated by a colon (<code>:</code>).
+ The <dfn title="prefix" id="dfn-prefix">prefix</dfn> is a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> taken from the
+ <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a> and is a short string identifying a
+ particular <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> in a JSON-LD document. For example, the
+ prefix <code>foaf</code> may be used as a short hand for the
+ Friend-of-a-Friend vocabulary, which is identified using the <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ <code>http://xmlns.com/foaf/0.1/</code>. A developer may append
+ any of the FOAF vocabulary terms to the end of the prefix to specify a short-hand
+ version of the <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> for the vocabulary term. For example,
+ <code>foaf:name</code> would be expanded to the <abbr title="Internationalized Resource Identifier">IRI</abbr>
+ <code>http://xmlns.com/foaf/0.1/name</code>.</p>
+
+ <div class="example"><div class="example-title"><span>Example 19</span>: Prefix expansion</div><pre class="example">{
+ "<span class="highlight">@context</span>":
+ {
+ "<span class="highlight">foaf</span>": "<span class="highlight">http://xmlns.com/foaf/0.1/</span>"
+...
+ },
+ "@type": "<span class="highlight">foaf:Person</span>"
+ "<span class="highlight">foaf:name</span>": "Dave Longley",
+...
+}</pre></div>
+
+ <p>In the example above, <code>foaf:name</code> expands to the <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ <code>http://xmlns.com/foaf/0.1/name</code> and <code>foaf:Person</code> expands
+ to <code>http://xmlns.com/foaf/0.1/Person</code>.</p>
+
+ <p><a class="tref internalDFN" title="prefix" href="#dfn-prefix">Prefixes</a> are expanded when the form of the value
+ is a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> represented as a <code>prefix:suffix</code>
+ combination, the <em>prefix</em> matches a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> defined within the
+ <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>, and the <em>suffix</em> does not begin with two
+ slashes (<code>//</code>). The <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is expanded by
+ concatenating the <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> mapped to the <em>prefix</em> to the (possibly empty)
+ <em>suffix</em>. If the <em>prefix</em> is not defined in the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>,
+ or the suffix begins with two slashes (such as in <code>http://example.com</code>),
+ the value is interpreted as <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> instead. If the prefix is an
+ underscore (<code>_</code>), the value is interpreted as <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>
+ instead.</p>
+
+
+ <p>It's also possible to use compact IRIs within the context as shown in the
+ following example:</p>
+
+ <div class="example"><div class="example-title"><span>Example 20</span>: Using vocabularies</div><pre class="example">{
+ "@context":
+ {
+ "xsd": "http://www.w3.org/2001/XMLSchema#",
+ <span class="highlight">"foaf": "http://xmlns.com/foaf/0.1/"</span>,
+ <span class="highlight">"foaf:homepage"</span>: { "@type": "@id" },
+ "picture": { "@id": <span class="highlight">"foaf:depiction"</span>, "@type": "@id" }
+ },
+ "@id": "http://me.markus-lanthaler.com/",
+ "@type": "foaf:Person",
+ "foaf:name": "Markus Lanthaler",
+ "foaf:homepage": "http://www.markus-lanthaler.com/",
+ "picture": "http://twitter.com/account/profile_image/markuslanthaler"
+}</pre></div>
+</section>
+
+<section class="informative" id="typed-values">
+<h3 aria-level="2" role="heading" id="h3_typed-values"><span class="secno">6.4 </span>Typed Values</h3><p><em>This section is non-normative.</em></p>
+
+<p>
+ A value with an associated type, also known as a
+ <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed value</a>, is indicated by associating a value with
+ an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> which indicates the value's type. Typed values may be
+ expressed in JSON-LD in three ways:
+</p>
+
+<ol>
+ <li>By utilizing the <code>@type</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> when defining
+ a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> within a <code>@context</code> section.</li>
+ <li>By utilizing a <a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a>.</li>
+ <li>By using a native JSON type such as <a class="tref internalDFN" title="number" href="#dfn-number">number</a>, <a class="tref internalDFN" title="true" href="#dfn-true">true</a>, or <a class="tref internalDFN" title="false" href="#dfn-false">false</a>.</li>
+</ol>
+
+<p>The first example uses the <code>@type</code> keyword to associate a
+type with a particular <a class="tref internalDFN" title="term" href="#dfn-term">term</a> in the <code>@context</code>:</p>
+
+<div class="example"><div class="example-title"><span>Example 21</span>: Expanded term definition with type coercion</div><pre class="example">{
+ <span class="highlight">"@context":
+ {
+ "modified":
+ {
+ "@id": "http://purl.org/dc/terms/modified",
+ "@type": "http://www.w3.org/2001/XMLSchema#dateTime"
+ }
+ },</span>
+...
+ "@id": "http://example.com/docs/1",
+ "modified": "2010-05-29T14:17:39+02:00",
+...
+}</pre></div>
+
+<p>The <em>modified</em> key's value above is automatically type coerced to a
+ <em>dateTime</em> value because of the information specified in the
+ <code>@context</code>. A JSON-LD processor will interpret the example above
+ as follows:</p>
+
+<table class="example">
+<thead>
+ <tr><th>Subject</th>
+ <th>Property</th>
+ <th>Value</th>
+ <th>Value Type</th>
+</tr></thead>
+<tbody>
+<tr>
+ <td>http://example.com/docs/1</td>
+ <td>http://purl.org/dc/terms/modified</td>
+ <td>2010-05-29T14:17:39+02:00</td>
+ <td>http://www.w3.org/2001/XMLSchema#dateTime</td>
+</tr>
+</tbody>
+</table>
+
+<p>The second example uses the expanded form of setting the type information
+in the body of a JSON-LD document:</p>
+
+<div class="example"><div class="example-title"><span>Example 22</span>: Expanded value with type</div><pre class="example">{
+ "@context":
+ {
+ "modified":
+ {
+ "@id": "http://purl.org/dc/terms/modified"
+ }
+ },
+...
+ "modified":
+ <span class="highlight">{
+ "@value": "2010-05-29T14:17:39+02:00",
+ "@type": "http://www.w3.org/2001/XMLSchema#dateTime"
+ }</span>
+...
+}</pre></div>
+
+<p>Both examples above would generate the value
+ <code>2010-05-29T14:17:39+02:00</code> with the type
+ <code>http://www.w3.org/2001/XMLSchema#dateTime</code>. Note that it is
+ also possible to use a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> or a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> to
+ express the value of a type.</p>
+
+<div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_2"><span>Note</span></div><p class="">The <code>@type</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> is also used to associate a type
+ with a <a class="tref internalDFN" title="node" href="#dfn-node">node</a>. The concept of a <a class="tref internalDFN" title="node-type" href="#dfn-node-type">node type</a> and
+ a <a class="tref internalDFN" title="value-type" href="#dfn-value-type">value type</a> are different.</p></div>
+
+<p>Generally speaking, a <dfn title="node-type" id="dfn-node-type">node type</dfn> specifies the type of thing
+ that is being described, like a person, place, event, or web page. A
+ <dfn title="value-type" id="dfn-value-type">value type</dfn> specifies the data type of a particular value, such
+ as an integer, a floating point number, or a date.</p>
+
+<div class="example"><div class="example-title"><span>Example 23</span>: Example demonstrating the context-sensitivity for @type</div><pre class="example">{
+...
+ "@id": "http://example.org/posts#TripToWestVirginia",
+ <span class="highlight">"@type": "http://schema.org/BlogPosting"</span>, <span class="comment">← This is a node type</span>
+ "modified":
+ {
+ "@value": "2010-05-29T14:17:39+02:00",
+ <span class="highlight">"@type": "http://www.w3.org/2001/XMLSchema#dateTime"</span> <span class="comment">← This is a value type</span>
+ }
+...
+}</pre></div>
+
+<p>The first use of <code>@type</code> associates a <a class="tref internalDFN" title="node-type" href="#dfn-node-type">node type</a>
+ (<code>http://schema.org/BlogPosting</code>) with the <a class="tref internalDFN" title="node" href="#dfn-node">node</a>,
+ which is expressed using the <code>@id</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>.
+ The second use of <code>@type</code> associates a <a class="tref internalDFN" title="value-type" href="#dfn-value-type">value type</a>
+ (<code>http://www.w3.org/2001/XMLSchema#dateTime</code>) with the
+ value expressed using the <code>@value</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>. As a
+ general rule, when <code>@value</code> and <code>@type</code> are used in
+ the same <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a>, the <code>@type</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> is expressing a <a class="tref internalDFN" title="value-type" href="#dfn-value-type">value type</a>.
+ Otherwise, the <code>@type</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> is expressing a
+ <a class="tref internalDFN" title="node-type" href="#dfn-node-type">node type</a>. The example above expresses the following data:</p>
+
+<table class="example">
+<thead>
+ <tr><th>Subject</th>
+ <th>Property</th>
+ <th>Value</th>
+ <th>Value Type</th>
+</tr></thead>
+<tbody>
+<tr>
+ <td>http://example.org/posts#TripToWestVirginia</td>
+ <td>http://www.w3.org/1999/02/22-rdf-syntax-ns#type</td>
+ <td>http://schema.org/BlogPosting</td>
+ <td style="text-align:center;">-</td>
+</tr>
+<tr>
+ <td>http://example.org/posts#TripToWestVirginia</td>
+ <td>http://purl.org/dc/terms/modified</td>
+ <td>2010-05-29T14:17:39+02:00</td>
+ <td>http://www.w3.org/2001/XMLSchema#dateTime</td>
+</tr>
+</tbody>
+</table>
+
+</section>
+
+<section class="informative" id="type-coercion">
+<h3 aria-level="2" role="heading" id="h3_type-coercion"><span class="secno">6.5 </span>Type Coercion</h3><p><em>This section is non-normative.</em></p>
+
+<p>JSON-LD supports the coercion of values to particular data types.
+Type <dfn title="coercion" id="dfn-coercion">coercion</dfn> allows someone deploying JSON-LD to coerce the incoming or
+outgoing values to the proper data type based on a mapping of data type <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> to
+<a class="tref internalDFN" title="term" href="#dfn-term">terms</a>. Using type coercion, value representation is preserved without requiring
+the data type to be specified with each piece of data.</p>
+
+<p>Type coercion is specified within an <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a>
+ using the <code>@type</code> key. The value of this key expands to an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
+ Alternatively, the <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> <code>@id</code> or <code>@vocab</code> may be used
+ as value to indicate that within the body of a JSON-LD document, a <a class="tref internalDFN" title="string" href="#dfn-string">string</a> value of a
+ <a class="tref internalDFN" title="term" href="#dfn-term">term</a> coerced to <code>@id</code> or <code>@vocab</code> is to be interpreted as an
+ <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. The difference between <code>@id</code> and <code>@vocab</code> is how values are expanded
+ to <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute IRIs</a>. <code>@vocab</code> first tries to expand the value
+ by interpreting it as <a class="tref internalDFN" title="term" href="#dfn-term">term</a>. If no matching <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is found in the
+ <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>, it tries to expand it as <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ if there's a colon in the value; otherwise, it will expand the value using the
+ <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context's</a> vocabulary mapping, if present, or by interpreting it
+ as <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>. Values coerced to <code>@id</code> in contrast are expanded as
+ <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> if a colon is present; otherwise, they are interpreted
+ as <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
+
+<p><a class="tref internalDFN" title="term" href="#dfn-term">Terms</a> or <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact IRIs</a> used as the value of a
+ <code>@type</code> key may be defined within the same context. This means that one may specify a
+ <a class="tref internalDFN" title="term" href="#dfn-term">term</a> like <code>xsd</code> and then use <code>xsd:integer</code> within the same
+ context definition.</p>
+
+<p>The example below demonstrates how a JSON-LD author can coerce values to
+<a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed values</a> and <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>.</p>
+
+<div class="example"><div class="example-title"><span>Example 24</span>: Expanded term definition with types</div><pre class="example">{
+ "@context":
+ {
+ "xsd": "http://www.w3.org/2001/XMLSchema#",
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "age":
+ <span class="highlight">{
+ "@id": "http://xmlns.com/foaf/0.1/age",
+ "@type": "xsd:integer"
+ }</span>,
+ "homepage":
+ <span class="highlight">{
+ "@id": "http://xmlns.com/foaf/0.1/homepage",
+ "@type": "@id"
+ }</span>
+ },
+ "@id": "http://example.com/people#john",
+ "name": "John Smith",
+ "age": <span class="highlight">"41"</span>,
+ "homepage":
+ <span class="highlight">[
+ "http://personal.example.org/",
+ "http://work.example.com/jsmith/"
+ ]</span>
+}</pre></div>
+
+<p>The example shown above would generate the following data.</p>
+
+<table class="example">
+<thead>
+ <tr><th>Subject</th>
+ <th>Property</th>
+ <th>Value</th>
+ <th>Value Type</th>
+</tr></thead>
+<tbody>
+<tr>
+ <td>http://example.com/people#john</td>
+ <td>http://xmlns.com/foaf/0.1/name</td>
+ <td>John Smith</td>
+ <td> </td>
+</tr>
+<tr>
+ <td>http://example.com/people#john</td>
+ <td>http://xmlns.com/foaf/0.1/age</td>
+ <td>41</td>
+ <td>http://www.w3.org/2001/XMLSchema#integer</td>
+</tr>
+<tr>
+ <td rowspan="2">http://example.com/people#john</td>
+ <td rowspan="2">http://xmlns.com/foaf/0.1/homepage</td>
+ <td>http://personal.example.org/</td>
+ <td><a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a></td>
+</tr>
+<tr>
+ <td>http://work.example.com/jsmith/</td>
+ <td><a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a></td>
+</tr>
+</tbody>
+</table>
+
+<p>Terms may also be defined using <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute IRIs</a>
+ or <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact IRIs</a>. This allows coercion rules
+ to be applied to keys which are not represented as a simple <a class="tref internalDFN" title="term" href="#dfn-term">term</a>.
+ For example:</p>
+
+<div class="example"><div class="example-title"><span>Example 25</span>: Term definitions using compact and absolute IRIs</div><pre class="example">{
+ "@context":
+ {
+ "foaf": "http://xmlns.com/foaf/0.1/",
+ "<span class="highlight">foaf:age</span>":
+ {
+ <span class="highlight">"@id": "http://xmlns.com/foaf/0.1/age"</span>,
+ "@type": "xsd:integer"
+ },
+ "<span class="highlight">http://xmlns.com/foaf/0.1/homepage</span>":
+ {
+ "@type": "@id"
+ }
+ },
+ "foaf:name": "John Smith",
+ "<span class="highlight">foaf:age</span>": "41",
+ "<span class="highlight">http://xmlns.com/foaf/0.1/homepage</span>":
+ [
+ "http://personal.example.org/",
+ "http://work.example.com/jsmith/"
+ ]
+}</pre></div>
+
+<p>In this case the <code>@id</code> definition in the term definition is optional.
+ If it does exist, the <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> representing
+ the term will always be expanded to <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> defined by the <code>@id</code>
+ key—regardless of whether a prefix is defined or not.</p>
+
+<p>Type coercion is always performed using the unexpanded value of the key. In the
+ example above, that means that type coercion is done looking for <code>foaf:age</code>
+ in the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a> and not for the corresponding, expanded
+ <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> <code>http://xmlns.com/foaf/0.1/age</code>.</p>
+
+<div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_3"><span>Note</span></div><p class="">Keys in the context are treated as <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> for the purpose of
+ expansion and value coercion. At times, this may result in multiple representations for the same expanded <abbr title="Internationalized Resource Identifier">IRI</abbr>.
+ For example, one could specify that <code>dog</code> and <code>cat</code> both expanded to <code>http://example.com/vocab#animal</code>.
+ Doing this could be useful for establishing different type coercion or language specification rules. It also allows a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (or even an
+ absolute <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>) to be defined as something else entirely. For example, one could specify that
+ the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> <code>http://example.org/zoo</code> should expand to
+ <code>http://example.org/river</code>, but this usage is discouraged because it would lead to a
+ great deal of confusion among developers attempting to understand the JSON-LD document.</p></div>
+
+
+</section>
+
+<section class="informative" id="embedding">
+ <h3 aria-level="2" role="heading" id="h3_embedding"><span class="secno">6.6 </span>Embedding</h3><p><em>This section is non-normative.</em></p>
+
+ <p><dfn title="embedding" id="dfn-embedding">Embedding</dfn> is a JSON-LD feature that allows an author to
+ use <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a> as
+ <a class="tref internalDFN" title="property" href="#dfn-property">property</a> values. This is a commonly used mechanism for
+ creating a parent-child relationship between two <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a>.</p>
+
+ <p>The example shows two nodes related by a property from the first node:</p>
+
+ <div class="example"><div class="example-title"><span>Example 26</span>: Embedding a node object as property value of another node object</div><pre class="example">{
+...
+ "name": "Manu Sporny",
+ "<span class="highlight">knows</span>":
+ {
+ "<span class="highlight">@type</span>": "<span class="highlight">Person</span>",
+ "<span class="highlight">name</span>": "<span class="highlight">Gregg Kellogg</span>",
+ }
+...
+}</pre></div>
+
+ <p>
+ A <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>, like the one used above, may be used in
+ any value position in the body of a JSON-LD document.</p>
+</section>
+
+<section class="informative" id="advanced-context-usage">
+ <h3 aria-level="2" role="heading" id="h3_advanced-context-usage"><span class="secno">6.7 </span>Advanced Context Usage</h3><p><em>This section is non-normative.</em></p>
+
+ <p>Section <a href="#the-context" class="sec-ref"><span class="secno">5.1</span> <span class="sec-title">The Context</span></a> introduced the basics of what makes
+ JSON-LD work. This section expands on the basic principles of the
+ <a class="tref internalDFN" title="context" href="#dfn-context">context</a> and demonstrates how more advanced use cases can
+ be achieved using JSON-LD. </p>
+
+ <p>In general, contexts may be used at any time a
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> is defined. The only time that one cannot
+ express a context is inside a context definition itself. For example, a
+ <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a> may use more than one context at different
+ points in a document:</p>
+
+ <div class="example"><div class="example-title"><span>Example 27</span>: Using multiple contexts</div><pre class="example">[
+ {
+ <span class="highlight">"@context": "http://example.org/contexts/person.jsonld",</span>
+ "name": "Manu Sporny",
+ "homepage": "http://manu.sporny.org/",
+ "depiction": "http://twitter.com/account/profile_image/manusporny"
+ },
+ {
+ <span class="highlight">"@context": "http://example.org/contexts/place.jsonld",</span>
+ "name": "The Empire State Building",
+ "description": "The Empire State Building is a 102-story landmark in New York City.",
+ "geo": {
+ "latitude": "40.75",
+ "longitude": "73.98"
+ }
+ }
+]</pre></div>
+
+ <p>Duplicate context <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> are overridden using a
+ most-recently-defined-wins mechanism.</p>
+
+ <div class="example"><div class="example-title"><span>Example 28</span>: Scoped contexts within node objects</div><pre class="example">{
+ <span class="highlight">"@context":
+ {
+ "name": "http://example.com/person#name,
+ "details": "http://example.com/person#details"
+ }"</span>,
+ "<span class="highlight">name</span>": "Markus Lanthaler",
+ ...
+ "details":
+ {
+ <span class="highlight">"@context":
+ {
+ "name": "http://example.com/organization#name"
+ }</span>,
+ "<span class="highlight">name</span>": "Graz University of Technology"
+ }
+}</pre></div>
+
+ <p>In the example above, the <code>name</code> <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is overridden
+ in the more deeply nested <code>details</code> structure. Note that this is
+ rarely a good authoring practice and is typically used when working with
+ legacy applications that depend on a specific structure of the
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a>. If a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is redefined within a
+ context, all previous rules associated with the previous definition are
+ removed. If a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is redefined to <code>null</code>,
+ the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is effectively removed from the list of
+ <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> defined in the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>.</p>
+
+ <p>Multiple contexts may be combined using an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>, which is processed
+ in order. The set of contexts defined within a specific <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> are
+ referred to as <dfn title="local-context" id="dfn-local-context">local contexts</dfn>. The
+ <dfn title="active-context" id="dfn-active-context">active context</dfn> refers to the accumulation of
+ <a class="tref internalDFN" title="local-context" href="#dfn-local-context">local contexts</a> that are in scope at a
+ specific point within the document. Setting a <a class="tref internalDFN" title="local-context" href="#dfn-local-context">local context</a>
+ to <code>null</code> effectively resets the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>
+ to an empty context. The following example specifies an external context
+ and then layers an embedded context on top of the external context:</p>
+
+ <div class="example"><div class="example-title"><span>Example 29</span>: Combining external and local contexts</div><pre class="example">{
+ <span class="highlight">"@context": [
+ "http://json-ld.org/contexts/person.jsonld",
+ {
+ "pic": "http://xmlns.com/foaf/0.1/depiction"
+ }
+ ],</span>
+ "name": "Manu Sporny",
+ "homepage": "http://manu.sporny.org/",
+ <span class="highlight">"pic": "http://twitter.com/account/profile_image/manusporny"</span>
+}</pre></div>
+
+ <div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_4"><span>Note</span></div><p class="">When possible, the <a class="tref internalDFN" title="context" href="#dfn-context">context</a> definition should be put
+ at the top of a JSON-LD document. This makes the document easier to read and
+ might make streaming parsers more efficient. Documents that do not have the
+ <a class="tref internalDFN" title="context" href="#dfn-context">context</a> at the top are still conformant JSON-LD.</p></div>
+
+ <div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_5"><span>Note</span></div><p class="">To avoid forward-compatibility issues, <a class="tref internalDFN" title="term" href="#dfn-term">terms</a>
+ starting with an <code>@</code> character are to be avoided as they
+ might be used as <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> in future versions
+ of JSON-LD. Terms starting with an <code>@</code> character that are not
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">JSON-LD 1.0 keywords</a> are treated as any other term, i.e.,
+ they are ignored unless mapped to an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. Furthermore, the use of
+ empty <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> (<code>""</code>) is not allowed as
+ not all programming languages are able to handle empty JSON keys.</p></div>
+</section>
+
+<section class="normative" id="interpreting-json-as-json-ld">
+ <h3 aria-level="2" role="heading" id="h3_interpreting-json-as-json-ld"><span class="secno">6.8 </span>Interpreting JSON as JSON-LD</h3>
+
+ <p>Ordinary JSON documents can be interpreted as JSON-LD by referencing a JSON-LD
+ <a class="tref internalDFN" title="context" href="#dfn-context">context</a> document in an HTTP Link Header. Doing so allows JSON to
+ be unambiguously machine-readable without requiring developers to drastically
+ change their documents and provides an upgrade path for existing infrastructure
+ without breaking existing clients that rely on the <code>application/json</code>
+ media type or a media type with a <code>+json</code> suffix as defined in
+ [<cite><a class="bibref" href="#bib-RFC6839">RFC6839</a></cite>].</p>
+
+ <p>In order to use an external context with an ordinary JSON document, an author
+ <em class="rfc2119" title="MUST">MUST</em> specify an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> to a valid <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a> in
+ an HTTP Link Header [<cite><a class="bibref" href="#bib-RFC5988">RFC5988</a></cite>] using the <code>http://www.w3.org/ns/json-ld#context</code>
+ link relation. The referenced document <em class="rfc2119" title="MUST">MUST</em> have a top-level <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a>.
+ The <code>@context</code> subtree within that object is added to the top-level
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> of the referencing document. If an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>
+ is at the top-level of the referencing document and its items are
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON objects</a>, the <code>@context</code>
+ subtree is added to all <a class="tref internalDFN" title="array" href="#dfn-array">array</a> items. All extra information located outside
+ of the <code>@context</code> subtree in the referenced document <em class="rfc2119" title="MUST">MUST</em> be
+ discarded. Effectively this means that the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a> is
+ initialized with the referenced external <a class="tref internalDFN" title="context" href="#dfn-context">context</a>. A response <em class="rfc2119" title="MUST NOT">MUST NOT</em>
+ contain more than one HTTP Link Header [<cite><a class="bibref" href="#bib-RFC5988">RFC5988</a></cite>] using the
+ <code>http://www.w3.org/ns/json-ld#context</code> link relation.</p>
+
+ <p>The following example demonstrates the use of an external context with an
+ ordinary JSON document:</p>
+
+ <div class="example"><div class="example-title"><span>Example 30</span>: Referencing a JSON-LD context from a JSON document via an HTTP Link Header</div><pre class="example">GET /ordinary-json-document.json HTTP/1.1
+Host: example.com
+Accept: application/ld+json,application/json,*/*;q=0.1
+
+====================================
+
+HTTP/1.1 200 OK
+...
+Content-Type: <span class="highlight">application/json</span>
+<span class="highlight">Link: <http://json-ld.org/contexts/person.jsonld>; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"</span>
+
+{
+ "name": "Markus Lanthaler",
+ "homepage": "http://www.markus-lanthaler.com/",
+ "image": "http://twitter.com/account/profile_image/markuslanthaler"
+}</pre></div>
+
+ <p>Please note that <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD documents</a>
+ served with the <code>application/ld+json</code>
+ media type <em class="rfc2119" title="MUST">MUST</em> have all context information, including references to external
+ contexts, within the body of the document. Contexts linked via a
+ <code>http://www.w3.org/ns/json-ld#context</code> HTTP Link Header <em class="rfc2119" title="MUST">MUST</em> be
+ ignored for such documents.</p>
+</section>
+
+<section class="informative" id="string-internationalization">
+ <h3 aria-level="2" role="heading" id="h3_string-internationalization"><span class="secno">6.9 </span>String Internationalization</h3><p><em>This section is non-normative.</em></p>
+
+ <p>At times, it is important to annotate a <a class="tref internalDFN" title="string" href="#dfn-string">string</a>
+ with its language. In JSON-LD this is possible in a variety of ways.
+ First, it is possible to define a default language for a JSON-LD document
+ by setting the <code>@language</code> key in the <a class="tref internalDFN" title="context" href="#dfn-context">context</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 31</span>: Setting the default language of a JSON-LD document</div><pre class="example">{
+ <span class="highlight">"@context":
+ {
+ ...
+ "@language": "ja"
+ }</span>,
+ "name": <span class="highlight">"花澄"</span>,
+ "occupation": <span class="highlight">"科学者"</span>
+}</pre></div>
+
+ <p>The example above would associate the <code>ja</code> language
+ code with the two <a class="tref internalDFN" title="string" href="#dfn-string">strings</a> <em>花澄</em> and <em>科学者</em>.
+ Languages codes are defined in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>]. The default language applies to all
+ <a class="tref internalDFN" title="string" href="#dfn-string">string</a> values that are not <a href="#type-coercion">type coerced</a>.</p>
+
+ <p>To clear the default language for a subtree, <code>@language</code> can
+ be set to <code>null</code> in a <a class="tref internalDFN" title="local-context" href="#dfn-local-context">local context</a> as follows:</p>
+
+ <div class="example"><div class="example-title"><span>Example 32</span>: Clearing default language</div><pre class="example">{
+ "@context": {
+ ...
+ "@language": "ja"
+ },
+ "name": "花澄",
+ "details": {
+<span class="highlight"> "@context": {
+ "@language": null
+ }</span>,
+ "occupation": "Ninja"
+ }
+}</pre></div>
+
+ <p>Second, it is possible to associate a language with a specific <a class="tref internalDFN" title="term" href="#dfn-term">term</a>
+ using an <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 33</span>: Expanded term definition with language</div><pre class="example">{
+ "@context": {
+ ...
+ "ex": "http://example.com/vocab/",
+ "@language": "ja",
+ "name": { "@id": "ex:name", <span class="highlight">"@language": null</span> },
+ "occupation": { "@id": "ex:occupation" },
+ "occupation_en": { "@id": "ex:occupation", <span class="highlight">"@language": "en"</span> },
+ "occupation_cs": { "@id": "ex:occupation", <span class="highlight">"@language": "cs"</span> }
+ },
+ <span class="highlight">"name": "Yagyū Muneyoshi",
+ "occupation": "忍者",
+ "occupation_en": "Ninja",
+ "occupation_cs": "Nindža",</span>
+ ...
+}</pre></div>
+
+ <p>The example above would associate <em>忍者</em> with the specified default
+ language code <code>ja</code>, <em>Ninja</em> with the language code
+ <code>en</code>, and <em>Nindža</em> with the language code <code>cs</code>.
+ The value of <code>name</code>, <em>Yagyū Muneyoshi</em> wouldn't be
+ associated with any language code since <code>@language</code> was reset to
+ <a class="tref internalDFN" title="null" href="#dfn-null">null</a> in the <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a>.</p>
+
+ <div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_6"><span>Note</span></div><p class="">Language associations are only applied to plain
+ <a class="tref internalDFN" title="string" href="#dfn-string">strings</a>. <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">Typed values</a>
+ or values that are subject to <a href="#type-coercion">type coercion</a>
+ are not language tagged.</p></div>
+
+ <p>Just as in the example above, systems often need to express the value of a
+ property in multiple languages. Typically, such systems also try to ensure that
+ developers have a programmatically easy way to navigate the data structures for
+ the language-specific data. In this case, <a class="tref internalDFN" title="language-map" href="#dfn-language-map">language maps</a>
+ may be utilized.</p>
+
+ <div class="example"><div class="example-title"><span>Example 34</span>: Language map expressing a property in three languages</div><pre class="example">{
+ "@context":
+ {
+ ...
+ "occupation": { "@id": "ex:occupation", <span class="highlight">"@container": "@language"</span> }
+ },
+ "name": "Yagyū Muneyoshi",
+ "occupation":
+ <span class="highlight">{
+ "ja": "忍者",
+ "en": "Ninja",
+ "cs": "Nindža"
+ }</span>
+ ...
+}</pre></div>
+
+ <p>The example above expresses exactly the same information as the previous
+ example but consolidates all values in a single property. To access the
+ value in a specific language in a programming language supporting dot-notation
+ accessors for object properties, a developer may use the
+ <code>property.language</code> pattern. For example, to access the occupation
+ in English, a developer would use the following code snippet:
+ <code>obj.occupation.en</code>.</p>
+
+ <p>Third, it is possible to override the default language by using a
+ <a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 35</span>: Overriding default language using an expanded value</div><pre class="example">{
+ "@context": {
+ ...
+ "@language": "ja"
+ },
+ "name": "花澄",
+ "occupation": <span class="highlight">{
+ "@value": "Scientist",
+ "@language": "en"
+ }</span>
+}</pre></div>
+
+ <p>This makes it possible to specify a plain string by omitting the
+ <code>@language</code> tag or setting it to <code>null</code> when expressing
+ it using a <a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 36</span>: Removing language information using an expanded value</div><pre class="example">{
+ "@context": {
+ ...
+ "@language": "ja"
+ },
+ "name": <span class="highlight">{
+ "@value": "Frank"
+ }</span>,
+ "occupation": {
+ "@value": "Ninja",
+ "@language": "en"
+ },
+ "speciality": "手裏剣"
+}</pre></div>
+
+</section>
+
+<section class="informative" id="iri-expansion-within-a-context">
+ <h3 aria-level="2" role="heading" id="h3_iri-expansion-within-a-context"><span class="secno">6.10 </span><abbr title="Internationalized Resource Identifier">IRI</abbr> Expansion within a Context</h3><p><em>This section is non-normative.</em></p>
+ <p>In general, normal <abbr title="Internationalized Resource Identifier">IRI</abbr> expansion rules apply
+ anywhere an <abbr title="Internationalized Resource Identifier">IRI</abbr> is expected (see <a class="sectionRef sec-ref" href="#iris">section 5.2 IRIs</a>). Within
+ a <a class="tref internalDFN" title="context" href="#dfn-context">context</a> definition, this can mean that terms defined
+ within the context may also be used within that context as long as
+ there are no circular dependencies. For example, it is common to use
+ the <code>xsd</code> namespace when defining <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed value</a>s:</p>
+
+<div class="example"><div class="example-title"><span>Example 37</span>: IRI expansion within a context</div><pre class="example">{
+ "@context":
+ {
+ <span class="highlight">"xsd": "http://www.w3.org/2001/XMLSchema#"</span>,
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "age":
+ {
+ "@id": "http://xmlns.com/foaf/0.1/age",
+ "@type": <span class="highlight">"xsd:integer"</span>
+ },
+ "homepage":
+ {
+ "@id": "http://xmlns.com/foaf/0.1/homepage",
+ "@type": "@id"
+ }
+ },
+ ...
+}</pre></div>
+
+<p>In this example, the <code>xsd</code> <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is defined
+ and used as a <a class="tref internalDFN" title="prefix" href="#dfn-prefix">prefix</a> for the <code>@type</code> coercion
+ of the <code>age</code> property.</p>
+
+<p><a class="tref internalDFN" title="term" href="#dfn-term">Terms</a> may also be used when defining the <abbr title="Internationalized Resource Identifier">IRI</abbr> of another
+<a class="tref internalDFN" title="term" href="#dfn-term">term</a>:</p>
+
+<div class="example"><div class="example-title"><span>Example 38</span>: Using a term to define the IRI of another term within a context</div><pre class="example">{
+ "@context":
+ {
+ <span class="highlight">"foaf": "http://xmlns.com/foaf/0.1/"</span>,
+ "xsd": "http://www.w3.org/2001/XMLSchema#",
+ "name": <span class="highlight">"foaf:name"</span>,
+ "age":
+ {
+ "@id": <span class="highlight">"foaf:age"</span>,
+ "@type": "xsd:integer"
+ },
+ "homepage":
+ {
+ "@id": <span class="highlight">"foaf:homepage"</span>,
+ "@type": "@id"
+ }
+ },
+ ...
+}</pre></div>
+
+<p><a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">Compact IRIs</a>
+ and <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> may be used on the left-hand side of a
+ <a class="tref internalDFN" title="term" href="#dfn-term">term</a> definition.</p>
+
+<div class="example"><div class="example-title"><span>Example 39</span>: Using a compact IRI as a term</div><pre class="example">{
+ "@context":
+ {
+ <span class="highlight">"foaf": "http://xmlns.com/foaf/0.1/"</span>,
+ "xsd": "http://www.w3.org/2001/XMLSchema#",
+ "name": "foaf:name",
+ "<span class="highlight">foaf:age</span>":
+ {
+ "@type": "xsd:integer"
+ },
+ "<span class="highlight">foaf:homepage</span>":
+ <span class="highlight">{
+ "@type": "@id"
+ }</span>
+ },
+ ...
+}</pre></div>
+
+<p>
+In this example, the <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> form is used in two different
+ways.
+In the first approach, <code>foaf:age</code> declares both the
+<a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> for the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> (using short-form) as well as the
+<code>@type</code> associated with the <a class="tref internalDFN" title="term" href="#dfn-term">term</a>. In the second
+approach, only the <code>@type</code> associated with the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is
+specified. The full <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> for
+<code>foaf:homepage</code> is determined by looking up the <code>foaf</code>
+<a class="tref internalDFN" title="prefix" href="#dfn-prefix">prefix</a> in the
+<a class="tref internalDFN" title="context" href="#dfn-context">context</a>.
+</p>
+
+<p>
+<a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">Absolute IRIs</a> may also be used in the key position in a <a class="tref internalDFN" title="context" href="#dfn-context">context</a>:
+</p>
+
+<div class="example"><div class="example-title"><span>Example 40</span>: Associating context definitions with absolute IRIs</div><pre class="example">{
+ "@context":
+ {
+ "foaf": "http://xmlns.com/foaf/0.1/",
+ "xsd": "http://www.w3.org/2001/XMLSchema#",
+ "name": "foaf:name",
+ "foaf:age":
+ {
+ "@id": "foaf:age",
+ "@type": "xsd:integer"
+ },
+ "<span class="highlight">http://xmlns.com/foaf/0.1/homepage</span>":
+ {
+ "@type": "@id"
+ }
+ },
+ ...
+}</pre></div>
+
+<p>In order for the <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> to match above, the <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ needs to be used in the <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a>. Also note that <code>foaf:homepage</code>
+ will not use the <code>{ "@type": "@id" }</code> declaration because
+ <code>foaf:homepage</code> is not the same as <code>http://xmlns.com/foaf/0.1/homepage</code>.
+ That is, <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> are looked up in a <a class="tref internalDFN" title="context" href="#dfn-context">context</a> using
+ direct string comparison before the <a class="tref internalDFN" title="prefix" href="#dfn-prefix">prefix</a> lookup mechanism is applied.</p>
+
+<div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_7"><span>Note</span></div><p class="">While it is possible to define a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, or
+ an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> to expand to some other unrelated <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ (for example, <code>foaf:name</code> expanding to
+ <code>http://example.org/unrelated#species</code>), such usage is strongly
+ discouraged.</p></div>
+
+<p>The only exception for using terms in the <a class="tref internalDFN" title="context" href="#dfn-context">context</a> is that
+ circular definitions are not allowed. That is,
+ a definition of <em>term1</em> cannot depend on the
+ definition of <em>term2</em> if <em>term2</em> also depends on
+ <em>term1</em>. For example, the following <a class="tref internalDFN" title="context" href="#dfn-context">context</a> definition
+ is illegal:</p>
+<div class="example"><div class="example-title"><span>Example 41</span>: Illegal circular definition of terms within a context</div><pre class="example">{
+ "@context":
+ {
+ <span class="highlight">"term1": "term2:foo",
+ "term2": "term1:bar"</span>
+ },
+ ...
+}</pre></div>
+</section>
+
+<section class="informative" id="sets-and-lists">
+<h3 aria-level="2" role="heading" id="h3_sets-and-lists"><span class="secno">6.11 </span>Sets and Lists</h3><p><em>This section is non-normative.</em></p>
+
+<p>A JSON-LD author can express multiple values in a compact way by using
+ <a class="tref internalDFN" title="array" href="#dfn-array">arrays</a>. Since graphs do not describe ordering for links
+ between nodes, arrays in JSON-LD do not provide an ordering of the
+ contained elements by default. This is exactly the opposite from regular JSON
+ arrays, which are ordered by default. For example, consider the following
+ simple document:</p>
+
+<div class="example"><div class="example-title"><span>Example 42</span>: Multiple values with no inherent order</div><pre class="example">{
+...
+ "@id": "http://example.org/people#joebob",
+ "nick": <span class="highlight">[ "joe", "bob", "JB" ]</span>,
+...
+}</pre></div>
+
+<p>The example shown above would result in the following data being generated,
+ each relating the node to an individual value, with no inherent order:</p>
+
+<table class="example">
+<thead>
+ <tr><th>Subject</th>
+ <th>Property</th>
+ <th>Value</th>
+</tr></thead>
+<tbody>
+<tr>
+ <td>http://example.org/people#joebob</td>
+ <td>http://xmlns.com/foaf/0.1/nick</td>
+ <td>joe</td>
+</tr>
+<tr>
+ <td>http://example.org/people#joebob</td>
+ <td>http://xmlns.com/foaf/0.1/nick</td>
+ <td>bob</td>
+</tr>
+<tr>
+ <td>http://example.org/people#joebob</td>
+ <td>http://xmlns.com/foaf/0.1/nick</td>
+ <td>JB</td>
+</tr>
+</tbody>
+</table>
+
+<p>Multiple values may also be expressed using the expanded form:</p>
+
+<div class="example"><div class="example-title"><span>Example 43</span>: Using an expanded form to set multiple values</div><pre class="example">{
+ "@id": "http://example.org/articles/8",
+ "dc:title": <span class="highlight">
+ [
+ {
+ "@value": "Das Kapital",
+ "@language": "de"
+ },
+ {
+ "@value": "Capital",
+ "@language": "en"
+ }
+ ]</span>
+}</pre></div>
+
+<p>The example shown above would generate the following data, again with
+ no inherent order:</p>
+
+<table class="example">
+<thead>
+ <tr><th>Subject</th>
+ <th>Property</th>
+ <th>Value</th>
+ <th>Language</th>
+</tr></thead>
+<tbody>
+<tr>
+ <td>http://example.org/articles/8</td>
+ <td>http://purl.org/dc/terms/title</td>
+ <td>Das Kapital</td>
+ <td>de</td>
+</tr>
+<tr>
+ <td>http://example.org/articles/8</td>
+ <td>http://purl.org/dc/terms/title</td>
+ <td>Capital</td>
+ <td>en</td>
+</tr>
+</tbody>
+</table>
+
+<p>As the notion of ordered collections is rather important in data
+ modeling, it is useful to have specific language support. In JSON-LD,
+ a list may be represented using the <code>@list</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> as follows:</p>
+<div class="example"><div class="example-title"><span>Example 44</span>: An ordered collection of values in JSON-LD</div><pre class="example">{
+...
+ "@id": "http://example.org/people#joebob",
+ "foaf:nick":
+ <span class="highlight">{
+ "@list": [ "joe", "bob", "jaybee" ]
+ }</span>,
+...
+}</pre></div>
+
+<p>This describes the use of this <a class="tref internalDFN" title="array" href="#dfn-array">array</a> as being ordered,
+ and order is maintained when processing a document. If every use of a given multi-valued
+ property is a list, this may be abbreviated by setting <code>@container</code>
+ to <code>@list</code> in the <a class="tref internalDFN" title="context" href="#dfn-context">context</a>:</p>
+<div class="example"><div class="example-title"><span>Example 45</span>: Specifying that a collection is ordered in the context</div><pre class="example">{
+ <span class="highlight">"@context":
+ {
+ ...
+ "nick":
+ {
+ "@id": "http://xmlns.com/foaf/0.1/nick",
+ "@container": "@list"
+ }
+ }</span>,
+...
+ "@id": "http://example.org/people#joebob",
+ "nick": <span class="highlight">[ "joe", "bob", "jaybee" ]</span>,
+...
+}</pre></div>
+
+<div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_8"><span>Note</span></div><p class="">List of lists in the form of <a class="tref internalDFN" title="list-object" href="#dfn-list-object">list objects</a>
+ are not allowed in this version of JSON-LD. This decision was made due to the
+ extreme amount of added complexity when processing lists of lists.</p></div>
+
+<p>While <code>@list</code> is used to describe <em>ordered lists</em>,
+ the <code>@set</code> keyword is used to describe <em>unordered sets</em>.
+ The use of <code>@set</code> in the body of a JSON-LD document
+ is optimized away when processing the document, as it is just syntactic
+ sugar. However, <code>@set</code> is helpful when used within the context
+ of a document.
+ Values of terms associated with a <code>@set</code> or <code>@list</code> container
+ are always represented in the form of an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>,
+ even if there is just a single value that would otherwise be optimized to
+ a non-array form in compact form (see
+ <a class="sectionRef sec-ref" href="#compacted-document-form">section 6.18 Compacted Document Form</a>). This makes post-processing of
+ JSON-LD documents easier as the data is always in array form, even if the
+ array only contains a single value.</p>
+
+</section>
+
+<section class="informative" id="reverse-properties">
+ <h3 aria-level="2" role="heading" id="h3_reverse-properties"><span class="secno">6.12 </span>Reverse Properties</h3><p><em>This section is non-normative.</em></p>
+
+ <p>JSON-LD serializes directed <a class="tref internalDFN" title="graph" href="#dfn-graph">graphs</a>. That means that
+ every <a class="tref internalDFN" title="property" href="#dfn-property">property</a> points from a <a class="tref internalDFN" title="node" href="#dfn-node">node</a> to another <a class="tref internalDFN" title="node" href="#dfn-node">node</a>
+ or <a class="tref internalDFN" title="json-ld-value" href="#dfn-json-ld-value">value</a>. However, in some cases, it is desirable
+ to serialize in the reverse direction. Consider for example the case where a person
+ and its children should be described in a document. If the used vocabulary does not
+ provide a <em>children</em> <a class="tref internalDFN" title="property" href="#dfn-property">property</a> but just a <em>parent</em>
+ <a class="tref internalDFN" title="property" href="#dfn-property">property</a>, every <a class="tref internalDFN" title="node" href="#dfn-node">node</a> representing a child would have to
+ be expressed with a <a class="tref internalDFN" title="property" href="#dfn-property">property</a> pointing to the parent as in the following
+ example.</p>
+
+ <div class="example"><div class="example-title"><span>Example 46</span>: A document with children linking to their parent</div><pre class="example">[
+ {
+ <span class="highlight">"@id": "#homer"</span>,
+ "http://example.com/vocab#name": "Homer"
+ },
+ {
+ "@id": "#bart",
+ "http://example.com/vocab#name": "Bart",
+ <span class="highlight">"http://example.com/vocab#parent": { "@id": "#homer" }</span>
+ },
+ {
+ "@id": "#lisa",
+ "http://example.com/vocab#name": "Lisa",
+ <span class="highlight">"http://example.com/vocab#parent": { "@id": "#homer" }</span>
+ }
+]</pre></div>
+
+ <p>Expressing such data is much simpler by using JSON-LD's <code>@reverse</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 47</span>: A person and its children using a reverse property</div><pre class="example">{
+ "@id": "#homer",
+ "http://example.com/vocab#name": "Homer",
+ <span class="highlight">"@reverse"</span>: {
+ <span class="highlight">"http://example.com/vocab#parent"</span>: [
+ {
+ "@id": "#bart",
+ "http://example.com/vocab#name": "Bart"
+ },
+ {
+ "@id": "#lisa",
+ "http://example.com/vocab#name": "Lisa"
+ }
+ ]
+ }
+}</pre></div>
+
+ <p>The <code>@reverse</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> can also be used in
+ <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definitions</a>
+ to create reverse properties as shown in the following example:</p>
+
+
+ <div class="example"><div class="example-title"><span>Example 48</span>: Using @reverse to define reverse properties</div><pre class="example">{
+ "@context": {
+ "name": "http://example.com/vocab#name",
+ <span class="highlight">"children": { "@reverse": "http://example.com/vocab#parent" }</span>
+ },
+ "@id": "#homer",
+ "name": "Homer",
+ <span class="highlight">"children"</span>: [
+ {
+ "@id": "#bart",
+ "name": "Bart"
+ },
+ {
+ "@id": "#lisa",
+ "name": "Lisa"
+ }
+ ]
+}</pre></div>
+</section>
+
+
+<section class="informative" id="named-graphs">
+ <h3 aria-level="2" role="heading" id="h3_named-graphs"><span class="secno">6.13 </span>Named Graphs</h3><p><em>This section is non-normative.</em></p>
+
+ <p>At times, it is necessary to make statements about a <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a>
+ itself, rather than just a single <a class="tref internalDFN" title="node" href="#dfn-node">node</a>. This can be done by
+ grouping a set of <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a> using the <code>@graph</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>. A developer may also name data expressed using the
+ <code>@graph</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> by pairing it with an
+ <code>@id</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> as shown in the following example:</p>
+
+ <div class="example"><div class="example-title"><span>Example 49</span>: Identifying and making statements about a graph</div><pre class="example">{
+ "@context": {
+ "generatedAt": {
+ "@id": "http://www.w3.org/ns/prov#generatedAtTime",
+ "@type": "http://www.w3.org/2001/XMLSchema#date"
+ },
+ "Person": "http://xmlns.com/foaf/0.1/Person",
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "knows": "http://xmlns.com/foaf/0.1/knows"
+ },
+ <span class="highlight">"@id": "http://example.org/graphs/73",
+ "generatedAt": "2012-04-09",
+ "@graph":</span>
+ [
+ {
+ "@id": "http://manu.sporny.org/about#manu",
+ "@type": "Person",
+ "name": "Manu Sporny",
+ "knows": "http://greggkellogg.net/foaf#me"
+ },
+ {
+ "@id": "http://greggkellogg.net/foaf#me",
+ "@type": "Person",
+ "name": "Gregg Kellogg",
+ "knows": "http://manu.sporny.org/about#manu"
+ }
+ ]
+}</pre></div>
+
+ <p>The example above expresses a <a class="tref internalDFN" title="named-graph" href="#dfn-named-graph">named graph</a> that is identified
+ by the <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> <code>http://example.org/graphs/73</code>. That
+ graph is composed of the statements about Manu and Gregg. Metadata about
+ the graph itself is expressed via the <code>generatedAt</code> property,
+ which specifies when the graph was generated. An alternative view of the
+ information above is represented in table form below:</p>
+
+ <table class="example">
+ <thead>
+ <tr><th>Graph</th>
+ <th>Subject</th>
+ <th>Property</th>
+ <th>Value</th>
+ <th>Value Type</th>
+ </tr></thead>
+ <tbody>
+ <tr>
+ <td> </td>
+ <td>http://example.org/graphs/73</td>
+ <td>http://www.w3.org/ns/prov#generatedAtTime</td>
+ <td>2012-04-09</td>
+ <td>http://www.w3.org/2001/XMLSchema#date</td>
+ </tr>
+ <tr>
+ <td>http://example.org/graphs/73</td>
+ <td>http://manu.sporny.org/about#manu</td>
+ <td>http://www.w3.org/2001/XMLSchema#type</td>
+ <td>http://xmlns.com/foaf/0.1/Person</td>
+ <td></td>
+ </tr>
+ <tr>
+ <td>http://example.org/graphs/73</td>
+ <td>http://manu.sporny.org/about#manu</td>
+ <td>http://xmlns.com/foaf/0.1/name</td>
+ <td>Manu Sporny</td>
+ <td></td>
+ </tr>
+ <tr>
+ <td>http://example.org/graphs/73</td>
+ <td>http://manu.sporny.org/about#manu</td>
+ <td>http://xmlns.com/foaf/0.1/knows</td>
+ <td>http://greggkellogg.net/foaf#me</td>
+ <td></td>
+ </tr>
+ <tr>
+ <td>http://example.org/graphs/73</td>
+ <td>http://greggkellogg.net/foaf#me</td>
+ <td>http://www.w3.org/2001/XMLSchema#type</td>
+ <td>http://xmlns.com/foaf/0.1/Person</td>
+ <td></td>
+ </tr>
+ <tr>
+ <td>http://example.org/graphs/73</td>
+ <td>http://greggkellogg.net/foaf#me</td>
+ <td>http://xmlns.com/foaf/0.1/name</td>
+ <td>Gregg Kellogg</td>
+ <td></td>
+ </tr>
+ <tr>
+ <td>http://example.org/graphs/73</td>
+ <td>http://greggkellogg.net/foaf#me</td>
+ <td>http://xmlns.com/foaf/0.1/knows</td>
+ <td>http://manu.sporny.org/about#manu</td>
+ <td></td>
+ </tr>
+ </tbody>
+ </table>
+
+ <p>When a JSON-LD document's top-level structure is an
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">object</a> that contains no other
+ <a class="tref internalDFN" title="property" href="#dfn-property">properties</a> than <code>@graph</code> and
+ optionally <code>@context</code> (properties that are not mapped to an
+ <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> are ignored),
+ <code>@graph</code> is considered to express the otherwise implicit
+ <a class="tref internalDFN" title="default-graph" href="#dfn-default-graph">default graph</a>. This mechanism can be useful when a number
+ of <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a> exist at the document's top level that
+ share the same <a class="tref internalDFN" title="context" href="#dfn-context">context</a>, which is, e.g., the case when a
+ document is <a href="#flattened-document-form">flattened</a>. The
+ <code>@graph</code> keyword collects such nodes in an <a class="tref internalDFN" title="array" href="#dfn-array">array</a>
+ and allows the use of a shared context.</p>
+
+ <div class="example"><div class="example-title"><span>Example 50</span>: Using @graph to explicitly express the default graph</div><pre class="example">{
+ "@context": ...,
+ "<span class="highlight">@graph</span>":
+ [
+ {
+ "@id": "http://manu.sporny.org/about#manu",
+ "@type": "foaf:Person",
+ "name": "Manu Sporny",
+ "knows": "http://greggkellogg.net/foaf#me"
+ },
+ {
+ "@id": "http://greggkellogg.net/foaf#me",
+ "@type": "foaf:Person",
+ "name": "Gregg Kellogg",
+ "knows": "http://manu.sporny.org/about#manu"
+ }
+ ]
+}</pre></div>
+
+ <p>In this case, embedding doesn't work as each <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>
+ references the other. This is equivalent to using multiple
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a> in array and defining
+ the <code>@context</code> within each <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>:</p>
+
+ <div class="example"><div class="example-title"><span>Example 51</span>: Context needs to be duplicated if @graph is not used</div><pre class="example">[
+ {
+ <span class="highlight">"@context": ...,</span>
+ "@id": "http://manu.sporny.org/about#manu",
+ "@type": "foaf:Person",
+ "name": "Manu Sporny",
+ "knows": "http://greggkellogg.net/foaf#me"
+ },
+ {
+ <span class="highlight">"@context": ...,</span>
+ "@id": "http://greggkellogg.net/foaf#me",
+ "@type": "foaf:Person",
+ "name": "Gregg Kellogg",
+ "knows": "http://manu.sporny.org/about#manu"
+ }
+]</pre></div>
+
+</section>
+
+<section class="informative" id="identifying-blank-nodes">
+ <h3 aria-level="2" role="heading" id="h3_identifying-blank-nodes"><span class="secno">6.14 </span>Identifying Blank Nodes</h3><p><em>This section is non-normative.</em></p>
+
+ <p>At times, it becomes necessary to be able to express information without
+ being able to uniquely identify the <a class="tref internalDFN" title="node" href="#dfn-node">node</a> with an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
+ This type of node is called a <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank node</a>. JSON-LD does not require
+ all nodes to be identified using <code>@id</code>. However, some graph topologies
+ may require identifiers to be serializable. Graphs containing loops, e.g., cannot
+ be serialized using embedding alone, <code>@id</code> must be used to connect the nodes.
+ In these situations, one can use <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifiers</a>,
+ which look like <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> using an underscore (<code>_</code>)
+ as scheme. This allows one to reference the node locally within the document, but
+ makes it impossible to reference the node from an external document. The
+ <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a> is scoped to the document in which it is used.</p>
+
+ <div class="example"><div class="example-title"><span>Example 52</span>: Specifying a local blank node identifier</div><pre class="example">{
+ ...
+ "@id": "<span class="highlight">_:n1</span>",
+ "name": "Secret Agent 1",
+ "knows":
+ {
+ "name": "Secret Agent 2",
+ "knows": { "@id": "<span class="highlight">_:n1</span>" }
+ }
+}</pre></div>
+
+ <p>The example above contains information about to secret agents that cannot be identified
+ with an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. While expressing that <em>agent 1</em> knows <em>agent 2</em> is possible
+ without using <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifiers</a>, it is
+ necessary assign <em>agent 1</em> an identifier so that it can be referenced from
+ <em>agent 2</em>.</p>
+ <p>It is worth nothing that blank node identifiers may be relabeled during processing.
+ If a developer finds that they refer to the <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank node</a> more than once,
+ they should consider naming the node using a dereferenceable <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> so that
+ it can also be referenced from other documents.</p>
+</section>
+
+<section class="informative" id="aliasing-keywords">
+ <h3 aria-level="2" role="heading" id="h3_aliasing-keywords"><span class="secno">6.15 </span>Aliasing Keywords</h3><p><em>This section is non-normative.</em></p>
+
+ <p>Each of the JSON-LD <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a>,
+ except for <code>@context</code>, may be aliased to application-specific
+ keywords. This feature allows legacy JSON content to be utilized
+ by JSON-LD by re-using JSON keys that already exist in legacy documents.
+ This feature also allows developers to design domain-specific implementations
+ using only the JSON-LD <a class="tref internalDFN" title="context" href="#dfn-context">context</a>.</p>
+
+ <div class="example"><div class="example-title"><span>Example 53</span>: Aliasing keywords</div><pre class="example">{
+ "@context":
+ {
+ <span class="highlight">"url": "@id"</span>,
+ <span class="highlight">"a": "@type"</span>,
+ "name": "http://xmlns.com/foaf/0.1/name"
+ },
+ "<span class="highlight">url</span>": "http://example.com/about#gregg",
+ "<span class="highlight">a</span>": "http://xmlns.com/foaf/0.1/Person",
+ "name": "Gregg Kellogg"
+}</pre></div>
+
+ <p>In the example above, the <code>@id</code> and <code>@type</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> have been given the aliases
+ <strong>url</strong> and <strong>a</strong>, respectively.</p>
+
+ <p>Since keywords cannot be redefined, they can also not be aliased to
+ other keywords.</p>
+</section>
+
+<section class="informative" id="data-indexing">
+ <h3 aria-level="2" role="heading" id="h3_data-indexing"><span class="secno">6.16 </span>Data Indexing</h3><p><em>This section is non-normative.</em></p>
+
+ <p>Databases are typically used to make access to
+ data more efficient. Developers often extend this sort of functionality into
+ their application data to deliver similar performance gains. Often this
+ data does not have any meaning from a Linked Data standpoint, but is
+ still useful for an application.</p>
+
+ <p>JSON-LD introduces the notion of <a class="tref internalDFN" title="index-map" href="#dfn-index-map">index maps</a>
+ that can be used to structure data into a form that is
+ more efficient to access. The data indexing feature allows an author to
+ structure data using a simple key-value map where the keys do not map
+ to <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>. This enables direct access to data
+ instead of having to scan an array in search of a specific item.
+ In JSON-LD such data can be specified by associating the
+ <code>@index</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> with a
+ <code>@container</code> declaration in the context:</p>
+
+ <div class="example"><div class="example-title"><span>Example 54</span>: Indexing data in JSON-LD</div><pre class="example">{
+ "@context":
+ {
+ "schema": "http://schema.org/",
+ "name": "schema:name",
+ "body": "schema:articleBody",
+ "words": "schema:wordCount",
+ "post": {
+ "@id": "schema:blogPost",
+ <span class="highlight">"@container": "@index"</span>
+ }
+ },
+ "@id": "http://example.com/",
+ "@type": "schema:Blog",
+ "name": "World Financial News",
+ <span class="highlight">"post": {
+ "en": {
+ "@id": "http://example.com/posts/1/en",
+ "body": "World commodities were up today with heavy trading of crude oil...",
+ "words": 1539
+ },
+ "de": {
+ "@id": "http://example.com/posts/1/de",
+ "body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
+ "words": 1204
+ }</span>
+ }
+}</pre></div>
+
+ <p>In the example above, the <strong>blogPost</strong> <a class="tref internalDFN" title="term" href="#dfn-term">term</a> has
+ been marked as an <a class="tref internalDFN" title="index-map" href="#dfn-index-map">index map</a>. The <strong>en</strong>,
+ <strong>de</strong>, and <strong>ja</strong> keys will be ignored
+ semantically, but preserved syntactically, by the JSON-LD Processor.
+ This allows a developer to access the German version
+ of the <strong>blogPost</strong> using the following code snippet:
+ <code>obj.blogPost.de</code>.</p>
+
+ <p>The interpretation of the data above is expressed in
+ the table below. Note how the index keys do not appear in the Linked Data
+ below, but would continue to exist if the document were compacted or
+ expanded (see <a class="sectionRef sec-ref" href="#compacted-document-form">section 6.18 Compacted Document Form</a> and
+ <a class="sectionRef sec-ref" href="#expanded-document-form">section 6.17 Expanded Document Form</a>) using a JSON-LD processor:</p>
+
+ <table class="example">
+ <thead>
+ <tr><th>Subject</th>
+ <th>Property</th>
+ <th>Value</th>
+ </tr></thead>
+ <tbody>
+ <tr>
+ <td>http://example.com/</td>
+ <td>http://www.w3.org/1999/02/22-rdf-syntax-ns#type</td>
+ <td>http://schema.org/Blog</td>
+ </tr>
+ <tr>
+ <td>http://example.com/</td>
+ <td>http://schema.org/name</td>
+ <td>World Financial News</td>
+ </tr>
+ <tr>
+ <td>http://example.com/</td>
+ <td>http://schema.org/blogPost</td>
+ <td>http://example.com/posts/1/en</td>
+ </tr>
+ <tr>
+ <td>http://example.com/</td>
+ <td>http://schema.org/blogPost</td>
+ <td>http://example.com/posts/1/de</td>
+ </tr>
+ <tr>
+ <td>http://example.com/posts/1/en</td>
+ <td>http://schema.org/articleBody</td>
+ <td>World commodities were up today with heavy trading of crude oil...</td>
+ </tr>
+ <tr>
+ <td>http://example.com/posts/1/en</td>
+ <td>http://schema.org/wordCount</td>
+ <td>1539</td>
+ </tr>
+ <tr>
+ <td>http://example.com/posts/1/de</td>
+ <td>http://schema.org/articleBody</td>
+ <td>Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...</td>
+ </tr>
+ <tr>
+ <td>http://example.com/posts/1/de</td>
+ <td>http://schema.org/wordCount</td>
+ <td>1204</td>
+ </tr>
+ </tbody>
+ </table>
+</section>
+
+<section class="informative" id="expanded-document-form">
+ <h3 aria-level="2" role="heading" id="h3_expanded-document-form"><span class="secno">6.17 </span>Expanded Document Form</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The JSON-LD Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>]
+ defines a method for <em>expanding</em> a JSON-LD document.
+ Expansion is the process of taking a JSON-LD document and applying a
+ <code>@context</code> such that all IRIs, types, and values
+ are expanded so that the <code>@context</code> is no longer necessary.</p>
+
+ <p>For example, assume the following JSON-LD input document:</p>
+
+ <div class="example"><div class="example-title"><span>Example 55</span>: Sample JSON-LD document</div><pre class="example">{
+ "@context":
+ {
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "homepage": {
+ "@id": "http://xmlns.com/foaf/0.1/homepage",
+ "@type": "@id"
+ }
+ },
+ "name": "Manu Sporny",
+ "homepage": "http://manu.sporny.org/"
+}</pre></div>
+
+ <p>Running the JSON-LD Expansion algorithm against the JSON-LD input document
+ provided above would result in the following output:</p>
+
+ <div class="example"><div class="example-title"><span>Example 56</span>: Expanded form for the previous example</div><pre class="example">[
+ {
+ "http://xmlns.com/foaf/0.1/name": [
+ { "@value": "Manu Sporny" }
+ ],
+ "http://xmlns.com/foaf/0.1/homepage": [
+ { "@id": "http://manu.sporny.org/" }
+ ]
+ }
+]</pre></div>
+
+ <p><a href="#application-ld-json">JSON-LD's media type</a> defines a
+ <code>profile</code> parameter which can be used to signal or request
+ expanded document form. The profile URI identifying expanded document
+ form is <code>http://www.w3.org/ns/json-ld#expanded</code>.</p>
+</section>
+
+<section class="informative" id="compacted-document-form">
+ <h3 aria-level="2" role="heading" id="h3_compacted-document-form"><span class="secno">6.18 </span>Compacted Document Form</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The JSON-LD Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>] defines
+ a method for <em>compacting</em> a JSON-LD document. Compaction is the process
+ of applying a developer-supplied context to shorten <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>
+ to <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> or <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact IRIs</a>
+ and JSON-LD values expressed in expanded form to simple values such as
+ <a class="tref internalDFN" title="string" href="#dfn-string">strings</a> or <a class="tref internalDFN" title="number" href="#dfn-number">numbers</a>.
+ Often this makes it simpler to work with document as the data is expressed in
+ application-specific terms. Compacted documents are also typically easier to read
+ for humans.</p>
+
+ <p>For example, assume the following JSON-LD input document:</p>
+
+ <div class="example"><div class="example-title"><span>Example 57</span>: Sample expanded JSON-LD document</div><pre class="example">[
+ {
+ "http://xmlns.com/foaf/0.1/name": [ "Manu Sporny" ],
+ "http://xmlns.com/foaf/0.1/homepage": [
+ {
+ "@id": "http://manu.sporny.org/"
+ }
+ ]
+ }
+]</pre></div>
+
+ <p>Additionally, assume the following developer-supplied JSON-LD context:</p>
+
+ <div class="example"><div class="example-title"><span>Example 58</span>: Sample context</div><pre class="example">{
+ "@context": {
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "homepage": {
+ "@id": "http://xmlns.com/foaf/0.1/homepage",
+ "@type": "@id"
+ }
+ }
+}</pre></div>
+
+ <p>Running the JSON-LD Compaction algorithm given the context supplied above
+ against the JSON-LD input document provided above would result in the following
+ output:</p>
+
+ <div class="example"><div class="example-title"><span>Example 59</span>: Compact form of the sample document once sample context has been applied</div><pre class="example">{
+ "@context": {
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "homepage": {
+ "@id": "http://xmlns.com/foaf/0.1/homepage",
+ "@type": "@id"
+ }
+ },
+ "name": "Manu Sporny",
+ "homepage": "http://manu.sporny.org/"
+}</pre></div>
+
+ <p><a href="#application-ld-json">JSON-LD's media type</a> defines a
+ <code>profile</code> parameter which can be used to signal or request
+ compacted document form. The profile URI identifying compacted document
+ form is <code>http://www.w3.org/ns/json-ld#compacted</code>.</p>
+</section>
+
+<section class="informative" id="flattened-document-form">
+ <h3 aria-level="2" role="heading" id="h3_flattened-document-form"><span class="secno">6.19 </span>Flattened Document Form</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The JSON-LD Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>] defines
+ a method for <em>flattening</em> a JSON-LD document. Flattening collects all
+ properties of a <a class="tref internalDFN" title="node" href="#dfn-node">node</a> in a single <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> and labels
+ all <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a> with
+ <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifiers</a>.
+ This ensures a shape of the data and consequently may drastically simplify the code
+ required to process JSON-LD in certain applications.</p>
+
+ <p>For example, assume the following JSON-LD input document:</p>
+
+ <div class="example"><div class="example-title"><span>Example 60</span>: Sample JSON-LD document</div><pre class="example">{
+ "@context": {
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "knows": "http://xmlns.com/foaf/0.1/knows"
+ },
+ "@id": "http://me.markus-lanthaler.com/",
+ "name": "Markus Lanthaler",
+ "knows": [
+ {
+ "@id": "http://manu.sporny.org/about#manu",
+ "name": "Manu Sporny"
+ },
+ {
+ "name": "Dave Longley"
+ }
+ ]
+}</pre></div>
+
+ <p>Running the JSON-LD Flattening algorithm against the JSON-LD input document in
+ the example above and using the same context would result in the following
+ output:</p>
+
+ <div class="example"><div class="example-title"><span>Example 61</span>: Flattened and compacted form for the previous example</div><pre class="example">{
+ "@context": {
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "knows": "http://xmlns.com/foaf/0.1/knows"
+ },
+ "@graph": [
+ {
+ "@id": "_:b0",
+ "name": "Dave Longley"
+ },
+ {
+ "@id": "http://manu.sporny.org/about#manu",
+ "name": "Manu Sporny"
+ },
+ {
+ "@id": "http://me.markus-lanthaler.com/",
+ "name": "Markus Lanthaler",
+ "knows": [
+ { "@id": "http://manu.sporny.org/about#manu" },
+ { "@id": "_:b0" }
+ ]
+ }
+ ]
+}</pre></div>
+
+ <p><a href="#application-ld-json">JSON-LD's media type</a> defines a
+ <code>profile</code> parameter which can be used to signal or request
+ flattened document form. The profile URI identifying flattened document
+ form is <code>http://www.w3.org/ns/json-ld#flattened</code>. It can be
+ combined with the profile URI identifying
+ <a href="#expanded-document-form">expanded document form</a> or
+ <a href="#compacted-document-form">compacted document from</a>.</p>
+</section>
+
+<section class="informative" id="embedding-json-ld-in-html-documents">
+ <h3 aria-level="2" role="heading" id="h3_embedding-json-ld-in-html-documents"><span class="secno">6.20 </span>Embedding JSON-LD in HTML Documents</h3><p><em>This section is non-normative.</em></p>
+
+ <p>HTML script tags can be used to embed blocks of data in documents.
+ This way, JSON-LD content can be easily embedded in HTML by placing
+ it in a script element with the <code>type</code> attribute set to
+ <code>application/ld+json</code>.</p>
+
+ <div class="example"><div class="example-title"><span>Example 62</span>: Embedding JSON-LD in HTML</div><pre class="example"><span class="highlight"><script type="application/ld+json"></span>
+{
+ "@context": "http://json-ld.org/contexts/person.jsonld",
+ "@id": "http://dbpedia.org/resource/John_Lennon",
+ "name": "John Lennon",
+ "born": "1940-10-09",
+ "spouse": "http://dbpedia.org/resource/Cynthia_Lennon"
+}
+<span class="highlight"></script></span></pre></div>
+
+ <p>Depending on how the HTML document is served, certain strings may need
+ to be escaped.</p>
+
+ <p>Defining how such data may be used is beyond the scope of this specification.
+ The embedded JSON-LD document might be extracted as is or, e.g., be
+ interpreted as RDF.</p>
+
+ <p>If JSON-LD content is extracted as RDF [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>], it should be expanded into an
+ <a class="tref externalDFN" title="rdf-dataset" href="http://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset">RDF Dataset</a> using the
+ <cite><a href="../json-ld-api/#deserialize-json-ld-to-rdf-algorithm">Deserialize JSON-LD to RDF Algorithm</a></cite>
+ [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>].</p>
+</section>
+
+</section>
+
+<section class="normative" id="data-model">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_data-model"><span class="secno">7. </span>Data Model</h2>
+
+ <p>JSON-LD is a serialization format for Linked Data based on JSON.
+ It is therefore important to distinguish between the syntax, which is
+ defined by JSON in [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>], and the <dfn title="data-model" id="dfn-data-model">data model</dfn> which is
+ an extension of the RDF data model [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>]. The precise
+ details of how JSON-LD relates to the RDF data model are given in
+ <a class="sectionRef sec-ref" href="#relationship-to-rdf">section 9. Relationship to RDF</a>.</p>
+
+ <p>To ease understanding for developers unfamiliar with the RDF model, the
+ following summary is provided:</p>
+
+ <ul>
+ <li>A <dfn title="json-ld-document" id="dfn-json-ld-document">JSON-LD document</dfn> serializes a
+ <a href="http://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset" class="externalDFN">generalized RDF Dataset</a>
+ [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>], which is a collection of <a class="tref internalDFN" title="graph" href="#dfn-graph">graphs</a>
+ that comprises exactly one <dfn title="default-graph" id="dfn-default-graph"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-default-graph" class="externalDFN">default graph</a></dfn>
+ and zero or more <dfn title="named-graph" id="dfn-named-graph"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-named-graph" class="externalDFN">named graphs</a></dfn>.</li>
+ <li>The <a class="tref internalDFN" title="default-graph" href="#dfn-default-graph">default graph</a> does not have a name and <em class="rfc2119" title="MAY">MAY</em> be empty.</li>
+ <li>Each <a class="tref internalDFN" title="named-graph" href="#dfn-named-graph">named graph</a> is a pair consisting of an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or
+ <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a> (the
+ <dfn title="graph-name" id="dfn-graph-name"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-graph-name" class="externalDFN">graph name</a></dfn>)
+ and a <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a>. Whenever practical, the <a class="tref internalDFN" title="graph-name" href="#dfn-graph-name">graph name</a> <em class="rfc2119" title="SHOULD">SHOULD</em> be an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</li>
+ <li>A <dfn title="graph" id="dfn-graph"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-graph" class="externalDFN">graph</a></dfn>
+ is a labeled directed graph, i.e., a set of <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a>
+ connected by <a class="tref internalDFN" title="edge" href="#dfn-edge">edges</a>.</li>
+ <li>Every <dfn title="edge" id="dfn-edge">edge</dfn> has a direction associated with it and is labeled with
+ an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>. Within the JSON-LD syntax
+ these edge labels are called
+ <dfn title="property" id="dfn-property"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-property" class="externalDFN">properties</a></dfn>.
+ Whenever practical, an <a class="tref internalDFN" title="edge" href="#dfn-edge">edge</a> <em class="rfc2119" title="SHOULD">SHOULD</em> be labeled with an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</li>
+ <li>Every <dfn title="node" id="dfn-node"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-node" class="externalDFN">node</a></dfn>
+ is an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank node</a>, a <a class="tref internalDFN" title="json-ld-value" href="#dfn-json-ld-value">JSON-LD value</a>,
+ or a <a class="tref internalDFN" title="list" href="#dfn-list">list</a>.</li>
+ <li>A <a class="tref internalDFN" title="node" href="#dfn-node">node</a> having an outgoing edge <em class="rfc2119" title="MUST">MUST</em> be an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a
+ <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank node</a>.</li>
+ <li>A <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> contain unconnected <a class="tref internalDFN" title="node" href="#dfn-node">nodes</a>,
+ i.e., nodes which are not connected by an <a class="tref internalDFN" title="edge" href="#dfn-edge">edge</a> to any other <a class="tref internalDFN" title="node" href="#dfn-node">node</a>.</li>
+ <li>An <dfn title="iri" id="dfn-iri"><abbr title="Internationalized Resource Identifier"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-iri" class="externalDFN">IRI</a></abbr></dfn>
+ (Internationalized Resource Identifier) is a string that conforms to the syntax
+ defined in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>]. <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> used within a
+ <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a> <em class="rfc2119" title="SHOULD">SHOULD</em> return a Linked Data document describing
+ the resource denoted by that <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> when being dereferenced.</li>
+ <li>A <dfn title="blank-node" id="dfn-blank-node"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-blank-node" class="externalDFN">blank node</a></dfn>
+ is a <a class="tref internalDFN" title="node" href="#dfn-node">node</a> which is neither an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ nor a <a class="tref internalDFN" title="json-ld-value" href="#dfn-json-ld-value">JSON-LD value</a>, nor a <a class="tref internalDFN" title="list" href="#dfn-list">list</a>. A blank node <em class="rfc2119" title="MAY">MAY</em> be identified
+ using a <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>.</li>
+ <li>A <dfn title="blank-node-identifier" id="dfn-blank-node-identifier"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-blank-node-identifier" class="externalDFN">blank node identifier</a></dfn>
+ is a string that can be used as an identifier for a <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank node</a> within
+ the scope of a <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a>. Blank node identifiers begin with
+ <code>_:</code>.</li>
+ <li>A <dfn title="json-ld-value" id="dfn-json-ld-value">JSON-LD value</dfn> is a <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed value</a>, a <a class="tref internalDFN" title="string" href="#dfn-string">string</a> (which is interpreted
+ as <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed value</a> with type <code>xsd:string</code>), a <a class="tref internalDFN" title="number" href="#dfn-number">number</a>
+ (<a class="tref internalDFN" title="number" href="#dfn-number">numbers</a> with a non-zero fractional part, i.e., the result of a modulo‑1 operation,
+ are interpreted as <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed values</a> with type <code>xsd:double</code>, all other
+ <a class="tref internalDFN" title="number" href="#dfn-number">numbers</a> are interpreted as <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed values</a>
+ with type <code>xsd:integer</code>), <a class="tref internalDFN" title="true" href="#dfn-true">true</a> or <a class="tref internalDFN" title="false" href="#dfn-false">false</a> (which are interpreted as
+ <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed values</a> with type <code>xsd:boolean</code>),
+ or a <a class="tref internalDFN" title="language-tagged-string" href="#dfn-language-tagged-string">language-tagged string</a>.</li>
+ <li>A <dfn title="typed-value" id="dfn-typed-value">typed value</dfn> consists of a value, which is a string, and a type, which is an
+ <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</li>
+ <li>A <dfn title="language-tagged-string" id="dfn-language-tagged-string"><a href="http://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string" class="externalDFN">language-tagged string</a></dfn>
+ consists of a string and a non-empty language tag as defined by [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>].
+ The language tag <em class="rfc2119" title="MUST">MUST</em> be well-formed according to section
+ <a href="http://tools.ietf.org/html/bcp47#section-2.2.9">2.2.9 Classes of Conformance</a>
+ of [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>].</li>
+ <li>A <dfn title="list" id="dfn-list">list</dfn> is a sequence of zero or more <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>,
+ <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a>, and <a class="tref internalDFN" title="json-ld-value" href="#dfn-json-ld-value">JSON-LD values</a>.
+ <a class="tref internalDFN" title="list" href="#dfn-list">Lists</a> are interpreted as
+ <a href="http://www.w3.org/TR/rdf11-mt/#rdf-collections" class="externalDFN">RDF list structures</a> [<cite><a class="bibref" href="#bib-RDF11-MT">RDF11-MT</a></cite>].</li>
+ </ul>
+
+ <p><a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD documents</a> <em class="rfc2119" title="MAY">MAY</em> contain data
+ that cannot be represented by the <a class="tref internalDFN" title="data-model" href="#dfn-data-model">data model</a>
+ defined above. Unless otherwise specified, such data is ignored when a
+ <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a> is being processed. One result of this rule
+ is that properties which are not mapped to an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ a <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank node</a>, or <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> will be ignored.</p>
+
+ <p style="text-align: center"><img src="linked-data-graph.png" title="An illustration of the data model" alt="An illustration of the data model"></p>
+ <p style="text-align: center">Figure 1: An illustration of the data model.</p>
+</section>
+
+<section class="normative" id="json-ld-grammar">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_json-ld-grammar"><span class="secno">8. </span>JSON-LD Grammar</h2>
+
+ <p>This appendix restates the syntactic conventions described in the
+ previous sections more formally.</p>
+
+ <p>A <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a> <em class="rfc2119" title="MUST">MUST</em> be a valid JSON document as described
+ in [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>].</p>
+
+ <p>A <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a> <em class="rfc2119" title="MUST">MUST</em> be a single <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>
+ or an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> whose elements are each
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a> at the top level.</p>
+
+ <p>In contrast to JSON, in JSON-LD the keys in <a class="tref internalDFN" title="json-object" href="#dfn-json-object">objects</a>
+ <em class="rfc2119" title="MUST">MUST</em> be unique.</p>
+
+ <div class="note"><div class="note-title" aria-level="2" role="heading" id="h_note_9"><span>Note</span></div><p class="">JSON-LD allows <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> to be aliased
+ (see <a class="sectionRef sec-ref" href="#aliasing-keywords">section 6.15 Aliasing Keywords</a> for details). Whenever a <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> is
+ discussed in this grammar, the statements also apply to an alias for
+ that <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>. For example, if the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>
+ defines the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> <code>id</code> as an alias for <code>@id</code>,
+ that alias may be legitimately used as a substitution for <code>@id</code>.
+ Note that <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> aliases are not expanded during context
+ processing.</p></div>
+
+ <section class="normative" id="terms">
+ <h3 aria-level="2" role="heading" id="h3_terms"><span class="secno">8.1 </span>Terms</h3>
+
+ <p>A <dfn title="term" id="dfn-term">term</dfn> is a short-hand <a class="tref internalDFN" title="string" href="#dfn-string">string</a> that expands
+ to an <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>.</p>
+
+ <p>A <a class="tref internalDFN" title="term" href="#dfn-term">term</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> equal any of the JSON-LD
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a>.</p>
+
+ <p>To avoid forward-compatibility issues, a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> start
+ with an <code>@</code> character as future versions of JSON-LD may introduce
+ additional <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a>. Furthermore, the term <em class="rfc2119" title="MUST NOT">MUST NOT</em>
+ be an empty <a class="tref internalDFN" title="string" href="#dfn-string">string</a> (<code>""</code>) as not all programming languages
+ are able to handle empty JSON keys.</p>
+
+ <p>See <a class="sectionRef sec-ref" href="#the-context">section 5.1 The Context</a> and
+ <a class="sectionRef sec-ref" href="#iris">section 5.2 IRIs</a> for further discussion
+ on mapping <a class="tref internalDFN" title="term" href="#dfn-term">terms</a> to <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>.</p>
+ </section>
+
+ <section class="normative" id="node-objects">
+ <h3 aria-level="2" role="heading" id="h3_node-objects"><span class="secno">8.2 </span>Node Objects</h3>
+
+ <p>A <dfn title="node-object" id="dfn-node-object">node object</dfn> represents zero or more properties of a
+ <a class="tref internalDFN" title="node" href="#dfn-node">node</a> in the <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a> serialized by the
+ <a class="tref internalDFN" title="json-ld-document" href="#dfn-json-ld-document">JSON-LD document</a>. A <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> is a
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> if it exists outside of a JSON-LD
+ <a class="tref internalDFN" title="context" href="#dfn-context">context</a> and:</p>
+
+ <ul>
+ <li>it does not contain the <code>@value</code>, <code>@list</code>,
+ or <code>@set</code> keywords, and</li>
+ <li>it is not the top-most <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> in the JSON-LD document
+ consisting of no other members than <code>@graph</code> and
+ <code>@context</code>.</li>
+ </ul>
+
+ <p>The <a class="tref internalDFN" title="property" href="#dfn-property">properties</a> of a <a class="tref internalDFN" title="node" href="#dfn-node">node</a> in
+ a <a class="tref internalDFN" title="graph" href="#dfn-graph">graph</a> may be spread among different
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a> within a document. When
+ that happens, the keys of the different
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a> need to be merged to create the
+ properties of the resulting <a class="tref internalDFN" title="node" href="#dfn-node">node</a>.</p>
+
+ <p>A <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a>. All keys
+ which are not <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>,
+ <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact IRIs</a>, <a class="tref internalDFN" title="term" href="#dfn-term">terms</a>
+ valid in the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>, or one of the following
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> <em class="rfc2119" title="MUST">MUST</em> be ignored when processed:</p>
+
+ <ul>
+ <li><code>@context</code>,</li>
+ <li><code>@id</code>,</li>
+ <li><code>@graph</code>,</li>
+ <li><code>@type</code>,</li>
+ <li><code>@reverse</code>, or</li>
+ <li><code>@index</code></li>
+ </ul>
+
+ <p>If the <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> contains the <code>@context</code>
+ key, its value <em class="rfc2119" title="MUST">MUST</em> be <a class="tref internalDFN" title="null" href="#dfn-null">null</a>, an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ a <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="context-definition" href="#dfn-context-definition">context definition</a>, or
+ an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> composed of any of these.</p>
+
+ <p>If the <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> contains the <code>@id</code> key,
+ its value <em class="rfc2119" title="MUST">MUST</em> be an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ or a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (including
+ <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifiers</a>).
+ See <a class="sectionRef sec-ref" href="#node-identifiers">section 5.3 Node Identifiers</a>,
+ <a class="sectionRef sec-ref" href="#compact-iris">section 6.3 Compact IRIs</a>, and
+ <a class="sectionRef sec-ref" href="#identifying-blank-nodes">section 6.14 Identifying Blank Nodes</a> for further discussion on
+ <code>@id</code> values.</p>
+
+ <p>If the <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> contains the <code>@graph</code>
+ key, its value <em class="rfc2119" title="MUST">MUST</em> be
+ a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> or
+ an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> of zero or more <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a>.
+ If the <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> contains an <code>@id</code> keyword,
+ its value is used as the label of a named graph.
+ See <a class="sectionRef sec-ref" href="#named-graphs">section 6.13 Named Graphs</a> for further discussion on
+ <code>@graph</code> values. As a special case, if a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a>
+ contains no keys other than <code>@graph</code> and <code>@context</code>, and the
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> is the root of the JSON-LD document, the
+ <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> is not treated as a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>; this
+ is used as a way of defining <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node
+ definitions</a> that may not form a connected graph. This allows a
+ <a class="tref internalDFN" title="context" href="#dfn-context">context</a> to be defined which is shared by all of the constituent
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a>.</p>
+
+ <p>If the <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> contains the <code>@type</code>
+ key, its value <em class="rfc2119" title="MUST">MUST</em> be either an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a
+ <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ (including <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifiers</a>),
+ a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> defined in the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a> expanding into an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, or
+ an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> of any of these.
+ See <a class="sectionRef sec-ref" href="#specifying-the-type">section 5.4 Specifying the Type</a> for further discussion on
+ <code>@type</code> values.</p>
+
+ <p>If the <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> contains the <code>@reverse</code> key,
+ its value <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> containing members representing reverse
+ properties. Each value of such a reverse property <em class="rfc2119" title="MUST">MUST</em> be an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ a <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>,
+ a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> or an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> containing a combination of these.</p>
+
+ <p>If the <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> contains the <code>@index</code> key,
+ its value <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="string" href="#dfn-string">string</a>. See
+ <a class="sectionRef sec-ref" href="#data-indexing">section 6.16 Data Indexing</a> for further discussion
+ on <code>@index</code> values.</p>
+
+ <p>Keys in a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> that are not
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> <em class="rfc2119" title="MAY">MAY</em> expand to an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
+ using the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a>. The values associated with keys that expand
+ to an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> <em class="rfc2119" title="MUST">MUST</em> be one of the following:</p>
+
+ <ul>
+ <li><a class="tref internalDFN" title="string" href="#dfn-string">string</a>,</li>
+ <li><a class="tref internalDFN" title="number" href="#dfn-number">number</a>,</li>
+ <li><a class="tref internalDFN" title="true" href="#dfn-true">true</a>,</li>
+ <li><a class="tref internalDFN" title="false" href="#dfn-false">false</a>,</li>
+ <li><a class="tref internalDFN" title="null" href="#dfn-null">null</a>,</li>
+ <li><a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>,</li>
+ <li><a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a>,</li>
+ <li><a class="tref internalDFN" title="list-object" href="#dfn-list-object">list object</a>,</li>
+ <li><a class="tref internalDFN" title="set-object" href="#dfn-set-object">set object</a>,</li>
+ <li>an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> of zero or more of the possibilities above,</li>
+ <li>a <a class="tref internalDFN" title="language-map" href="#dfn-language-map">language map</a>, or </li>
+ <li>an <a class="tref internalDFN" title="index-map" href="#dfn-index-map">index map</a></li>
+ </ul>
+ </section>
+
+ <section class="normative" id="value-objects">
+ <h3 aria-level="2" role="heading" id="h3_value-objects"><span class="secno">8.3 </span>Value Objects</h3>
+
+ <p>A <dfn title="value-object" id="dfn-value-object">value object</dfn> is used to explicitly associate a type or a
+ language with a value to create a <a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed value</a> or a <a class="tref internalDFN" title="language-tagged-string" href="#dfn-language-tagged-string">language-tagged
+ string</a>.</p>
+
+ <p>A <a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a> <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> containing the
+ <code>@value</code> key. It <em class="rfc2119" title="MAY">MAY</em> also contain a <code>@type</code>,
+ a <code>@language</code>, an <code>@index</code>, or an <code>@context</code> key but <em class="rfc2119" title="MUST NOT">MUST NOT</em> contain
+ both a <code>@type</code> and a <code>@language</code> key at the same time.
+ A <a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> contain any other keys that expand to an
+ <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>.</p>
+
+ <p>The value associated with the <code>@value</code> key <em class="rfc2119" title="MUST">MUST</em> be either a
+ <a class="tref internalDFN" title="string" href="#dfn-string">string</a>, a <a class="tref internalDFN" title="number" href="#dfn-number">number</a>, <a class="tref internalDFN" title="true" href="#dfn-true">true</a>,
+ <a class="tref internalDFN" title="false" href="#dfn-false">false</a> or <a class="tref internalDFN" title="null" href="#dfn-null">null</a>.</p>
+
+ <p>The value associated with the <code>@type</code> key <em class="rfc2119" title="MUST">MUST</em> be a
+ <a class="tref internalDFN" title="term" href="#dfn-term">term</a>, a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, or <a class="tref internalDFN" title="null" href="#dfn-null">null</a>.</p>
+
+ <p>The value associated with the <code>@language</code> key <em class="rfc2119" title="MUST">MUST</em> have the
+ lexical form described in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>], or be <a class="tref internalDFN" title="null" href="#dfn-null">null</a>.</p>
+
+ <p>The value associated with the <code>@index</code> key <em class="rfc2119" title="MUST">MUST</em> be a
+ <a class="tref internalDFN" title="string" href="#dfn-string">string</a>.</p>
+
+ <p>See <a class="sectionRef sec-ref" href="#typed-values">section 6.4 Typed Values</a> and
+ <a class="sectionRef sec-ref" href="#string-internationalization">section 6.9 String Internationalization</a>
+ for more information on <a class="tref internalDFN" title="value-object" href="#dfn-value-object">value objects</a>.</p>
+ </section>
+
+ <section class="normative" id="lists-and-sets">
+ <h3 aria-level="2" role="heading" id="h3_lists-and-sets"><span class="secno">8.4 </span>Lists and Sets</h3>
+
+ <p>A <a class="tref internalDFN" title="list" href="#dfn-list">list</a> represents an <em>ordered</em> set of values. A set
+ represents an <em>unordered</em> set of values. Unless otherwise specified,
+ <a class="tref internalDFN" title="array" href="#dfn-array">arrays</a> are unordered in JSON-LD. As such, the
+ <code>@set</code> keyword, when used in the body of a JSON-LD document,
+ represents just syntactic sugar which is optimized away when processing the document.
+ However, it is very helpful when used within the context of a document. Values
+ of terms associated with a <code>@set</code> or <code>@list</code> container
+ will always be represented in the form of an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> when a document
+ is processed—even if there is just a single value that would otherwise be optimized to
+ a non-array form in <a href="#compacted-document-form">compact document form</a>.
+ This simplifies post-processing of the data as the data is always in a
+ deterministic form.</p>
+
+ <p>A <dfn title="list-object" id="dfn-list-object">list object</dfn> <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> that contains no
+ keys that expand to an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> other
+ than <code>@list</code>, <code>@context</code>, and <code>@index</code>.</p>
+
+ <p>A <dfn title="set-object" id="dfn-set-object">set object</dfn> <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> that contains no
+ keys that expand to an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a> other
+ than <code>@list</code>, <code>@context</code>, and <code>@index</code>.
+ Please note that the <code>@index</code> key will be ignored when being processed.</p>
+
+ <p>In both cases, the value associated with the keys <code>@list</code> and <code>@set</code>
+ <em class="rfc2119" title="MUST">MUST</em> be one of the following types:</p>
+ <ul>
+ <li><a class="tref internalDFN" title="string" href="#dfn-string">string</a>,</li>
+ <li><a class="tref internalDFN" title="number" href="#dfn-number">number</a>,</li>
+ <li><a class="tref internalDFN" title="true" href="#dfn-true">true</a>,</li>
+ <li><a class="tref internalDFN" title="false" href="#dfn-false">false</a>,</li>
+ <li><a class="tref internalDFN" title="null" href="#dfn-null">null</a>,</li>
+ <li><a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>,</li>
+ <li><a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a>, or</li>
+ <li>an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> of zero or more of the above possibilities</li>
+ </ul>
+
+ <p>See <a class="sectionRef sec-ref" href="#sets-and-lists">section 6.11 Sets and Lists</a> for further discussion on sets and lists.</p>
+ </section>
+
+ <section class="normative" id="language-maps">
+ <h3 aria-level="2" role="heading" id="h3_language-maps"><span class="secno">8.5 </span>Language Maps</h3>
+
+ <p>A <dfn title="language-map" id="dfn-language-map">language map</dfn> is used to associate a language with a value in a
+ way that allows easy programmatic access. A <a class="tref internalDFN" title="language-map" href="#dfn-language-map">language map</a> may be
+ used as a term value within a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> if the term is defined
+ with <code>@container</code> set to <code>@language</code>. The keys of a
+ <a class="tref internalDFN" title="language-map" href="#dfn-language-map">language map</a> <em class="rfc2119" title="MUST">MUST</em> be <a class="tref internalDFN" title="string" href="#dfn-string">strings</a> representing
+ [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] language codes and the values <em class="rfc2119" title="MUST">MUST</em> be any of the following types:</p>
+
+ <ul>
+ <li><a class="tref internalDFN" title="null" href="#dfn-null">null</a>,</li>
+ <li><a class="tref internalDFN" title="string" href="#dfn-string">string</a>, or</li>
+ <li>an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> of zero or more of the above possibilities</li>
+ </ul>
+
+ <p>See <a class="sectionRef sec-ref" href="#string-internationalization">section 6.9 String Internationalization</a> for further discussion
+ on language maps.</p>
+ </section>
+
+ <section class="normative" id="index-maps">
+ <h3 aria-level="2" role="heading" id="h3_index-maps"><span class="secno">8.6 </span>Index Maps</h3>
+
+ <p>An <dfn title="index-map" id="dfn-index-map">index map</dfn> allows keys that have no semantic meaning,
+ but should be preserved regardless, to be used in JSON-LD documents.
+ An <a class="tref internalDFN" title="index-map" href="#dfn-index-map">index map</a> may
+ be used as a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> value within a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> if the
+ term is defined with <code>@container</code> set to <code>@index</code>.
+ The values of the members of an <a class="tref internalDFN" title="index-map" href="#dfn-index-map">index map</a> <em class="rfc2119" title="MUST">MUST</em> be one
+ of the following types:</p>
+
+ <ul>
+ <li><a class="tref internalDFN" title="string" href="#dfn-string">string</a>,</li>
+ <li><a class="tref internalDFN" title="number" href="#dfn-number">number</a>,</li>
+ <li><a class="tref internalDFN" title="true" href="#dfn-true">true</a>,</li>
+ <li><a class="tref internalDFN" title="false" href="#dfn-false">false</a>,</li>
+ <li><a class="tref internalDFN" title="null" href="#dfn-null">null</a>,</li>
+ <li><a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>,</li>
+ <li><a class="tref internalDFN" title="value-object" href="#dfn-value-object">value object</a>,</li>
+ <li><a class="tref internalDFN" title="list-object" href="#dfn-list-object">list object</a>,</li>
+ <li><a class="tref internalDFN" title="set-object" href="#dfn-set-object">set object</a>,</li>
+ <li>an <a class="tref internalDFN" title="array" href="#dfn-array">array</a> of zero or more of the above possibilities</li>
+ </ul>
+
+ <p>See <a class="sectionRef sec-ref" href="#data-indexing">section 6.16 Data Indexing</a> for further information on this topic.</p>
+ </section>
+
+<section class="normative" id="context-definitions">
+ <h3 aria-level="2" role="heading" id="h3_context-definitions"><span class="secno">8.7 </span>Context Definitions</h3>
+
+ <p>A <dfn title="context-definition" id="dfn-context-definition">context definition</dfn> defines a <a class="tref internalDFN" title="local-context" href="#dfn-local-context">local context</a> in a
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>.</p>
+
+ <p>A <a class="tref internalDFN" title="context-definition" href="#dfn-context-definition">context definition</a> <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a> whose
+ keys <em class="rfc2119" title="MUST">MUST</em> either be <a class="tref internalDFN" title="term" href="#dfn-term">terms</a>,
+ <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact IRIs</a>, <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute IRIs</a>,
+ or the <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> <code>@language</code>, <code>@base</code>,
+ and <code>@vocab</code>.</p>
+
+ <p>If the <a class="tref internalDFN" title="context-definition" href="#dfn-context-definition">context definition</a> has a <code>@language</code> key,
+ its value <em class="rfc2119" title="MUST">MUST</em> have the lexical form described in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] or be <a class="tref internalDFN" title="null" href="#dfn-null">null</a>.</p>
+
+ <p>If the <a class="tref internalDFN" title="context-definition" href="#dfn-context-definition">context definition</a> has a <code>@base</code> key,
+ its value <em class="rfc2119" title="MUST">MUST</em> be an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="relative-iri" href="#dfn-relative-iri">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ or <a class="tref internalDFN" title="null" href="#dfn-null">null</a>.</p>
+
+ <p>If the <a class="tref internalDFN" title="context-definition" href="#dfn-context-definition">context definition</a> has a <code>@vocab</code> key,
+ its value <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ a <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>, a <a class="tref internalDFN" title="term" href="#dfn-term">term</a>, or <a class="tref internalDFN" title="null" href="#dfn-null">null</a>.</p>
+
+ <p>The value of keys that are not <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> <em class="rfc2119" title="MUST">MUST</em> be either an
+ <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="term" href="#dfn-term">term</a>,
+ a <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>, a <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>, <a class="tref internalDFN" title="null" href="#dfn-null">null</a>,
+ or an <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a>.</p>
+
+ <p>An <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> is used to describe the mapping
+ between a <a class="tref internalDFN" title="term" href="#dfn-term">term</a> and its expanded identifier, as well as other
+ properties of the value associated with the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> when it is
+ used as key in a <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>.</p>
+
+ <p>An <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="json-object" href="#dfn-json-object">JSON object</a>
+ composed of zero or more keys from <code>@id</code>, <code>@reverse</code>,
+ <code>@type</code>, <code>@language</code> or <code>@container</code>. An
+ <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> contain any other keys.</p>
+
+ <p>If an <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> has an <code>@reverse</code> member,
+ it <em class="rfc2119" title="MUST NOT">MUST NOT</em> have an <code>@id</code> member at the same time. If an
+ <code>@container</code> member exists, its value <em class="rfc2119" title="MUST">MUST</em> be <a class="tref internalDFN" title="null" href="#dfn-null">null</a>,
+ <code>@set</code>, or <code>@index</code>.</p>
+
+ <p>If the term being defined is not a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or
+ <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> and the <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a> does not have an
+ <code>@vocab</code> mapping, the <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> <em class="rfc2119" title="MUST">MUST</em>
+ include the <code>@id</code> key.</p>
+
+ <p>If the <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> contains the <code>@id</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be <a class="tref internalDFN" title="null" href="#dfn-null">null</a>, an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
+ a <a class="tref internalDFN" title="blank-node-identifier" href="#dfn-blank-node-identifier">blank node identifier</a>, a <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="term" href="#dfn-term">term</a>,
+ or a <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>.</p>
+
+ <p>If the <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> contains the <code>@type</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be an <a class="tref internalDFN" title="absolute-iri" href="#dfn-absolute-iri">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a
+ <a class="tref internalDFN" title="compact-iri" href="#dfn-compact-iri">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a class="tref internalDFN" title="term" href="#dfn-term">term</a>, <a class="tref internalDFN" title="null" href="#dfn-null">null</a>, or the one of the
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keywords</a> <code>@id</code> or <code>@vocab</code>.</p>
+
+ <p>If the <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> contains the <code>@language</code> <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>,
+ its value <em class="rfc2119" title="MUST">MUST</em> have the lexical form described in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] or be <a class="tref internalDFN" title="null" href="#dfn-null">null</a>.</p>
+
+ <p>If the <a class="tref internalDFN" title="expanded-term-definition" href="#dfn-expanded-term-definition">expanded term definition</a> contains the <code>@container</code>
+ <a class="tref internalDFN" title="keyword" href="#dfn-keyword">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be either <code>@list</code>, <code>@set</code>,
+ <code>@language</code>, <code>@index</code>, or be <a class="tref internalDFN" title="null" href="#dfn-null">null</a>. If the value
+ is <code>@language</code>, when the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is used outside of the
+ <code>@context</code>, the associated value <em class="rfc2119" title="MUST">MUST</em> be a <a class="tref internalDFN" title="language-map" href="#dfn-language-map">language map</a>.
+ If the value is <code>@index</code>, when the <a class="tref internalDFN" title="term" href="#dfn-term">term</a> is used outside of
+ the <code>@context</code>, the associated value <em class="rfc2119" title="MUST">MUST</em> be an
+ <a class="tref internalDFN" title="index-map" href="#dfn-index-map">index map</a>.</p>
+
+ <p><a class="tref internalDFN" title="term" href="#dfn-term">Terms</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> be used in a circular manner. That is,
+ the definition of a term cannot depend on the definition of another term if that other
+ term also depends on the first term.</p>
+
+ <p>See <a class="sectionRef sec-ref" href="#the-context">section 5.1 The Context</a> for further discussion on contexts.</p>
+</section>
+
+</section>
+
+<section class="normative" id="relationship-to-rdf">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_relationship-to-rdf"><span class="secno">9. </span>Relationship to RDF</h2>
+
+ <p>JSON-LD is a
+ <a class="tref externalDFN" title="concrete-rdf-syntax" href="http://www.w3.org/TR/rdf11-concepts/#dfn-concrete-rdf-syntax">concrete RDF syntax</a>
+ as described in [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>]. Hence, a JSON-LD document is both an
+ RDF document <em>and</em> a JSON document and correspondingly represents an
+ instance of an RDF data model. However, JSON-LD also extends the RDF data
+ model to optionally allow JSON-LD to serialize
+ <a class="tref externalDFN" title="generalized-rdf-datasets" href="http://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">Generalized RDF Datasets</a>.
+ The JSON-LD extensions to the RDF data model are:</p>
+
+ <ul>
+ <li>In JSON-LD <a class="tref internalDFN" title="property" href="#dfn-property">properties</a> can be
+ <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> or <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a>
+ whereas in RDF properties (predicates) have to be <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>. This
+ means that JSON-LD serializes
+ <a class="tref externalDFN" title="generalized-rdf-datasets" href="http://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Datasets</a>.</li>
+ <li>In JSON-LD <a class="tref internalDFN" title="list" href="#dfn-list">lists</a> are part of the data model
+ whereas in RDF they are part of a vocabulary, namely [<cite><a class="bibref" href="#bib-RDF-SCHEMA">RDF-SCHEMA</a></cite>].</li>
+ <li>RDF values are either typed <em>literals</em>
+ (<a class="tref internalDFN" title="typed-value" href="#dfn-typed-value">typed values</a>) or <em>language-tagged strings</em>
+ (<a class="tref internalDFN" title="language-tagged-string" href="#dfn-language-tagged-string">language-tagged strings</a>) whereas
+ JSON-LD also supports JSON's native data types, i.e., <a class="tref internalDFN" title="number" href="#dfn-number">number</a>,
+ <a class="tref internalDFN" title="string" href="#dfn-string">strings</a>, and the boolean values <a class="tref internalDFN" title="true" href="#dfn-true">true</a>
+ and <a class="tref internalDFN" title="false" href="#dfn-false">false</a>. The JSON-LD Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>]
+ defines the <a href="../json-ld-api/#data-round-tripping">conversion rules</a>
+ between JSON's native data types and RDF's counterparts to allow round-tripping.</li>
+ </ul>
+
+ <p>Summarized, these differences mean that JSON-LD is capable of serializing any RDF
+ graph or dataset and most, but not all, JSON-LD documents can be directly
+ interpreted as RDF as described in RDF 1.1 Concepts [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</p>
+
+ <p>For authors and developers working with <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a>
+ as <a class="tref internalDFN" title="property" href="#dfn-property">properties</a> when deserializing to RDF,
+ three potential approaches are suggested:</p>
+
+ <ul>
+ <li>If the author is not yet ready to commit to a stable <abbr title="Internationalized Resource Identifier">IRI</abbr>, the
+ property should be mapped to an <abbr title="Internationalized Resource Identifier">IRI</abbr> that is documented as unstable.</li>
+ <li>If the developer wishes to use <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a>
+ as <a class="tref internalDFN" title="property" href="#dfn-property">properties</a> and also wishes to interpret the
+ data as a
+ <a class="tref externalDFN" title="generalized-rdf-dataset" href="http://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Dataset</a>,
+ there is an option, <i>produce generalized RDF</i>, in the
+ Deserialize JSON-LD to RDF algorithm [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>] to do so. Note that a
+ <a class="tref externalDFN" title="generalized-rdf-dataset" href="http://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Dataset</a>
+ is an extension of RDF; it does not conform to the RDF standard.</li>
+ <li>If the author or developer wishes to use <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a>
+ as <a class="tref internalDFN" title="property" href="#dfn-property">properties</a> and wishes to interpret the data
+ as a standard (non-generalized)
+ <a class="tref externalDFN" title="rdf-dataset" href="http://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset">RDF Dataset</a>,
+ it is possible to losslessly interpret JSON-LD as RDF by transforming
+ <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a> used as
+ <a class="tref internalDFN" title="property" href="#dfn-property">properties</a> to <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a>,
+ by minting new "Skolem IRIs" as per
+ <cite><a href="http://www.w3.org/TR/rdf11-concepts/#section-skolemization">Replacing Blank Nodes with IRIs</a></cite>
+ of [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</li>
+ </ul>
+
+ <p>The normative algorithms for interpreting JSON-LD as RDF and serializing
+ RDF as JSON-LD are specified in the JSON-LD Processing Algorithms and API
+ specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>].</p>
+
+ <p>Even though JSON-LD serializes
+ <a class="tref externalDFN" title="generalized-rdf-datasets" href="http://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Datasets</a>, it can
+ also be used as a <a class="tref externalDFN" title="rdf-graph-source" href="http://www.w3.org/TR/rdf11-concepts/#dfn-rdf-source">RDF graph source</a>.
+ In that case, a consumer <em class="rfc2119" title="MUST">MUST</em> only use the default graph and ignore all named graphs.
+ This allows servers to expose data in languages such as Turtle and JSON-LD
+ using content negotiation.</p>
+
+ <div class="note"><div class="note-title" aria-level="2" role="heading" id="h_note_10"><span>Note</span></div><p class="">Publishers supporting both dataset and graph syntaxes have to ensure that
+ the primary data is stored in the default graph to enable consumers that do not support
+ datasets to process the information.</p></div>
+
+ <section class="informative" id="serializing-deserializing-rdf">
+ <h3 aria-level="2" role="heading" id="h3_serializing-deserializing-rdf"><span class="secno">9.1 </span>Serializing/Deserializing RDF</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The process of serializing RDF as JSON-LD and deserializing JSON-LD to RDF
+ depends on executing the algorithms defined in
+ <cite><a href="../json-ld-api/#rdf-serialization-deserialization-algorithms">RDF Serialization-Deserialization Algorithms</a></cite>
+ in the JSON-LD Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>].
+ It is beyond the scope of this document to detail these algorithms any further,
+ but a summary of the necessary operations is provided to illustrate the process.</p>
+
+ <p>The procedure to deserialize a JSON-LD document to RDF involves the
+ following steps:</p>
+
+ <ol>
+ <li>Expand the JSON-LD document, removing any context; this ensures
+ that properties, types, and values are given their full representation
+ as <a class="tref internalDFN" title="iri" href="#dfn-iri">IRIs</a> and expanded values. Expansion
+ is discussed further in <a class="sectionRef sec-ref" href="#expanded-document-form">section 6.17 Expanded Document Form</a>.</li>
+ <li>Flatten the document, which turns the document into an array of
+ <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node objects</a>. Flattening is discussed
+ further in <a class="sectionRef sec-ref" href="#flattened-document-form">section 6.19 Flattened Document Form</a>.</li>
+ <li>Turn each <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> into a series of
+ <a class="tref externalDFN" title="rdf-triples" href="http://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple">RDF triples</a>.</li>
+ </ol>
+
+ <p>For example, consider the following JSON-LD document in compact form:</p>
+
+ <div class="example"><div class="example-title"><span>Example 63</span>: Sample JSON-LD document</div><pre class="example">{
+ "@context": {
+ "name": "http://xmlns.com/foaf/0.1/name",
+ "knows": "http://xmlns.com/foaf/0.1/knows"
+ },
+ "@id": "http://me.markus-lanthaler.com/",
+ "name": "Markus Lanthaler",
+ "knows": [
+ {
+ "@id": "http://manu.sporny.org/about#manu",
+ "name": "Manu Sporny"
+ },
+ {
+ "name": "Dave Longley"
+ }
+ ]
+}</pre></div>
+
+ <p>Running the JSON-LD Expansion and Flattening algorithms against the
+ JSON-LD input document in the example above would result in the
+ following output:</p>
+
+ <div class="example"><div class="example-title"><span>Example 64</span>: Flattened and expanded form for the previous example</div><pre class="example">[
+ {
+ "@id": "_:b0",
+ "http://xmlns.com/foaf/0.1/name": "Dave Longley"
+ },
+ {
+ "@id": "http://manu.sporny.org/about#manu",
+ "http://xmlns.com/foaf/0.1/name": "Manu Sporny"
+ },
+ {
+ "@id": "http://me.markus-lanthaler.com/",
+ "http://xmlns.com/foaf/0.1/name": "Markus Lanthaler",
+ "http://xmlns.com/foaf/0.1/knows": [
+ { "@id": "http://manu.sporny.org/about#manu" },
+ { "@id": "_:b0" }
+ ]
+ }
+]</pre></div>
+
+ <p>Deserializing this to RDF now is a straightforward process of turning
+ each <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a> into one or more RDF triples. This can be
+ expressed in Turtle as follows:</p>
+
+ <div class="example"><div class="example-title"><span>Example 65</span>: Turtle representation of expanded/flattened document</div><pre class="example">_:b0 <http://xmlns.com/foaf/0.1/name> "Dave Longley" .
+
+<http://manu.sporny.org/about#manu> <http://xmlns.com/foaf/0.1/name> "Manu Sporny" .
+
+<http://me.markus-lanthaler.com/> <http://xmlns.com/foaf/0.1/name> "Markus Lanthaler" ;
+ <http://xmlns.com/foaf/0.1/knows> <http://manu.sporny.org/about#manu>, _:b0 .</pre></div>
+
+ <p>The process of serializing RDF as JSON-LD can be thought of as the
+ inverse of this last step, creating an expanded JSON-LD document closely
+ matching the triples from RDF, using a single <a class="tref internalDFN" title="node-object" href="#dfn-node-object">node object</a>
+ for all triples having a common subject, and a single <a class="tref internalDFN" title="property" href="#dfn-property">property</a>
+ for those triples also having a common predicate.</p>
+ </section>
+</section>
+
+<section class="appendix informative" id="relationship-to-other-linked-data-formats">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_relationship-to-other-linked-data-formats"><span class="secno">A. </span>Relationship to Other Linked Data Formats</h2><p><em>This section is non-normative.</em></p>
+
+ <p>The JSON-LD examples below demonstrate how JSON-LD can be used to
+ express semantic data marked up in other linked data formats such as Turtle,
+ RDFa, Microformats, and Microdata. These sections are merely provided as
+ evidence that JSON-LD is very flexible in what it can express across different
+ Linked Data approaches.</p>
+
+ <section class="informative" id="turtle">
+ <h3 aria-level="2" role="heading" id="h3_turtle"><span class="secno">A.1 </span>Turtle</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The following are examples of transforming RDF expressed in Turtle [<cite><a class="bibref" href="#bib-TURTLE">TURTLE</a></cite>]
+ into JSON-LD.</p>
+
+ <section>
+ <h4 id="prefix-definitions" aria-level="3" role="heading">Prefix definitions</h4><p><em>This section is non-normative.</em></p>
+
+ <p>The JSON-LD context has direct equivalents for the Turtle
+ <code>@prefix</code> declaration:</p>
+
+ <div class="example"><div class="example-title"><span>Example 66</span>: A set of statements serialized in Turtle</div><pre class="example">@prefix foaf: <http://xmlns.com/foaf/0.1/> .
+
+<http://manu.sporny.org/about#manu> a foaf:Person;
+ foaf:name "Manu Sporny";
+ foaf:homepage <http://manu.sporny.org/> .</pre></div>
+
+ <div class="example"><div class="example-title"><span>Example 67</span>: The same set of statements serialized in JSON-LD</div><pre class="example">{
+ "@context":
+ {
+ "foaf": "http://xmlns.com/foaf/0.1/"
+ },
+ "@id": "http://manu.sporny.org/about#manu",
+ "@type": "foaf:Person",
+ "foaf:name": "Manu Sporny",
+ "foaf:homepage": { "@id": "http://manu.sporny.org/" }
+}</pre></div>
+ </section>
+
+ <section>
+ <h4 id="embedding-1" aria-level="3" role="heading">Embedding</h4>
+
+ <p>Both Turtle and JSON-LD allow embedding, although Turtle only allows embedding of
+ <a class="tref internalDFN" title="blank-node" href="#dfn-blank-node">blank nodes</a>.</p>
+
+ <div class="example"><div class="example-title"><span>Example 68</span>: Embedding in Turtle</div><pre class="example">@prefix foaf: <http://xmlns.com/foaf/0.1/> .
+
+<http://manu.sporny.org/about#manu>
+ a foaf:Person;
+ foaf:name "Manu Sporny";
+ foaf:knows [ a foaf:Person; foaf:name "Gregg Kellogg" ] .</pre></div>
+
+ <div class="example"><div class="example-title"><span>Example 69</span>: Same embedding example in JSON-LD</div><pre class="example">{
+ "@context":
+ {
+ "foaf": "http://xmlns.com/foaf/0.1/"
+ },
+ "@id": "http://manu.sporny.org/about#manu",
+ "@type": "foaf:Person",
+ "foaf:name": "Manu Sporny",
+ "foaf:knows":
+ {
+ "@type": "foaf:Person",
+ "foaf:name": "Gregg Kellogg"
+ }
+}</pre></div>
+ </section>
+
+ <section>
+ <h4 id="conversion-of-native-data-types" aria-level="3" role="heading">Conversion of native data types</h4>
+
+ <p>In JSON-LD numbers and boolean values are native data types. While Turtle
+ has a shorthand syntax to express such values, RDF's abstract syntax requires
+ that numbers and boolean values are represented as typed literals. Thus,
+ to allow full round-tripping, the JSON-LD Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>]
+ defines conversion rules between JSON-LD's native data types and RDF's
+ counterparts. <a class="tref internalDFN" title="number" href="#dfn-number">Numbers</a> without fractions are
+ converted to <code>xsd:integer</code>-typed literals, numbers with fractions
+ to <code>xsd:double</code>-typed literals and the two boolean values
+ <a class="tref internalDFN" title="true" href="#dfn-true">true</a> and <a class="tref internalDFN" title="false" href="#dfn-false">false</a> to a <code>xsd:boolean</code>-typed
+ literal. All typed literals are in canonical lexical form.</p>
+
+ <div class="example"><div class="example-title"><span>Example 70</span>: JSON-LD using native data types for numbers and boolean values</div><pre class="example">{
+ "@context":
+ {
+ "ex": "http://example.com/vocab#"
+ },
+ "@id": "http://example.com/",
+ "ex:numbers": [ 14, 2.78 ],
+ "ex:booleans": [ true, false ]
+}</pre></div>
+
+ <div class="example"><div class="example-title"><span>Example 71</span>: Same example in Turtle using typed literals</div><pre class="example">@prefix ex: <http://example.com/vocab#> .
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+
+<http://example.com/>
+ ex:numbers "14"^^xsd:integer, "2.78E0"^^xsd:double ;
+ ex:booleans "true"^^xsd:boolean, "false"^^xsd:boolean .</pre></div>
+
+ </section>
+
+ <section>
+ <h4 id="lists" aria-level="3" role="heading">Lists</h4>
+ <p>Both JSON-LD and Turtle can represent sequential lists of values.</p>
+
+ <div class="example"><div class="example-title"><span>Example 72</span>: A list of values in Turtle</div><pre class="example">@prefix foaf: <http://xmlns.com/foaf/0.1/> .
+
+<http://example.org/people#joebob> a foaf:Person;
+ foaf:name "Joe Bob";
+ foaf:nick ( "joe" "bob" "jaybee" ) .</pre></div>
+
+ <div class="example"><div class="example-title"><span>Example 73</span>: Same example with a list of values in JSON-LD</div><pre class="example">{
+ "@context":
+ {
+ "foaf": "http://xmlns.com/foaf/0.1/"
+ },
+ "@id": "http://example.org/people#joebob",
+ "@type": "foaf:Person",
+ "foaf:name": "Joe Bob",
+ "foaf:nick":
+ {
+ "@list": [ "joe", "bob", "jaybee" ]
+ }
+}</pre></div>
+ </section>
+ </section>
+
+ <section class="informative" id="rdfa">
+ <h3 aria-level="2" role="heading" id="h3_rdfa"><span class="secno">A.2 </span>RDFa</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The following example describes three people with their respective names and
+ homepages in RDFa [<cite><a class="bibref" href="#bib-RDFA-CORE">RDFA-CORE</a></cite>].</p>
+
+ <div class="example"><div class="example-title"><span>Example 74</span>: RDFa fragment that describes three people</div><pre class="example"><div <span class="highlight">prefix="foaf: http://xmlns.com/foaf/0.1/"</span>>
+ <ul>
+ <li <span class="highlight">typeof="foaf:Person"</span>>
+ <a <span class="highlight">rel="foaf:homepage" href="http://example.com/bob/" property="foaf:name"</span>>Bob</a>
+ </li>
+ <li <span class="highlight">typeof="foaf:Person"</span>>
+ <a <span class="highlight">rel="foaf:homepage" href="http://example.com/eve/" property="foaf:name"</span>>Eve</a>
+ </li>
+ <li <span class="highlight">typeof="foaf:Person"</span>>
+ <a <span class="highlight">rel="foaf:homepage" href="http://example.com/manu/" property="foaf:name"</span>>Manu</a>
+ </li>
+ </ul>
+</div></pre></div>
+
+ <p>An example JSON-LD implementation using a single <a class="tref internalDFN" title="context" href="#dfn-context">context</a> is
+ described below.</p>
+
+ <div class="example"><div class="example-title"><span>Example 75</span>: Same description in JSON-LD (context shared among node objects)</div><pre class="example">{
+ "@context":
+ {
+ "foaf": "http://xmlns.com/foaf/0.1/"
+ },
+ "@graph":
+ [
+ {
+ "@type": "foaf:Person",
+ "foaf:homepage": "http://example.com/bob/",
+ "foaf:name": "Bob"
+ },
+ {
+ "@type": "foaf:Person",
+ "foaf:homepage": "http://example.com/eve/",
+ "foaf:name": "Eve"
+ },
+ {
+ "@type": "foaf:Person",
+ "foaf:homepage": "http://example.com/manu/",
+ "foaf:name": "Manu"
+ }
+ ]
+}</pre></div>
+ </section>
+
+ <section class="informative" id="microformats">
+ <h3 aria-level="2" role="heading" id="h3_microformats"><span class="secno">A.3 </span>Microformats</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The following example uses a simple Microformats hCard example to express
+ how Microformats [<cite><a class="bibref" href="#bib-MICROFORMATS">MICROFORMATS</a></cite>] are represented in JSON-LD.</p>
+
+ <div class="example"><div class="example-title"><span>Example 76</span>: HTML fragment with a simple Microformats hCard</div><pre class="example"><div class="vcard">
+ <a class="url fn" href="http://tantek.com/">Tantek Çelik</a>
+</div></pre></div>
+
+ <p>The representation of the hCard expresses the Microformat terms in the
+ <a class="tref internalDFN" title="context" href="#dfn-context">context</a> and uses them directly for the <code>url</code> and <code>fn</code>
+ properties. Also note that the Microformat to JSON-LD processor has
+ generated the proper URL type for <code>http://tantek.com/</code>.</p>
+
+ <div class="example"><div class="example-title"><span>Example 77</span>: Same hCard representation in JSON-LD</div><pre class="example">{
+ "@context":
+ {
+ "vcard": "http://microformats.org/profile/hcard#vcard",
+ "url":
+ {
+ "@id": "http://microformats.org/profile/hcard#url",
+ "@type": "@id"
+ },
+ "fn": "http://microformats.org/profile/hcard#fn"
+ },
+ "@type": "vcard",
+ "url": "http://tantek.com/",
+ "fn": "Tantek Çelik"
+}</pre></div>
+ </section>
+
+ <section class="informative" id="microdata">
+ <h3 aria-level="2" role="heading" id="h3_microdata"><span class="secno">A.4 </span>Microdata</h3><p><em>This section is non-normative.</em></p>
+
+ <p>The HTML Microdata [<cite><a class="bibref" href="#bib-MICRODATA">MICRODATA</a></cite>] example below expresses book information as
+ a Microdata Work item.</p>
+
+ <div class="example"><div class="example-title"><span>Example 78</span>: HTML fragments that describes a book using microdata</div><pre class="example"><dl itemscope
+ itemtype="http://purl.org/vocab/frbr/core#Work"
+ itemid="http://purl.oreilly.com/works/45U8QJGZSQKDH8N">
+ <dt>Title</dt>
+ <dd><cite itemprop="http://purl.org/dc/terms/title">Just a Geek</cite></dd>
+ <dt>By</dt>
+ <dd><span itemprop="http://purl.org/dc/terms/creator">Wil Wheaton</span></dd>
+ <dt>Format</dt>
+ <dd itemprop="http://purl.org/vocab/frbr/core#realization"
+ itemscope
+ itemtype="http://purl.org/vocab/frbr/core#Expression"
+ itemid="http://purl.oreilly.com/products/9780596007683.BOOK">
+ <link itemprop="http://purl.org/dc/terms/type" href="http://purl.oreilly.com/product-types/BOOK">
+ Print
+ </dd>
+ <dd itemprop="http://purl.org/vocab/frbr/core#realization"
+ itemscope
+ itemtype="http://purl.org/vocab/frbr/core#Expression"
+ itemid="http://purl.oreilly.com/products/9780596802189.EBOOK">
+ <link itemprop="http://purl.org/dc/terms/type" href="http://purl.oreilly.com/product-types/EBOOK">
+ Ebook
+ </dd>
+</dl></pre></div>
+
+ <p>Note that the JSON-LD representation of the Microdata information stays
+ true to the desires of the Microdata community to avoid contexts and
+ instead refer to items by their full <a class="tref internalDFN" title="iri" href="#dfn-iri"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
+
+ <div class="example"><div class="example-title"><span>Example 79</span>: Same book description in JSON-LD (avoiding contexts)</div><pre class="example">[
+ {
+ "@id": "http://purl.oreilly.com/works/45U8QJGZSQKDH8N",
+ "@type": "http://purl.org/vocab/frbr/core#Work",
+ "http://purl.org/dc/terms/title": "Just a Geek",
+ "http://purl.org/dc/terms/creator": "Whil Wheaton",
+ "http://purl.org/vocab/frbr/core#realization":
+ [
+ "http://purl.oreilly.com/products/9780596007683.BOOK",
+ "http://purl.oreilly.com/products/9780596802189.EBOOK"
+ ]
+ },
+ {
+ "@id": "http://purl.oreilly.com/products/9780596007683.BOOK",
+ "@type": "http://purl.org/vocab/frbr/core#Expression",
+ "http://purl.org/dc/terms/type": "http://purl.oreilly.com/product-types/BOOK"
+ },
+ {
+ "@id": "http://purl.oreilly.com/products/9780596802189.EBOOK",
+ "@type": "http://purl.org/vocab/frbr/core#Expression",
+ "http://purl.org/dc/terms/type": "http://purl.oreilly.com/product-types/EBOOK"
+ }
+]</pre></div>
+ </section>
+</section>
+
+<section class="appendix normative" id="iana-considerations">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_iana-considerations"><span class="secno">B. </span>IANA Considerations</h2>
+
+ <p>This section has been submitted to the Internet Engineering Steering
+ Group (IESG) for review, approval, and registration with IANA.</p>
+
+ <h2 id="application-ld-json">application/ld+json</h2>
+ <dl>
+ <dt>Type name:</dt>
+ <dd>application</dd>
+ <dt>Subtype name:</dt>
+ <dd>ld+json</dd>
+ <dt>Required parameters:</dt>
+ <dd>None</dd>
+ <dt>Optional parameters:</dt>
+ <dd>
+ <dl>
+ <dt><code>profile</code></dt>
+ <dd>
+ <p>A a non-empty list of space-separated URIs identifying specific
+ constraints or conventions that apply to a JSON-LD document according [<cite><a class="bibref" href="#bib-RFC6906">RFC6906</a></cite>].
+ A profile does not change the semantics of the resource representation
+ when processed without profile knowledge, so that clients both with
+ and without knowledge of a profiled resource can safely use the same
+ representation. The <code>profile</code> parameter <em class="rfc2119" title="MAY">MAY</em> be used by
+ clients to express their preferences in the content negotiation process.
+ If the profile parameter is given, a server <em class="rfc2119" title="SHOULD">SHOULD</em> return a document that
+ honors the profiles in the list which are recognized by the server.
+ It is <em class="rfc2119" title="RECOMMENDED">RECOMMENDED</em> that profile URIs are dereferenceable and provide
+ useful documentation at that URI. For more information and background
+ please refer to [<cite><a class="bibref" href="#bib-RFC6906">RFC6906</a></cite>].</p>
+ <p>This specification defines three values for the <code>profile</code> parameter.
+ To request or specify <a href="#expanded-document-form">expanded JSON-LD document form</a>,
+ the URI <code>http://www.w3.org/ns/json-ld#expanded</code> <em class="rfc2119" title="SHOULD">SHOULD</em> be used.
+ To request or specify <a href="#compacted-document-form">compacted JSON-LD document form</a>,
+ the URI <code>http://www.w3.org/ns/json-ld#compacted</code> <em class="rfc2119" title="SHOULD">SHOULD</em> be used.
+ To request or specify <a href="#flattened-document-form">flattened JSON-LD document form</a>,
+ the URI <code>http://www.w3.org/ns/json-ld#flattened</code> <em class="rfc2119" title="SHOULD">SHOULD</em> be used.
+ Please note that, according [<cite><a class="bibref" href="#bib-HTTP11">HTTP11</a></cite>], the value of the <code>profile</code>
+ parameter has to be enclosed in quotes (<code>"</code>) because it contains
+ special characters and, if multiple profiles are combined, whitespace.</p>
+ <p>When processing the "profile" media type parameter, it is important to
+ note that its value contains one or more URIs and not IRIs. In some cases
+ it might therefore be necessary to convert between IRIs and URIs as specified in
+ <cite><a href="http://tools.ietf.org/html/rfc3986#section-5.1">section 3 Relationship between IRIs and URIs</a></cite>
+ of [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>].</p>
+ </dd>
+ </dl>
+ </dd>
+ <dt>Encoding considerations:</dt>
+ <dd>See RFC 6839, section 3.1.</dd>
+ <dt>Security considerations:</dt>
+ <dd>See [<cite><a class="bibref" href="#bib-RFC4627">RFC4627</a></cite>]
+ <p>Since JSON-LD is intended to be a pure data exchange format for
+ directed graphs, the serialization <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> be passed through a
+ code execution mechanism such as JavaScript's <code>eval()</code>
+ function to be parsed. An (invalid) document may contain code that,
+ when executed, could lead to unexpected side effects compromising
+ the security of a system.</p>
+ <p>When processing JSON-LD documents, links to remote contexts are
+ typically followed automatically, resulting in the transfer of files
+ without the explicit request of the user for each one. If remote
+ contexts are served by third parties, it may allow them to gather
+ usage patterns or similar information leading to privacy concerns.
+ Specific implementations, such as the API defined in the
+ JSON-LD Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD-API">JSON-LD-API</a></cite>],
+ may provide fine-grained mechanisms to control this behavior.</p>
+ <p>JSON-LD contexts that are loaded from the Web over non-secure connections,
+ such as HTTP, run the risk of being altered by an attacker such that
+ they may modify the JSON-LD <a class="tref internalDFN" title="active-context" href="#dfn-active-context">active context</a> in a way that
+ could compromise security. It is advised that any application that
+ depends on a remote context for mission critical purposes vet and
+ cache the remote context before allowing the system to use it.</p>
+ <p>Given that JSON-LD allows the substitution of long IRIs with short terms,
+ JSON-LD documents may expand considerably when processed and, in the worst case,
+ the resulting data might consume all of the recipient's resources. Applications
+ should treat any data with due skepticism.</p>
+ </dd>
+ <dt>Interoperability considerations:</dt>
+ <dd>Not Applicable</dd>
+ <dt>Published specification:</dt>
+ <dd>http://www.w3.org/TR/json-ld</dd>
+ <dt>Applications that use this media type:</dt>
+ <dd>Any programming environment that requires the exchange of
+ directed graphs. Implementations of JSON-LD have been created for
+ JavaScript, Python, Ruby, PHP, and C++.
+ </dd>
+ <dt>Additional information:</dt>
+ <dd>
+ <dl>
+ <dt>Magic number(s):</dt>
+ <dd>Not Applicable</dd>
+ <dt>File extension(s):</dt>
+ <dd>.jsonld</dd>
+ <dt>Macintosh file type code(s):</dt>
+ <dd>TEXT</dd>
+ </dl>
+ </dd>
+ <dt>Person & email address to contact for further information:</dt>
+ <dd>Manu Sporny <msporny@digitalbazaar.com></dd>
+ <dt>Intended usage:</dt>
+ <dd>Common</dd>
+ <dt>Restrictions on usage:</dt>
+ <dd>None</dd>
+ <dt>Author(s):</dt>
+ <dd>Manu Sporny, Dave Longley, Gregg Kellogg, Markus Lanthaler, Niklas Lindström</dd>
+ <dt>Change controller:</dt>
+ <dd><abbr title="World Wide Web Consortium">W3C</abbr></dd>
+ </dl>
+
+ <p>Fragment identifiers used with <a href="#application-ld-json">application/ld+json</a>
+ are treated as in RDF syntaxes, as per
+ <cite><a href="http://www.w3.org/TR/rdf11-concepts/#section-fragID">RDF 1.1 Concepts and Abstract Syntax</a></cite>
+ [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</p>
+</section>
+
+<section class="appendix informative" id="acknowledgements">
+ <!--OddPage--><h2 aria-level="1" role="heading" id="h2_acknowledgements"><span class="secno">C. </span>Acknowledgements</h2><p><em>This section is non-normative.</em></p>
+
+ <p>The authors would like to extend a deep appreciation and the most sincere
+ thanks to Mark Birbeck, who contributed foundational concepts
+ to JSON-LD via his work on RDFj. JSON-LD uses a number of core concepts
+ introduced in RDFj, such as the context as a mechanism to provide an
+ environment for interpreting JSON data. Mark had also been very involved in
+ the work on RDFa as well. RDFj built upon that work. JSON-LD exists
+ because of the work and ideas he started nearly a decade ago in 2004.</p>
+
+ <p>A large amount of thanks goes out to the JSON-LD Community Group
+ participants who worked through many of the technical issues on the mailing
+ list and the weekly telecons - of special mention are François Daoust,
+ Stéphane Corlosquet, Lin Clark, and Zdenko 'Denny' Vrandečić.</p>
+
+ <p>The work of David I. Lehn and Mike Johnson are appreciated for
+ reviewing, and performing several early implementations
+ of the specification. Thanks also to Ian Davis for this work on RDF/JSON.</p>
+
+ <p>Thanks to the following individuals, in order of their first name, for
+ their input on the specification: Adrian Walker, Alexandre Passant,
+ Andy Seaborne, Ben Adida, Blaine Cook, Bradley Allen, Brian Peterson,
+ Bryan Thompson, Conal Tuohy, Dan Brickley, Danny Ayers, Daniel Leja,
+ Dave Reynolds, David Booth, David I. Lehn, David Wood, Dean Landolt,
+ Ed Summers, elf Pavlik,
+ Eric Prud'hommeaux, Erik Wilde, Fabian Christ, Jon A. Frost, Gavin Carothers,
+ Glenn McDonald, Guus Schreiber, Henri Bergius, Jose María Alvarez Rodríguez,
+ Ivan Herman, Jack Moffitt, Josh Mandel, KANZAKI Masahide, Kingsley Idehen,
+ Kuno Woudt, Larry Garfield, Mark Baker, Mark MacGillivray, Marko Rodriguez,
+ Marios Meimaris,
+ Melvin Carvalho, Nathan Rixham, Olivier Grisel, Paolo Ciccarese, Pat Hayes,
+ Patrick Logan, Paul Kuykendall, Pelle Braendgaard,
+ Peter Patel-Schneider, Peter Williams, Pierre-Antoine Champin,
+ Richard Cyganiak, Roy T. Fielding, Sandro Hawke, Simon Grant, Srecko Joksimovic,
+ Stephane Fellah, Steve Harris, Ted Thibodeau Jr., Thomas Steiner, Tim Bray,
+ Tom Morris, Tristan King, Sergio Fernández, Werner Wilms, and William Waites.</p>
+</section>
+
+
+
+<section id="references" class="appendix" typeof="bibo:Chapter" resource="#references" rel="bibo:chapter"><!--OddPage--><h2 aria-level="1" role="heading" id="h2_references"><span class="secno">D. </span>References</h2><section id="normative-references" typeof="bibo:Chapter" resource="#normative-references" rel="bibo:chapter"><h3 aria-level="2" role="heading" id="h3_normative-references"><span class="secno">D.1 </span>Normative references</h3><dl class="bibliography" about=""><dt id="bib-BCP47">[BCP47]</dt><dd rel="dcterms:requires">A. Phillips; M. Davis. <a href="http://tools.ietf.org/html/bcp47"><cite>Tags for Identifying Languages</cite></a>. September 2009. IETF Best Current Practice. URL: <a href="http://tools.ietf.org/html/bcp47">http://tools.ietf.org/html/bcp47</a>
+</dd><dt id="bib-RDF11-CONCEPTS">[RDF11-CONCEPTS]</dt><dd rel="dcterms:requires">Richard Cyganiak, David Wood, Editors. <cite><a href="http://www.w3.org/TR/2013/WD-rdf11-concepts-20130723/">RDF 1.1 Concepts and Abstract Syntax.</a></cite> 23 July 2013. W3C Last Call Working Draft (work in progress). URL: <a href="http://www.w3.org/TR/2013/WD-rdf11-concepts-20130723/">http://www.w3.org/TR/2013/WD-rdf11-concepts-20130723/</a>. The latest edition is available at <a href="http://www.w3.org/TR/rdf11-concepts/">http://www.w3.org/TR/rdf11-concepts/</a>
+</dd><dt id="bib-RFC2119">[RFC2119]</dt><dd rel="dcterms:requires">S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key words for use in RFCs to Indicate Requirement Levels.</cite></a> March 1997. Internet RFC 2119. URL: <a href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
+</dd><dt id="bib-RFC3987">[RFC3987]</dt><dd rel="dcterms:requires">M. Dürst; M. Suignard. <a href="http://www.ietf.org/rfc/rfc3987.txt"><cite>Internationalized Resource Identifiers (IRIs)</cite></a>. January 2005. RFC. URL: <a href="http://www.ietf.org/rfc/rfc3987.txt">http://www.ietf.org/rfc/rfc3987.txt</a>
+</dd><dt id="bib-RFC4627">[RFC4627]</dt><dd rel="dcterms:requires">D. Crockford. <a href="http://www.ietf.org/rfc/rfc4627.txt"><cite>The application/json Media Type for JavaScript Object Notation (JSON) (RFC 4627)</cite></a>. July 2006. RFC. URL: <a href="http://www.ietf.org/rfc/rfc4627.txt">http://www.ietf.org/rfc/rfc4627.txt</a>
+</dd><dt id="bib-RFC5988">[RFC5988]</dt><dd rel="dcterms:requires">M. Nottingham. <cite><a href="http://www.ietf.org/rfc/rfc5988.txt">Web Linking</a>.</cite> October 2010. Internet RFC 5988. URL: <a href="http://www.ietf.org/rfc/rfc5988.txt">http://www.ietf.org/rfc/rfc5988.txt</a>
+</dd></dl></section><section id="informative-references" typeof="bibo:Chapter" resource="#informative-references" rel="bibo:chapter"><h3 aria-level="2" role="heading" id="h3_informative-references"><span class="secno">D.2 </span>Informative references</h3><dl class="bibliography" about=""><dt id="bib-HTTP11">[HTTP11]</dt><dd rel="dcterms:references">R. Fielding et al. <a href="http://www.ietf.org/rfc/rfc2616.txt"><cite>Hypertext Transfer Protocol - HTTP/1.1</cite></a>. June 1999. RFC. URL: <a href="http://www.ietf.org/rfc/rfc2616.txt">http://www.ietf.org/rfc/rfc2616.txt</a>
+</dd><dt id="bib-JSON-LD-API">[JSON-LD-API]</dt><dd rel="dcterms:references">Markus Lanthaler, Gregg Kellogg, Manu Sporny, Editors. <cite><a href="http://www.w3.org/TR/2013/CR-json-ld-api-20130910/">JSON-LD 1.0 Processing Algorithms and API</a>.</cite> W3C Candidate Recommendation (work in progress). URL: <a href="http://www.w3.org/TR/2013/CR-json-ld-api-20130910/">http://www.w3.org/TR/2013/CR-json-ld-api-20130910/</a>. The latest edition is available at <a href="http://www.w3.org/TR/json-ld-api/">http://www.w3.org/TR/json-ld-api/</a>
+</dd><dt id="bib-JSON-LD-TESTS">[JSON-LD-TESTS]</dt><dd rel="dcterms:references"><cite><a href="http://www.w3.org/2013/json-ld-tests/">JSON-LD 1.0 Test Suite</a></cite>. W3C Test Suite (work in progress). URL: <a href="http://www.w3.org/2013/json-ld-tests/">http://www.w3.org/2013/json-ld-tests/</a>
+</dd><dt id="bib-LINKED-DATA">[LINKED-DATA]</dt><dd rel="dcterms:references">Tim Berners-Lee. <cite><a href="http://www.w3.org/DesignIssues/LinkedData.html">Linked Data</a></cite>. Personal View, imperfect but published. URL: <a href="http://www.w3.org/DesignIssues/LinkedData.html">http://www.w3.org/DesignIssues/LinkedData.html</a>
+</dd><dt id="bib-MICRODATA">[MICRODATA]</dt><dd rel="dcterms:references">Ian Hickson, Editor. <cite><a href="http://www.w3.org/TR/2012/WD-microdata-20121025/">HTML Microdata</a>.</cite> 25 October 2012. W3C Working Draft (work in progress). URL: <a href="http://www.w3.org/TR/2012/WD-microdata-20121025/">http://www.w3.org/TR/2012/WD-microdata-20121025/</a>. The latest edition is available at <a href="http://www.w3.org/TR/microdata/">http://www.w3.org/TR/microdata/</a>
+</dd><dt id="bib-MICROFORMATS">[MICROFORMATS]</dt><dd rel="dcterms:references"><a href="http://microformats.org"><cite>Microformats</cite></a>. URL: <a href="http://microformats.org">http://microformats.org</a>
+</dd><dt id="bib-RDF-SCHEMA">[RDF-SCHEMA]</dt><dd rel="dcterms:references">Dan Brickley; Ramanathan Guha. <a href="http://www.w3.org/TR/rdf-schema"><cite>RDF Vocabulary Description Language 1.0: RDF Schema</cite></a>. 10 February 2004. W3C Recommendation. URL: <a href="http://www.w3.org/TR/rdf-schema">http://www.w3.org/TR/rdf-schema</a>
+</dd><dt id="bib-RDF11-MT">[RDF11-MT]</dt><dd rel="dcterms:references">Patrick J. Hayes, Peter F. Patel-Schneider, Editors. <cite><a href="http://www.w3.org/TR/2013/WD-rdf11-mt-20130723/">RDF 1.1 Semantics.</a></cite> 23 July 2013. W3C Last Call Working Draft (work in progress). URL: <a href="http://www.w3.org/TR/2013/WD-rdf11-mt-20130723/">http://www.w3.org/TR/2013/WD-rdf11-mt-20130723/</a>. The latest edition is available at <a href="http://www.w3.org/TR/rdf11-mt/">http://www.w3.org/TR/rdf11-mt/</a>
+</dd><dt id="bib-RDFA-CORE">[RDFA-CORE]</dt><dd rel="dcterms:references">Ben Adida; Mark Birbeck; Shane McCarron; Ivan Herman et al. <a href="http://www.w3.org/TR/rdfa-core/"><cite>RDFa Core 1.1 - Second Edition</cite></a>. 22 August 2013. W3C Recommendation. URL: <a href="http://www.w3.org/TR/rdfa-core/">http://www.w3.org/TR/rdfa-core/</a>
+</dd><dt id="bib-RFC3986">[RFC3986]</dt><dd rel="dcterms:references">T. Berners-Lee; R. Fielding; L. Masinter. <a href="http://www.ietf.org/rfc/rfc3986.txt"><cite>Uniform Resource Identifier (URI): Generic Syntax (RFC 3986)</cite></a>. January 2005. RFC. URL: <a href="http://www.ietf.org/rfc/rfc3986.txt">http://www.ietf.org/rfc/rfc3986.txt</a>
+</dd><dt id="bib-RFC6839">[RFC6839]</dt><dd rel="dcterms:references">Tony Hansen, Alexey Melnikov. <cite><a href="http://www.ietf.org/rfc/rfc6839.txt">Additional Media Type Structured Syntax Suffixes</a>.</cite> January 2013. Internet RFC 6839. URL: <a href="http://www.ietf.org/rfc/rfc6839.txt">http://www.ietf.org/rfc/rfc6839.txt</a>
+</dd><dt id="bib-RFC6906">[RFC6906]</dt><dd rel="dcterms:references">Erik Wilde. <cite><a href="http://www.ietf.org/rfc/rfc6906.txt">The 'profile' Link Relation Type</a>.</cite> March 2013. Internet RFC 6906. URL: <a href="http://www.ietf.org/rfc/rfc6906.txt">http://www.ietf.org/rfc/rfc6906.txt</a>
+</dd><dt id="bib-TURTLE">[TURTLE]</dt><dd rel="dcterms:references">Eric Prud'hommeaux, Gavin Carothers, Editors. <cite><a href="http://www.w3.org/TR/2013/CR-turtle-20130219/">Turtle: Terse RDF Triple Language.</a></cite> 19 February 2013. W3C Candidate Recommendation (work in progress). URL: <a href="http://www.w3.org/TR/2013/CR-turtle-20130219/">http://www.w3.org/TR/2013/CR-turtle-20130219/</a>. The latest edition is available at <a href="http://www.w3.org/TR/turtle/">http://www.w3.org/TR/turtle/</a>
+</dd></dl></section></section></body></html>