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+<head>
+ <title>Data Catalog Vocabulary (DCAT)</title>
+ <style type="text/css">
+ table {
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+ content: "Editor's Note";
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+<body>
+<p><a href="http://www.w3.org/"><img width="72" height="48" src="http://www.w3.org/Icons/w3c_home" alt="W3C"></a></p>
+<h1 class="title" id="title">Data Catalog Vocabulary (DCAT)</h1>
+<h2 id="w3c-working-draft-06-january-2012">W3C Working Draft 06 January 2012</h2>
+<dl>
+ <dt>This version:</dt>
+ <dd><a href="http://www.w3.org/TR/2011/WD-DCAT-@@@@@@@/">http://www.w3.org/TR/2011/WD-DCAT-@@@@@@@</a></dd>
+ <dt>Latest published version:</dt>
+ <dd><a href="http://www.w3.org/TR/DCAT/">http://www.w3.org/TR/DCAT/</a></dd>
+ <dt>Previous published version:</dt>
+ <dd>None</dd>
+ <dt>Editors:</dt>
+ <dd><a href="mailto:fadi.maali@deri.org">Fadi Maali</a>, <a href="http://www.deri.org/">DERI</a></dd>
+ <dd><a href="mailto:olyerickson@gmail.com">John Erickson</a>, <a href="http://tw.rpi.edu">Tetherless World Constellation (RPI)</a></dd>
+ <dd><a href="mailto:phila@w3.org">Phil Archer</a>, <a href="/">W3C/ERCIM</a></dd>
+</dl>
+<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2010-2011
+ <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>™</sup>
+ (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>,
+ <a href="http://www.ercim.eu/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
+ <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
+ <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 id="abstract" class="introductory section">
+ <h2>Abstract</h2>
+ <p>@@@ To Do @@@</p>
+</div>
+<div id="sotd" class="introductory section">
+ <h2>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
+ W3C publications and the latest revision of this technical report can be
+ found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
+ at http://www.w3.org/TR/.</em></p>
+ <p>This is the First Public Working Draft of DCAT in W3C's TR space and
+ signals its move to the Recommendations Track. DCAT was first
+ developed and published by DERI and enjoys widespread use at the time of
+ this publication. The <a href="http://vocab.deri.ie/dcat">original vocabulary</a>
+ was further developed on the @@@eGov Interest Group's wiki@@@ before being brought onto the
+ Recommendation Track by the
+ <a href="http://www.w3.org/2011/gld/">Governmenet Linked Data Working Group</a>
+ which intends for it to become a Recommendation.
+ If you wish to make comments regarding this document,
+ please send them to <a href="mailto:public-gld-wg@w3.org">public-gld-wg@w3.org</a>
+ (<a href="mailto:public-gld-wg-request@w3.org?subject=subscribe">subscribe</a>,
+ <a href="http://lists.w3.org/Archives/Public/public-gld-wg/">archives</a>).
+ All feedback is welcome.</p>
+ <p>Publication as a Working Draft does not imply endorsement by the W3C
+ 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 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
+ 2004 W3C Patent Policy</a>. W3C maintains a
+ <a href="http://www.w3.org/2004/01/pp-impl/49309/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 W3C Patent Policy</a>.</p>
+</div>
+
+<h2 id="toc"">Table of Contents</h2>
+ <ul class="toc">
+ <li><a href="#intro">Introduction</a></li>
+ <li><a href="#conformance">Conformance</a></li>
+ <li><a href="#terminology">Terminology</a></li>
+ <li><a href="#ns">Namespaces</a></li>
+ <li><a href="#overview">Vocabulary Overview</a></li>
+ <li><a href="#example">Example</a></li>
+ <li><a href="#encoding">Encoding of Property Values</a></li>
+
+ <li><a href="#Class:_Catalog">Class: Catalog</a>
+ <ul>
+ <li><a href="#Property:_homepage">Property: homepage</a></li>
+ <li><a href="#Property:_publisher">Property: publisher</a></li>
+ <li><a href="#Property:_spatial.2Fgeographic_coverage">Property: spatial/geographic coverage</a></li>
+ <li><a href="#Property:_themes">Property: themes</a></li>
+ <li><a href="#Property:_title">Property: title</a></li>
+ <li><a href="#Property:_description">Property: description</a></li>
+ <li><a href="#Property:_language">Property: language</a></li>
+ <li><a href="#Property:_license">Property: license</a></li>
+ <li><a href="#Property:_dataset">Property: dataset</a></li>
+ <li><a href="#Property:_catalog_record">Property: catalog record</a></li>
+ </ul></li>
+
+ <li><a href="#Class:_Catalog_record">Class: Catalog record</span></a>
+ <ul>
+ <li><a href="#Property:_listing_date">Property: listing date</a></li>
+ <li><a href="#Property:_update.2Fmodification_date">Property: update/modification date</a></li>
+ <li><a href="#Property:_dataset_2">Property: dataset</a></li>
+ </ul></li>
+
+ <li><a href="#Class:_Dataset">Class: Dataset</a>
+ <ul>
+ <li><a href="#Property:_update.2Fmodification_date_2">Property: update/modification date</a></li>
+ <li><a href="#Property:_title_2">Property: title</a></li>
+ <li><a href="#Property:_description_2">Property: description</a></li>
+ <li><a href="#Property:_publisher_2">Property: publisher</a></li>
+ <li><a href="#Property:_release_date">Property: release date</a></li>
+ <li><a href="#Property:_frequency">Property: frequency</a></li>
+ <li><a href="#Property:_identifier">Property: identifier</a></li>
+ <li><a href="#Property:_spatial.2Fgeographical_coverage">Property: spatial/geographical coverage</a></li>
+ <li><a href="#Property:_temporal_coverage">Property: temporal coverage</a></li>
+ <li><a href="#Property:_language_2">Property: language</a></li>
+ <li><a href="#Property:_license_2">Property: license</a></li>
+ <li><a href="#Property:_granularity">Property: granularity</a></li>
+ <li><a href="#Property:_data_dictionary">Property: data dictionary</a></li>
+ <li><a href="#Property:_data_quality">Property: data quality</a></li>
+ <li><a href="#Property:_theme.2Fcategory">Property: theme/category</a></li>
+ <li><a href="#Property:_keyword.2Ftag">Property: keyword/tag</a></li>
+ <li><a href="#Property:_related_documents">Property: related documents</a></li>
+ <li><a href="#Property:_dataset_distribution">Property: dataset distribution</a></li>
+ </ul></li>
+ <li><a href="#Class:_Distribution">Class: Distribution</a>
+ <ul>
+ <li><a href="#Property:_access.2Fdownload">Property: access/download</a></li>
+ <li><a href="#Property:_size">Property: size</a></li>
+ <li><a href="#Property:_format">Property: format</a></li>
+ </ul></li>
+
+ <li><a href="#Class:_Download">Class: Download</a></li>
+ <li><a href="#Class:_WebService"><span class="toctext">Class: WebService</a></li>
+ <li><a href="#Class:_Feed">Class: Feed</a></li>
+ <li><a href="#Class:_Category_and_category_scheme">Class: Category and category scheme</a></li>
+ <li><a href="#Class:_Organization.2FPerson">Class: Organization/Person</a></li>
+ <li><a href="#Extending_the_vocabulary">Extending the vocabulary</a></li>
+ </ul>
+
+<h2 id="intro">Introduction</h2>
+<p>This document does not prescribe any particular method of deploying data
+expressed in DCAT. There are many options, such as SPARQL endpoints, RDFa,
+RDF/XML, Turtle. Examples here use Turtle, but that's just because of Turtle's
+readability.</p>
+
+<h2 id="conformance">Conformance</h2>
+
+<h2 id="terminology">Terminology</h2>
+
+<h2 id="ns">Namespaces</h2>
+<p>The namespace for DCAT is <code>http://www.w3.org/ns/dcat#</code>. However,
+it should be noted that DCAT makes extensive use of terms from other vocabularies,
+in particular Dublin Core. DCAT itself defines a minimal set of classes and
+properties of its own. A full set of namespaces and prefixes used in this
+document is shown in the table below.</p>
+
+<table id="namespaces">
+ <thead><tr><th>Prefix</th><th>Namespace</th></tr></thead>
+ <tbody>
+ <tr><td>dcat</td><td>http://www.w3.org/ns/dcat#</td></tr>
+ <tr><td>dcterms</td><td>http://purl.org/can never remember</td></tr>
+ <tr><td>foaf </td><td>http://xmlns.com/foaf/0.1/</td></tr>
+ </tbody>
+</table>
+
+<h2 id="overview">Vocabulary Overview</h2>
+<p>DCAT is an RDF vocabulary to represent government data catalogs such as data.gov and data.gov.uk. DCAT defines three main classes:</p>
+<ul><li> dcat:Catalog represents the catalog
+</li><li> dcat:Dataset represents a dataset in a catalog
+</li><li> dcat:Distribution represents an accessible form of a dataset as for example a downloadable file, an RSS feed or a web service that provides the data.
+</li></ul>
+<p>Another important class in DCAT is dcat:CatalogRecord which describes a dataset entry in the catalog. Notice that while dcat:Dataset represents the dataset itself, dcat:CatalogRecord represents the record that describes a dataset in the catalog. The use of the CatalogRecord is considered optional. It is used to capture provenance information about dataset entries in a catalog. If this distinction is not necessary then CatalogRecord can be safely ignored.</p>
+<p>@@Fadi: I will update the figure once the list of properties are listed</p>
+<p><img alt="UML model of DCAT classes and properties" src="dcat-model.jpg"/></p>
+
+<h2 id="Example">Example</h2>
+<p>This example provides a quick overview of how dcat might be used to represent a government catalog and its datasets.
+</p><p>First, the catalog description:
+</p>
+<pre> :catalog
+ a dcat:Catalog ;
+ dct:title "Imaginary catalog" ;
+ rdfs:label "Imaginary catalog" ;
+ foaf:homepage <<a href="http://example.org/catalog" class="external free" title="http://example.org/catalog" rel="nofollow">http://example.org/catalog</a>> ;
+ dct:publisher :transparency-office ;
+ dcat:themes :themes ;
+ dct:language "en"^^xsd:language ;
+ dcat:dataset :dataset/001 ;
+ .
+</pre>
+<p>The publisher of the catalog has the relative URI :transparency-office. Further description of the publisher can be provided as in the following example:
+</p>
+<pre> :transparency-office
+ a foaf:Agent ;
+ rdfs:label "Transparency Office" ;
+ .
+</pre>
+<p>The catalog classify its datasets according to a set of domains represented by the relative URI :themes. SKOS can be used to describe the domains used:
+</p>
+<pre> :themes
+ a skos:ConceptScheme ;
+ skos:prefLabel "A set of domains to classify documents" ;
+ .
+</pre>
+<p>The catalog connect to each of its datasets via dcat:dataset. In the example above, an example dataset was mentioned with the relative URI :dataset/001. A possible description of it using dcat is shown below:
+</p>
+<pre> :dataset/001
+ a dcat:Dataset ;
+ dct:title "Imaginary dataset" ;
+ dcat:keyword "accountability","transparency" ,"payments" ;
+ dcat:theme :themes/accountability ;
+ dct:issued "2011-12-05"^^xsd:date ;
+ dct:updated "2011-12-05"^^xsd:date ;
+ dct:publisher :agency/finance-ministry ;
+ dct:accrualPeriodicity "every six months" ;
+ dct:language "en"^^xsd:language ;
+ dcat:Distribution :dataset/001/csv ;
+ .
+</pre>
+<p>Notice that this dataset is classified under the domain represented by the relative URI :themes/accountability. This should be part of the domains set identified by the URI :themes that was used to describe the catalog domains. An example SKOS description
+</p>
+<pre> :themes/accountability
+ a skos:Concept ;
+ skos:inScheme :themes ;
+ skos:prefLabel "Accountability" ;
+ .
+</pre>
+<p>The dataset can be downloaded in CSV format via the distribution represented by :dataset/001/csv.
+</p>
+<pre> :dataset/001/csv
+ a dcat:Distribution ;
+ dcat:accessURL <<a href="http://www.example.org/files/001.csv" class="external free" title="http://www.example.org/files/001.csv" rel="nofollow">http://www.example.org/files/001.csv</a>> ;
+ dct:title "CSV distribution of imaginary dataset 001" ;
+ dct:format [
+ a dct:IMT;
+ rdf:value "text/csv";
+ rdfs:label "CSV"
+ ]
+ .
+</pre>
+<p>Finally, if the catalog publisher decides to keep metadata describing its records (i.e. the records containing metadata describing the datasets) dcat:CatalogRecord can be used. For example, :dataset/001 was issued on 2011-12-05. however, its description on Imaginary Catalog was added on 2011-12-11. This can be represented by dcat:
+</p>
+<pre> :record/001
+ a dcat:CatalogRecord ;
+ foaf:primaryTopic :dataset/001 ;
+ dct:issued "2011-12-11"^^xsd:date ;
+ .
+ :catalog
+ dcat:record :record/001 ;
+ .
+</pre>
+<a name="Encoding_of_property_values" id="Encoding_of_property_values"></a><h2> <span class="mw-headline"> Encoding of property values </span></h2>
+<ul><li> Values like "unknown" or "unspecified" should never be used, and if present in the original database should be filtered for publishing. Instead, the property should simply be omitted.
+</li><li> @@@ policy for using resources vs. literals
+</li></ul>
+<h2 id="Class:_Catalog">Class: Catalog</h2>
+<p>A data catalog is a curated collection of metadata about datasets.</p>
+<table class="definition">
+ <thead><tr><th>RDF class:</th><th><a href="http://www.w3.org/ns/dcat#Catalog">dcat:Catalog</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Usage note:</td><td>Typically, a web-based data catalog is represented as a single instance of this class.</td></tr>
+ <tr><td class="prop">See also:</td><td> <a href="#Class:_Catalog_record">Catalog record</a>, <a href="#Class:_Dataset">Dataset</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_homepage">Property: homepage</h3>
+<p>The homepage of the catalog.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://xmlns.com/foaf/0.1/homepage">foaf:homepage</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://xmlns.com/foaf/0.1/Document">foaf:Document</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td><a href="http://xmlns.com/foaf/0.1/homepage">foaf:homepage</a> is an inverse functional property (IFP) which means that it should be unique and precisely identify the catalog. This allows smushing various descriptions of the catalog when different URIs are used.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_publisher">Property: publisher</h3>
+<p>The entity responsible for making the catalogue online.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/publisher">dcterms:publisher</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://xmlns.com/foaf/0.1/Agent">foaf:Agent</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_spatial.2Fgeographic_coverage">Property: spatial/geographic coverage></h3>
+<p>The geographical area covered by the catalogue.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/spatial">dcterms:spatial</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/terms/Location">dcterms:Location</a> (Spatial region or named place)</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_themes">Property: themes</h3>
+<p>The knowledge organization system (KOS) used to classify catalog's datasets.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#themeTaxonomy">dcat:themeTaxonomy</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2004/02/skos/core#ConceptScheme">skos:ConceptScheme</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_title">Property: title</h3>
+<p>A name given to the catalog.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/title">dcterms:title</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_description">Property: description</h3>
+<p>free-text account of the catalog.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/description">dcterms:description</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_language">Property: language</h3>
+<p>The language of the catalog. This refers to the language used in the textual metadata describing titles, descriptions, etc. of the datasets in the catalog.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/language">dct:language</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a> a string representing the code of the language as described in <a href="http://www.ietf.org/rfc/rfc3066.txt">http://www.ietf.org/rfc/rfc3066.txt</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>Multiple values can be used. The publisher might also choose to describe the language on the dataset level (see <a href="#dataset_language">dataset language</a>).</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_license">Property: license</h3>
+<p>This describes the license under which the <strong>catalog</strong> can be used/reused and <strong>not the datasets</strong>. Even if the license of the catalog applies to all of its datasets it should be replicated on each dataset.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/license">dcterms:license</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/dcmitype/LicenseDocument">dctype:LicenseDocument</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>To allow automatic analysis of datasets, it is important to use canonical identifiers for well-known licenses, see @@@void guide@@@ for a list.</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#dataset_license" title="">dataset license</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_dataset">Property: dataset</h3>
+<p>A dataset that is part of the catalog.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#dataset">dcat:dataset</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_catalog_record">Property: catalog record</h3>
+<p>A catalog record that is part of the catalog.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#record">dcat:record</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/ns/dcat#CatalogRecord"dcat:CatalogRecord</a></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_Catalog_record">Class: Catalog record</h2>
+<p>A record in a data catalog, describing a single dataset.</p>
+<table class="definition">
+ <thead><tr><th>RDF Class:</th><th><a href="http://www.w3.org/ns/dcat#CatalogRecord">dcat:CatalogRecord</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Usage note</td><td>This class is optional and not all catalogs will use it. It exists for catalogs where a distinction is made between metadata about a <em>dataset</em> and metadata about the <em>dataset's entry in the catalog</em>. For example, the <i>publication date</i> property of the <i>dataset</i> reflects the date when the information was originally made available by the publishing agency, while the publication date of the <i>catalog record</i> is the date when the dataset was added to the catalog. In cases where both dates differ, or where only the latter is known, the <em>publication date</em> should only be specified for the catalog record.</td></tr>
+ <tr><td class="prop">See also</td><td><a href="#Class:_Dataset">Dataset</a></td></tr>
+ </tbody>
+</table>
+
+<p>In web-based catalogs, the URL of the catalog page should be used as URI for the catalog record <em>if it is a permalink</em>.</p>
+<p>If named graphs are used, all RDF triples describing the catalog record, the dataset, and its distributions, should go into a graph named with the catalog record's URI.</p>
+
+<h3 id="Property:_listing_date">Property: listing date</h3>
+<p>The date of listing the corresponding dataset in the catalog.</p>
+
+<p class="editorsnote">See <a href="https://www.w3.org/2011/gld/track/issues/3">Issue-3</a></p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/issued">dcterms:issued</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a> typed as <a href="http://www.w3.org/TR/xmlschema-2/#date">xsd:date</a>. The date is encoded as a literal in "YYYY-MM-DD" form (<a href="http://www.w3.org/TR/NOTE-datetime">ISO 8601 Date and Time Formats</a>). If the specific day or month are not known, then 01 should be specified.</td></tr>
+ <tr><td class="prop">Usage note:</td><td>This indicates the date of listing the dataset in the catalog and not the publication date of the dataset itself.</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Property:_release_date" title=""> dataset release date</a></td></tr>
+ </tbody>
+</table>
+
+
+<h3 id="Property:_update.2Fmodification_date">Property: update/modification date</h3>
+<p>Most recent date on which the catalog entry was changed, updated or modified.</p>
+<p class="editorsnote">See <a href="https://www.w3.org/2011/gld/track/issues/3">Issue-3</a></p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/modified">dcterms:modified</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a> typed as <a href="http://www.w3.org/TR/xmlschema-2/#date">xsd:date</a>. The date is encoded as a literal in "YYYY-MM-DD" form (<a href="http://www.w3.org/TR/NOTE-datetime">ISO 8601 Date and Time Formats</a>). If the specific day or month are not known, then 01 should be specified.</td></tr>
+ <tr><td class="prop">Usage note:</td><td>This indicates the date of last change of a catalog entry, i.e. the catalog metadata description of the dataset, and not the date of the dataset itself.</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#dataset_modification_date" title=""> dataset modification date</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_dataset_2">Property: dataset</h3>
+<p>Links the catalog record to the dcat:Dataset resource described in the record.</p>
+
+<p class="editorsnote">See <a href="https://www.w3.org/2011/gld/track/issues/4">Issue-4</a></p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://xmlns.com/foaf/0.1/primaryTopic">foaf:primaryTopic</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_Dataset">Class: Dataset</h2>
+<p>A collection of data, published or curated by a single source, and available for access or download in one or more formats.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Class:</th><th><a href="http://www.w3.org/ns/dcat#Dataset">dcat:Dataset</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Usage note:</td><td>This class represents the actual dataset as published by the dataset publisher. In cases where a distinction between the actual dataset and its entry in the catalog is necessary (because metadata such as modification date and maintainer might differ), the <i><a href="#Class:_Catalog_record">catalog record</a></i> class can be used for the latter.</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Class:_Catalog_record" title="">Catalog record</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_update.2Fmodification_date_2">Property: update/modification date</h3>
+<p>Most recent date on which the dataset was changed, updated or modified.</p>
+<p class="editorsnote">See <a href="https://www.w3.org/2011/gld/track/issues/3">Issue-3</a></p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/modified">dcterms:modified</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a> typed as <a href="http://www.w3.org/TR/xmlschema-2/#date">xsd:date</a>. The date is encoded as a literal in "YYYY-MM-DD" form (<a href="http://www.w3.org/TR/NOTE-datetime">ISO 8601 Date and Time Formats</a>). If the specific day or month are not known, then 01 should be specified.</td></tr>
+ <tr><td class="prop">Usage note:</td><td>The value of this property indicates a change to the actual dataset, not a change to the catalog record. An absent value may indicate that the dataset has never changed after its initial publication, or that the date of last modification is not known, or that the dataset is continuously updated. <b>Example:</b> 2010-05-07</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Property:_frequency">frequency</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_title_2">Property: title</h3>
+<p>A name given to the dataset.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/title">dcterms:title</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_description_2">Property: description</h3>
+<p>free-text account of the dataset.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/description">dcterms:description</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_publisher_2">Property: publisher</h3>
+<p>An entity responsible for making the dataset available.</p>
+<p class="editorsnote">See <a href="https://www.w3.org/2011/gld/track/issues/4">Issue-4</a></p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/publisher">dcterms:publisher</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://xmlns.com/foaf/0.1/Organization">foaf:Organization</a></td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Class:_Organization.2FPerson" title="">Class: Organization/Person</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_release_date">Property: release date</h3>
+<p>Date of formal issuance (e.g., publication) of the dataset.</p>
+<p class="editorsnote">See <a href="https://www.w3.org/2011/gld/track/issues/3">Issue-3</a></p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/issued">dcterms:issued</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a> typed as <a href="http://www.w3.org/TR/xmlschema-2/#date">xsd:date</a>. The date is encoded as a literal in "YYYY-MM-DD" form (<a href="http://www.w3.org/TR/NOTE-datetime">ISO 8601 Date and Time Formats</a>). If the specific day or month are not known, then 01 should be specified.</td></tr>
+ <tr><td class="prop">Usage note:</td><td>This property should be set using the first known date of issuance. <b>Example:</b> 2010-05-07</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_frequency">Property: frequency</h3>
+<p>The frequency with which dataset is published.</p>
+<p class="editorsnote">See <a href="https://www.w3.org/2011/gld/track/issues/5">Issue-5</a></p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/accrualPeriodicity">dcterms:accrualPeriodicity</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/terms/Frequency">dcterms:Frequency</a> (A rate at which something recurs)</td></tr>
+ <tr><td class="prop">Usage note:</td><td>@@@ values should come from a controlled vocabulary i.e. predefined set of resources. It could use values like <a href="http://www.placetime.com/interval/gregorian/">placetime.com intervals</a></td></tr>
+ <tr><td class="prop">Domain:</td><td><a href="http://purl.org/dc/terms/Collection">dcterms:Collection</a> so, a Catalog must be a dcterms:Collection as well.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_identifier">Property: identifier</h3>
+<p>A unique identifier of the dataset.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/identifier">dcterms:identifier</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>The identifier might be used to coin permanent and unique URI for the dataset, but still having it represented explicitly is useful.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_spatial.2Fgeographical_coverage">Property: spatial/geographical coverage</h3>
+<p>Spatial coverage of the dataset.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/spatial">dcterms:spatial</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/terms/Location">dcterms:Location</a> (A spatial region or named place)</td></tr>
+ <tr><td class="prop">Usage note:</td><td> @@@ controlled vocabulary. geonames???</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_temporal_coverage">Property: temporal coverage</h3>
+<p>@@@ The temporal period that the dataset covers.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/temporal">dcterms:temporal</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/terms/PeriodOfTime">dcterms:PeriodOfTime</a> (An interval of time that is named or defined by its start and end dates)</td></tr>
+ <tr><td class="prop">Usage note:</td><td> @@@ controlled vocabulary. <a href="http://www.placetime.com/">http://www.placetime.com/</a> might be an option???</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_language_2">Property: language</h3>
+<p>The language of the dataset.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/language">dct:language</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a> a string representing the code of the language as described in <a href="http://www.ietf.org/rfc/rfc3066.txt">http://www.ietf.org/rfc/rfc3066.txt</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>This overrides the value of the <a href="#Property:_language">catalog language</a> in case of conflict.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_license_2">Property: license</h3>
+<p>The license under which the dataset is published and can be reused.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/license">dcterms:license</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/dcmitype/LicenseDocument">dctype:LicenseDocument</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>See <a href="http://www.w3.org/TR/void/#license">Section 2.4 of Describing Linked Datasets with the VoID Vocabulary</a>.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_granularity">Property: granularity</h3>
+<p>describes the level of granularity of data. @@@ elaborate more@@@</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#">dcat:granularity</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Resource">rdfs:Resource</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>This is usually geographical or temporal but can also be other dimension e.g. Person can be used to describe granularity of a dataset about average income.</td></tr>
+ </tbody>
+</table>
+<p>A set of sample values used in data.gov: country, county, longitude/latitude, region, plane, airport.</p>
+
+<h3 id="Property:_data_dictionary">Property: data dictionary</h3>
+<p>provides some sort of description that helps understanding the data. This usually consisits of a table providing explanation of columns meaning, values interpretation and acronyms/codes used in the data.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#dataDictionary">dcat:dataDictionary</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://xmlns.com/foaf/0.1/Document">foaf:Document</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>@@@ Review @@@ It is rarely provided in the current catalogs and does not have a consistent usage, however when it is provided it is a link to some document or embeded in a document packaged together with the dataset. It is recommended to represent it as a resource having the URL of the online document as its URI. Statistical datasets, as a particular yet common case, can have a more structured description and the on-progress work on <a href="http://groups.google.com/group/publishing-statistical-data">SDMX+RDF</a> can be utilized here.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_data_quality">Property: data quality</h3>
+<p>describes the quality of data.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#dataQuality">dcat:dataQuality</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>@@@Review@@@ This is a very general property and it is not clear how exactly it will be used as catalogs currently do not use it or use it with meaningless values. Catalogs are expected to define more specific sub-properties to describe quality characteristics e.g. statistical data usually have a lot to describe about the quality of sampling, collection mode, non-response adjustment…</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_theme.2Fcategory">Property: theme/category</h3>
+<p>The main category of the dataset. A dataset can have multiple themes.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#theme">dcat:theme</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2004/02/skos/core#Concept">skos:Concept</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>The set of <a href="http://www.w3.org/2004/02/skos/core#Concept">skos:Concept</a>s used to categorize the datasets are organized in a <a href="http://www.w3.org/2004/02/skos/core#ConceptScheme">skos:ConceptScheme</a> describing all the categories and their relations in the catalog.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_keyword.2Ftag"></a>Property: keyword/tag</h3>
+<p>A keyword or tag describing the dataset.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#keyword">dcat:keyword</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_related_documents">Property: related documents</h3>
+<p>A related document such as technical documentation, agency program page, citation, etc.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/references">dcterms:references</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td>Has no defined range</td></tr>
+ <tr><td class="prop">Usage note:</td><td>The value is the URI of the related document.</td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_dataset_distribution">Property: dataset distribution</h3>
+<p>Connects a dataset to its available distributions.</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#distribution">dcat:distribution</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/ns/dcat#">dcat:Distribution</a></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_Distribution">Class: Distribution</h2>
+<p>Represents a specific available form of a dataset. Each dataset might be available in different forms, these forms might represent different formats of the dataset, different endpoints,... Examples of Distribution include a downloadable CSV file, an XLS file representing the dataset, an RSS feed…</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#Distribution">dcat:Distribution</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td>Has no defined range</td></tr>
+ <tr><td class="prop">Usage note:</td><td>This represents a general availability of a dataset it implies no information about the actual access method of the data, i.e. whether it is a direct download, API, or a splash page. Use one of its subclasses when the particular access method is known.</td></tr>
+ <tr><td class="prop">See also</td><td><a href="#Class:_Download">Download</a>, <a href="#Class:_WebService">WebService</a>, <a href="#Class:_Feed">Feed</a></td></tr>
+ </tbody>
+</table>
+
+
+<h3 id="Property:_access.2Fdownload">Property: access/download</h3>
+<p>points to the location of a distribution. This can be a direct download link, a link to an HTML page containing a link to the actual data, Feed, Web Service etc. the semantic is determined by its domain (Distribution, Feed, WebService, Download).</p>
+<p class="editorsnote">If the value is always a URI, shouldn't the range be rdfs:Resource?</p>
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#accessURL">dcat:accessURL</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Literal">rdfs:Literal</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>the value is a URL.</td></tr>
+ <tr><td class="prop">See also</td><td><a href="#Class:_Download">Download</a>, <a href="#Class:_WebService">WebService</a>, <a href="#Class:_Feed">Feed</a></td></tr>
+ </tbody>
+</table>
+
+
+<h3 id="Property:_size">Property: size</h3>
+<p>The size of a distribution.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://www.w3.org/ns/dcat#size">dcat:size</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://www.w3.org/2000/01/rdf-schema#Resource">rdfs:Resource</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td><a href="http://www.w3.org/ns/dcat#size">dcat:size</a> is usually used with a blank node described using <a href="http://www.w3.org/2000/01/rdf-schema#label">rdfs:label</a> and <a href="http://www.w3.org/ns/dcat#bytes">dcat:bytes</a>.</td></tr>
+ <tr><td class="prop">Example:</td><td><pre> :distribution dcat:size [dcat:bytes 5120^^xsd:integer; rdfs:label "5KB"]</pre></td></tr>
+ </tbody>
+</table>
+
+<h3 id="Property:_format">Property: format</h3>
+<p>the file format of the distribution.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Property:</th><th><a href="http://purl.org/dc/terms/format">dcterms:format</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/terms/MediaTypeOrExtent">dcterms:MediaTypeOrExtent</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>MIME type is used for values. A list of MIME types URLs can be found at <a href="http://www.iana.org/assignments/media-types/">IANA</a>. However ESRI Shape files have no specific MIME type (A Shape distribution is actually a collection of files), currently this is still an open question? @@@.</td></tr>
+ <tr><td class="prop">Example:</td><td>
+<pre>:distribution dcterms:format [
+ a dcterms:IMT;
+ rdf:value "text/csv";
+ rdfs:label "CSV"
+]</pre></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_Download">Class: Download</h2>
+<p>Represents a downloadable distribution of a dataset.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Class:</th><th><a href="http://www.w3.org/ns/dcat#Download">dcat:Download</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="#Property:_access.2Fdownload"> accessUrl</a> of the Download distribution should be a <strong>direct download link</strong> (a one-click access to the data file).</a></td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Class:_Distribution">Distribution</a>, <a href="#Class:_WebService">WebService</a>, <a href="#Class:_Feed">Feed</a></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_WebService">Class: WebService</h2>
+<p>Represents a web service that enables access to the data of a dataset.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Class:</th><th><a href="http://www.w3.org/ns/dcat#WebService">dcat:WebService</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Range:</td><td><a href="http://purl.org/dc/terms/MediaTypeOrExtent">dcterms:MediaTypeOrExtent</a></td></tr>
+ <tr><td class="prop">Usage note:</td><td>Describe the web service using <a href="#Property:_access.2Fdownload"> accessUrl</a>, <a href="#Property:_format"> format</a> and <a href="#Property:_size"> size</a>. Further description of the web service is out the scope of dcat.</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Class:_Distribution">Distribution</a>, <a href="#Class:_Download">Download</a>, <a href="#Class:_Feed">Feed</a></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_Feed">Class: Feed</h2>
+<p>represent availability of a dataset as a feed.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Class:</th><th><a href="http://www.w3.org/ns/dcat#Feed">dcat:Feed</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Usage note:</td><td>Describe the feed using <a href="#Property:_access.2Fdownload"> accessUrl</a>, <a href="#Property:_format" format</a> and <a href="#Property:_size"> size</a>. Further description of the web service is out the scope of dcat.</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Class:_Distribution">Distribution</a>, <a href="#Class:_Download">Download</a>, <a href="#Class:_WebService">WebService</a></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_Category_and_category_scheme">Class: Category and category scheme</h2>
+<p>The knowledge organization system (KOS) used to represent themes/categories of datasets in the catalog.</p>
+
+<table class="definition">
+ <thead><tr><th>RDF Classes:</th><th><a href="http://www.w3.org/2004/02/skos/core#ConceptScheme">skos:ConceptScheme</a>, <a href="http://www.w3.org/2004/02/skos/core#Concept">skos:Concept</a></th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Usage note:</td><td>It's necessary to use either skos:inScheme or skos:topConceptOf on every skos:Concept otherwise it's not clear which concept scheme they belong to.</td></tr>
+ <tr><td class="prop">See also:</td><td><a href="#Property:_themes">catalog themes</a>, <a href="#Property:_theme.2Fcategory">dataset theme</a></td></tr>
+ </tbody>
+</table>
+
+<h2 id="Class:_Organization.2FPerson">Class: Organization/Person</h2>
+
+<table class="definition">
+ <thead><tr><th>RDF Classes:</th><th><a href="http://xmlns.com/foaf/0.1/Person">foaf:Person</a> for people and <a href="http://xmlns.com/foaf/0.1/Organization">foaf:Organization</a> for government agencies or other entities.</th></tr></thead>
+ <tbody>
+ <tr><td class="prop">Usage note:</td><td><a href="http://xmlns.com/foaf/spec/">FOAF</a> provides sufficient properties to describe these entities.</td></tr>
+ </tbody>
+</table>
+
+<h2 id="Extending_the_vocabulary">Extending the vocabulary</h2>
+<ul>
+ <li> As with all RDF models, the model can be extended simply by using additional RDF properties anywhere. Catalog operators may choose from properties in existing vocabularies, or create their own custom vocabulary.</li>
+ <li> Additional classes, from existing or new vocabularies, can also be used.</li>
+ <li> Extensions used in a particular catalog should be documented to make users of the data aware of the additional available properties.</li>
+ <li> Creating new subclasses and subproperties of terms used in dcat, such as new types of distributions, is generally discouraged because it can break SPARQL queries that data consumers use to query the data.</li>
+ <li> As always with RDF, if you need to introduce new classes or properties, <em>do not introduce new terms in existing namespaces owned by someone else</em>, but set up your own namespace and define new terms in that namespace.</li>
+</ul>
+
+
+</body></html>