--- /dev/null
+<?php
+
+/**
+ * @file
+ * Hooks provided by the RDF module.
+ */
+
+/**
+ * @addtogroup hooks
+ * @{
+ */
+
+/**
+ * Allow modules to define namespaces for RDF mappings.
+ *
+ * Many common namespace prefixes are defined in rdf_rdf_namespaces(). However,
+ * if a module implements rdf mappings that use prefixes that are not
+ * defined in rdf_rdf_namespaces(), this hook should be used to define the new
+ * namespace prefixes.
+ *
+ * @return string[]
+ * An associative array of namespaces where the key is the namespace prefix
+ * and the value is the namespace URI.
+ *
+ * @ingroup rdf
+ */
+function hook_rdf_namespaces() {
+ return [
+ 'content' => 'http://purl.org/rss/1.0/modules/content/',
+ 'dc' => 'http://purl.org/dc/terms/',
+ 'foaf' => 'http://xmlns.com/foaf/0.1/',
+ 'og' => 'http://ogp.me/ns#',
+ 'rdfs' => 'http://www.w3.org/2000/01/rdf-schema#',
+ 'sioc' => 'http://rdfs.org/sioc/ns#',
+ 'sioct' => 'http://rdfs.org/sioc/types#',
+ 'skos' => 'http://www.w3.org/2004/02/skos/core#',
+ 'xsd' => 'http://www.w3.org/2001/XMLSchema#',
+ ];
+}
+
+/**
+ * @} End of "addtogroup hooks".
+ */