| Prefix | URI | Description | For more details see | Origin |
|---|---|---|---|---|
| xml | http://www.w3.org/XML/1998/namespace | XML Reserved Prefix | Namespaces in XML 1.0 | W3C Recommendation |
| xmlns | http://www.w3.org/2000/xmlns/ | XMLNS Reserved Prefix | Namespaces in XML 1.0 | W3C Recommendation |
| xsd | http://www.w3.org/2001/XMLSchema# | XML Schema Datatypes | XML Schema Part 2: Datatypes Second Edition | W3C Recommendation |
| rdf | http://www.w3.org/1999/02/22-rdf-syntax-ns# | RDF | RDF Semantics | W3C Recommendation |
| rdfs | http://www.w3.org/2000/01/rdf-schema# | RDF Schema | RDF Semantics | W3C Recommendation |
| owl | http://www.w3.org/2002/07/owl# | OWL | OWL Overview | W3C Recommendation |
| rif | http://www.w3.org/2007/rif# | RIF | RIF Overview | W3C Recommendation |
| skos | http://www.w3.org/2004/02/skos/core# | SKOS Core | SKOS Simple Knowledge Organization System Reference | W3C Recommendation |
| skosxl | http://www.w3.org/2008/05/skos-xl# | SKOS eXtension for Labels | SKOS Simple Knowledge Organization System Reference | W3C Recommendation |
| grddl | http://www.w3.org/2003/g/data-view# | GRDDL | Gleaning Resource Descriptions from Dialects of Languages (GRDDL) | W3C Recommendation |
| rdfa | http://www.w3.org/ns/rdfa# | RDFa Vocabulary | RDFa Core 1.1 | W3C Recommendation |
| wdr | http://www.w3.org/2007/05/powder# | POWDER | Protocol for Web Description Resources (POWDER): Formal Semantics | W3C Recommendation |
| wdrs | http://www.w3.org/2007/05/powder-s# | POWDER-S | Protocol for Web Description Resources (POWDER): Formal Semantics | W3C Recommendation |
| sioc | http://rdfs.org/sioc/ns# | SIOC Core Ontology | SIOC Core Ontology Specification | W3C Member Submission |
| cc | http://creativecommons.org/ns# | ccREL | ccREL: The Creative Commons Rights Expression Language | W3C Member Submission |
| vcard | http://www.w3.org/2006/vcard/ns# | vCard in RDF | Representing vCard Objects in RDF | W3C Member Submission |
| Term | URI | Description | For more details see | Origin |
|---|---|---|---|---|
| describedby | http://www.w3.org/2007/05/powder-s#describedby | XML Reserved Prefix | POWDER: Formal Semantics, Section 5, POWDER Processor Semantics | W3C Recommendation |