This list of predefined prefixes have been defined for RDFa as an “initial context”: essentially, RDFa users can use these prefixes without having the obligation of defining the prefixes in the HTML code. The same list of prefixes have also been defined for JSON-LD as a JSON-LD Context at the URI http://www.w3.org/2013/json-ld-context/rdfa11; JSON-LD users can use the @context key with that URI as a shorthand to use the same prefixes.
| Prefix | URI | Description | For more details see | Origin |
|---|---|---|---|---|
| as | https://www.w3.org/ns/activitystreams# | Activity Vocabulary | Activity Vocabulary | W3C Recommendation |
| csvw | http://www.w3.org/ns/csvw# | Metadata for Tabular Data | Metadata Vocabulary for Tabular Data | W3C Recommendation |
| dcat | http://www.w3.org/ns/dcat# | Data Catalog Vocabulary | Data Catalog Vocabulary (DCAT) | W3C Recommendation |
| dqv | http://www.w3.org/ns/dqv# | Data Quality Vocabulary | Data on the Web Best Practices: Data Quality Vocabulary | W3C WG Note |
| duv | https://www.w3.org/ns/duv# | Dataset Usage Vocabulary | Dataset Usage Vocabulary | W3C WG Note |
| grddl | http://www.w3.org/2003/g/data-view# | GRDDL | Gleaning Resource Descriptions from Dialects of Languages (GRDDL) | W3C Recommendation |
| jsonld | http://www.w3.org/ns/json-ld# | JSON-LD | JSON-LD 1.1, A JSON-based Serialization for Linked Data | W3C Recommendation |
| ldp | http://www.w3.org/ns/ldp# | Linked Data Platform Vocabulary | Linked Data Platform 1.0 | W3C Recommendation |
| ma | http://www.w3.org/ns/ma-ont# | Ontology for Media Resources | Ontology for Media Resources 1.0 | W3C Recommendation |
| oa | http://www.w3.org/ns/oa# | Web Annotation Vocabulary | Web Annotation Vocabulary | W3C Recommendation |
| odrl | http://www.w3.org/ns/odrl/2/ | ODRL Vocabulary & Expression 2.2 | ODRL Vocabulary & Expression 2.2 | W3C Recommendation |
| org | http://www.w3.org/ns/org# | Organizations | The Organization Ontology | W3C Recommendation |
| owl | http://www.w3.org/2002/07/owl# | OWL | OWL Overview | W3C Recommendation |
| prov | http://www.w3.org/ns/prov# | Provenance Vocabulary | Provenance Ontology | W3C Recommendation |
| qb | http://purl.org/linked-data/cube# | Data Cubes | The RDF Data Cube Vocabulary | W3C Recommendation |
| rdf | http://www.w3.org/1999/02/22-rdf-syntax-ns# | RDF | RDF Semantics | W3C Recommendation |
| rdfa | http://www.w3.org/ns/rdfa# | RDFa Vocabulary | RDFa Core 1.1 | W3C Recommendation |
| rdfs | http://www.w3.org/2000/01/rdf-schema# | RDF Schema | RDF Semantics | W3C Recommendation |
| rif | http://www.w3.org/2007/rif# | RIF | RIF Overview | W3C Recommendation |
| rr | http://www.w3.org/ns/r2rml# | R2RML | R2RML: RDB to RDF Mapping Language | W3C Recommendation |
| sd | http://www.w3.org/ns/sparql-service-description# | SPARQL 1.1 Service Description | SPARQL 1.1 Service Description | 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 |
| ssn | http://www.w3.org/ns/ssn/ | Semantic Sensor Network Ontology | Semantic Sensor Network Ontology | W3C Recommendation |
| sosa | http://www.w3.org/ns/sosa/ | Sensor, Observation, Sample, and Actuator Ontology | Semantic Sensor Network Ontology | W3C Recommendation |
| time | http://www.w3.org/2006/time# | Time Ontology | Time Ontology in OWL | W3C Recommendation |
| void | http://rdfs.org/ns/void# | VoID | Describing Linked Datasets with the VoID Vocabulary | W3C Interest Group Note |
| 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 |
| xhv | http://www.w3.org/1999/xhtml/vocab# | RDFa Default Prefix | RDFa Core 1.1 | W3C Recommendation |
| xml | http://www.w3.org/XML/1998/namespace | XML 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 |
Some vocabularies are currently in development at W3C and they may become W3C Recommendations or Notes, i.e., may become part of the table above. It is therefore advisable to consider their prefixes reserved for now. These are:
| Prefix | URI | Description | For more details see |
|---|---|---|---|
| cc | http://creativecommons.org/ns# | ccREL | ccREL: The Creative Commons Rights Expression Language |
| ctag | http://commontag.org/ns# | Common Tag Ontology | Common Tag Specification |
| dc | http://purl.org/dc/terms/ | Dublin Core Metadata Terms | DCMI Metadata Terms |
| dcterms | http://purl.org/dc/terms/ | Dublin Core Metadata Terms | DCMI Metadata Terms |
| dc11 | http://purl.org/dc/elements/1.1/ | Dublin Core Metadata Element Set, Version 1.1 | Dublin Core Metadata Element Set, Version 1.1 |
| foaf | http://xmlns.com/foaf/0.1/ | FOAF | FOAF Vocabulary Specification |
| gr | http://purl.org/goodrelations/v1# | GoodRelations Ontology | GoodRelations Language Reference |
| ical | http://www.w3.org/2002/12/cal/icaltzd# | iCalendar terms in RDF | iCalendar terms in RDF |
| og | http://ogp.me/ns# | Facebook's Open Graph protocol | Open Graph Protocol |
| rev | http://purl.org/stuff/rev# | RDF Review Vocabulary | RDF Review Vocabulary |
| sioc | http://rdfs.org/sioc/ns# | SIOC Core Ontology | SIOC Core Ontology Specification |
| v | http://rdf.data-vocabulary.org/# | Google Rich Snippets' Vocabularies | Rich snippets (microdata, microformats, and RDFa) |
| vcard | http://www.w3.org/2006/vcard/ns# | vCard in RDF | Representing vCard Objects in RDF |
| schema | http://schema.org/ | The Schema.org vocabulary | Full Schema.org documentation |
| Term | URI | Description | For more details see |
|---|---|---|---|
| describedby | http://www.w3.org/2007/05/powder-s#describedby | Refers to resource providing a description. | POWDER: Formal Semantics, Section 5, POWDER Processor Semantics |
| license | http://www.w3.org/1999/xhtml/vocab#license | Refers to a license associated with this context. | IANA Link Relations |
| role | http://www.w3.org/1999/xhtml/vocab#role | indicates the purpose of the resource. See the XHTML Role Vocabulary for roles in this vocabulary space | XHTML Role Attribute Module |