W3CThe vCard Ontology bridges the well-established vCard contact information standard with the Semantic Web by providing an OWL mapping of vCard properties into RDF classes and properties. This allows contact data for people and organizations to be published, shared, and queried as linked data while remaining compatible with traditional vCard implementations.
Background
The vCard specification has a long history in the contact information domain, originating in 1995 and first standardized by the IETF in 1998 as RFC 2426. An initial RDF representation of vCard was published as a W3C Member Submission covering vCard 3.0. When the IETF significantly updated vCard to version 4 with RFC 6350, the RDF mapping required a corresponding update.
The current vCard Ontology was developed by Renato Iannella (Semantic Identity) and James McKinney (OpenNorth) under the Semantic Web Interest Group. It was published as a W3C Interest Group Note on 22 May 2014 and provides a complete mapping from RFC 6350 to OWL.
Purpose & Scope
The ontology maps all major sections of the vCard specification into Semantic Web representations:
- General Properties -- source, kind, and XML representations
- Identification Properties -- formatted name, name components, nicknames, photos, birthdays, anniversaries, and gender
- Delivery Addressing Properties -- structured and unstructured addresses
- Communications Properties -- telephone, email, and instant messaging
- Geographical Properties -- timezone and geographic coordinates
- Organizational Properties -- organization name, title, role, logo, and organizational relationships
- Explanatory Properties -- categories, notes, URLs, keys, and sound
- Security and Calendar Properties -- encryption keys, calendar URIs, and free/busy information
The ontology uses a naming convention where OWL object properties follow a "hasX" pattern (for resources identified by URIs) and data properties use just the "x" pattern (for literal values). An n-ary relationship mechanism supports vCard's property parameters such as sort-as, geographic location, and type annotations.
Key Classes
| Class | Description |
|---|---|
| Individual | A single person |
| Organization | An organization or company |
| Group | A group of people or organizations |
| Location | A named geographical location |
| Kind | The parent class for vCard entity types |
| Address | A structured postal address |
Serializations & Technical Formats
The ontology continues to use the namespace URI http://www.w3.org/2006/vcard/ns# from the previous W3C Member Submission to support backward compatibility. This namespace also serves a JSON-LD context. The ontology can be serialized in RDF/XML, Turtle, and JSON-LD.
Governance & Maintenance
The vCard Ontology is published by the W3C Semantic Web Interest Group. As an Interest Group Note, it does not carry the same normative weight as a W3C Recommendation but represents consensus within the interest group. The specification is freely available under the W3C Document License.
Notable Implementations
The vCard Ontology is used within government linked data initiatives, organizational directories, and contact information services that publish data as RDF. It complements FOAF (which focuses on social relationships) and the W3C Organization Ontology (which focuses on organizational structures). The three ontologies can be used collaboratively: vCard for detailed contact information, FOAF for social network relationships, and ORG for organizational hierarchies.
Related Standards
- FOAF focuses on relationships between people, agents, and social entities, with some overlap in contact description.
- W3C Organization Ontology describes organizational structures, roles, and activities, complementing vCard's contact details.
- RFC 6350 is the underlying IETF specification that this ontology maps to RDF.