W3C
OGCOWL-Time is a formal OWL-2 DL ontology of temporal concepts, jointly published by W3C and OGC. It provides a vocabulary for describing the temporal properties of resources, focusing on topological ordering relations among instants and intervals, together with durations and temporal positions. The ontology supports not only the conventional Gregorian calendar-clock system but also alternative temporal reference systems including Unix time, geologic time, and non-Gregorian calendars.
Background
The origins of OWL-Time date to a 2006 Working Draft by Jerry R. Hobbs and Feng Pan, which established the core ontology for temporal concepts. The Spatial Data on the Web Working Group (a joint W3C-OGC initiative) subsequently revised and extended the ontology, with editors Simon Cox (CSIRO) and Chris Little (Met Office). The current document is a W3C Candidate Recommendation Draft dated 15 November 2022, carrying OGC Document Number 16-071r3. The specification document was completely rewritten from the 2006 draft.
Purpose and Scope
Temporal information is critical in most real-world applications -- from online orders and car rentals to scientific monitoring and transactional systems. OWL-Time provides the formal vocabulary needed to:
- Describe ordering relationships between temporal entities (based on Allen's 13 interval relations)
- Express time positions using various reference systems and calendars
- Describe durations in both structured and compact (xsd:duration) forms
- Support vernacular names for months and days
- Associate temporal entities with any resource via a generic
time:hasTimepredicate
Key Classes
The ontology defines 18 classes:
| Class | Description |
|---|---|
| TemporalEntity | Superclass of Instant and Interval |
| Instant | A zero-duration temporal entity |
| Interval | A temporal entity with extent |
| ProperInterval | An interval with non-zero duration |
| DateTimeInterval | An interval described by start/end date-times |
| Duration | Superclass for duration descriptions |
| DurationDescription | Duration in calendar-clock terms |
| GeneralDurationDescription | Duration using any temporal reference system |
| TemporalDuration | Duration as a scaled value |
| DateTimeDescription | Position in Gregorian calendar-clock terms |
| GeneralDateTimeDescription | Position using any calendar |
| TemporalPosition | Position on a temporal reference system |
| TimePosition | Numeric or nominal temporal position |
| DayOfWeek | Named day |
| MonthOfYear | Named month |
| TemporalUnit | Unit for duration measurement |
| TimeZone | Timezone specification |
| TemporalReferenceSystem | A system for temporal measurement |
Key Properties
The 58 properties include Allen's interval relations (intervalBefore, intervalAfter, intervalContains, intervalDuring, intervalEquals, intervalOverlaps, intervalMeets, intervalStarts, intervalFinishes, and their inverses), date-time component accessors (year, month, day, hour, minute, second), duration accessors, and XSD datatype mappings.
Serializations and Namespace
- Namespace:
http://www.w3.org/2006/time#(prefix:time) - Gregorian individuals:
http://www.w3.org/ns/time/gregorian# - Available in Turtle and RDF/XML at the namespace URI
Governance and Maintenance
Developed by the Spatial Data on the Web Working Group. The 2022 revision added support for non-Gregorian calendars, hasXSDDuration, MonthOfYear, and hasTime. IANA link relation types have been registered for the interval relations.
Notable Implementations
OWL-Time is used in geospatial data infrastructures, scientific observation metadata, provenance tracking, and any linked data application requiring formal temporal reasoning. It provides alignment with W3C PROV-O temporal concepts.
Related Standards
- SSN/SOSA (sosa-ssn): Commonly used together for temporal annotation of sensor observations