ISO 19108:2002

Overview

ISO 19108:2002 - Geographic information - Temporal schema defines a standardized conceptual schema for describing the temporal characteristics of geographic information. The standard focuses on the abstraction of time as it applies to geographic features and datasets, emphasizing valid time (real-world time semantics) rather than transaction or system time. It provides a common foundation for temporal feature attributes, temporal operations, feature associations, and the temporal elements of metadata used in GIS, geospatial modelling, simulation and spatiotemporal analysis.

Key topics and requirements

• Temporal conceptual schema: formal structure for representing time-related aspects of geographic information, including how time is modelled as a dimension.
• Geometry of time: definitions of temporal objects, temporal geometric primitives, and temporal topological objects to express intervals, instants and relations in time.
• Temporal reference systems: description of different reference types (calendars, clocks, temporal coordinate systems, ordinal systems) and how to reference positions in time.
• Temporal position: concepts such as TM_Position and TM_TemporalPosition for expressing temporal coordinates and references (calendar/clock or coordinate system referenced).
• Temporal feature modelling: guidance on temporal feature attributes, temporal feature operations, and feature associations that involve time (e.g., succession, recurring values).
• Temporal metadata: requirements for documenting temporal reference systems and temporal metadata elements (Annex C normative).
• Conformance and testing: five conformance classes and an Abstract Test Suite in Annex A (normative) that specify conformance requirements for application schemas, feature catalogues, metadata specs and datasets.
• Informative guidance: Annex B covers practical use of time in application schemas; Annex D explains calendar descriptions and examples.

Practical applications and users

ISO 19108 is practical for:

• GIS software developers implementing temporal data types, temporal queries and spatiotemporal models.
• Data modelers and geospatial architects designing temporal feature attributes, temporal topologies and feature lifecycles.
• Metadata specialists documenting temporal reference systems and dataset temporal extents for discovery and interoperability.
• Organizations performing time-based analyses: simulations, predictive modelling, moving-object tracking, environmental monitoring, cadastral history and temporal change detection.
• Standards bodies and integrators ensuring interoperability between systems that exchange temporal geographic information.

Related standards and integration

ISO 19108 depends on and complements other standards, notably ISO 8601 for date/time formats and other ISO/TC 211 standards in the ISO 19100 series (spatial schema, conceptual schema language, rules for application schema). It establishes the temporal foundation for future spatiotemporal standards and interoperable GIS data exchange.

Keywords: ISO 19108, temporal schema, geographic information, temporal reference systems, temporal metadata, valid time, GIS, spatiotemporal, temporal position.