Overview
EN ISO 19126:2021 - Geographic information - Feature concept dictionaries and registers (ISO 19126:2021) specifies a schema for establishing and managing feature concept dictionaries as registers. It clarifies how dictionaries that define the meaning and structure of geographic features are modeled, maintained and related to feature catalogues through a hierarchical register. The document aligns registers with ISO 19135‑1 (registration procedures) and supersedes earlier editions.
Key topics and technical requirements
- Scope and conformance
- Defines conformance rules for both a feature concept dictionary and for registers of dictionaries/catalogues.
- Feature concept dictionary schema
- Introduces core schema classes (prefixed with
CD_) such as CD_FeatureConceptDictionary, CD_Concept, CD_FeatureConcept, CD_FeaturePropertyConcept, CD_FeatureAttributeConcept, CD_NominalValueConcept, CD_ConceptRelationship and related types.
- Specifies requirements and properties for these classes to support consistent definition and exchange of feature concepts.
- Registers and register structure
- Specifies a schema for registers of feature concept dictionaries and a hierarchical register that can include feature catalogues (while not prescribing catalogue schemas).
- Covers register structure, compound registries, register management and registration metadata.
- Relationship to data products and application schemas
- Describes how dictionaries and registers relate to data product specifications and application schemas, enabling semantic interoperability.
- Notation, packages and community implementations
- Addresses notation and packaging conventions to support implementation, reuse and community-driven registries.
Applications and practical value
- Ensures consistent, machine-readable definitions of features and their properties for GIS datasets, national mapping agencies, utilities, environmental data, and spatial data infrastructures.
- Enables interoperability between feature catalogues, application schemas and software tools by providing a standard way to register and manage concept dictionaries.
- Supports data governance: versioning, registration, authoritative definitions, and reuse of nominal value lists (controlled vocabularies).
- Useful for geospatial software vendors, data stewards, GIS architects, standards bodies and any organization implementing metadata registries or spatial data services.
Who should use this standard
- GIS/data managers and registry administrators establishing authoritative concept dictionaries.
- Developers and integrators building application schemas, data product specifications or semantic validation tools.
- National mapping agencies, spatial data infrastructures (SDIs), utilities and environmental agencies seeking consistent feature semantics.
Related standards
- ISO 19135‑1 (registration procedures) - registers and registration management.
- Other ISO 19100 series standards for geographic information (application schemas, metadata and catalogues) for broader interoperability.
