Metadata Schema
Definition
A metadata schema is the structured set of fields, vocabularies, and rules that define how metadata should be recorded for datasets, services, or maps. Examples include ISO 19115/19139 for geospatial datasets, Dublin Core for general resources, INSPIRE profiles in the EU, and project-specific schemas for internal catalogs. A schema dictates mandatory vs. optional fields, controlled vocabularies for topics and licenses, and encoding formats (XML, JSON, YAML). Well-designed schemas balance rigor with usability, enabling consistent discovery and interoperability across tools. They evolve with organizational needs; governance processes manage changes without breaking backward compatibility. Schemas also facilitate validation and automated quality checks in CI pipelines. Provide explicit methods, QA notes, and version history so others can reuse the layer responsibly. Provide explicit methods, QA notes, and version history so others can reuse the layer responsibly. Embedding schema validation in CI means broken records never get published. Examples and style guides reduce free-text ambiguity and improve search results.
Application
National Spatial Data Infrastructures adopt schemas to standardize publication. Companies implement lightweight schemas for internal data stores. Research groups use schemas to ensure that code notebooks can programmatically access lineage and parameters for reproducibility. Geoportals rely on schemas to power search facets and APIs.
FAQ
How do we choose between ISO and a custom schema?
Use ISO for interoperability and external sharing; layer a simplified profile for internal use if ISO feels heavy. Provide mappings both ways.
What’s the role of controlled vocabularies?
They prevent ambiguous tags and improve search. Adopt existing vocabularies (GEMET, GCMD) or define clear in-house lists where needed.
How do we enforce schema quality?
Automated validators in publishing pipelines, required fields in forms, and periodic audits. Provide examples and templates to reduce friction.
Can schemas change over time?
Yes—version them. Provide migration guides and tools so old records remain useful while new fields become available.