DCAT US 3.0

DCAT-US 3.0 is Data.gov's incoming metadata standard, replacing DCAT-US 1.1 (the 2014 Project Open Data schema). It is a JSON Schema 2020-12 implementation of the W3C DCAT v3 vocabulary, maintained at GSA/dcat-us. The authoritative field-level documentation lives at resources.data.gov/resources/dcat-us3.

Why it exists

• Overcomes v1.1's spatial/geospatial limits without needing a separate federal geospatial standard
• Adds first-class support for data services (APIs) and dataset series (recurring publications)
• Adds controlled-vocabulary support (Concept/ConceptScheme) instead of bare strings for theme/category
• Closely related to v1.1: new elements added, no major rework of existing ones

Status

• harvest.data.gov supports dcatus3.0 as a harvest source schema_type; sources go straight to VALIDATE, same as 1.1 (no TRANSFORM step needed)
• Harvester public validator is live and supports DCAT-US3.0 catalogs (https://harvest.data.gov/validate/)

Key structural differences from 1.1

• Root Catalog gets a service[] array (DataService) alongside dataset[], as well as a datasetSeries[] array (DatasetSeries), plus optional record[] (CatalogRecord) and nested catalog[]/hasPart[]
• contactPoint goes from a single vCard to a Kind object or a list of them
• theme/category go from bare strings to Concept objects, optionally scoped to a ConceptScheme
• spatial goes from a free string to a Location object (geometry/bbox/centroid/prefLabel)
• New top-level classes: DatasetSeries (recurring publications), DataService (APIs), CatalogRecord (catalog registration metadata), Concept/ConceptScheme (controlled vocabularies)

For the full field-by-field diff against 1.1, see DCAT-US 1.1 vs 3.0.

Notable spec design points

• CatalogRecord's @id has no declared requirement level, so a spec-valid record can have no identifier of its own; it is primaryTopic and modified that carry the meaning.
• spatial (Location) can represent geography four different ways: geometry, bbox, centroid, or prefLabel. A given record may populate any subset of them.
• Series membership can be dual: a dataset may legitimately appear both as a top-level catalog.dataset entry and as a DatasetSeries.seriesMember. It is preferred to only list as a datasetSeries.seriesMember

Official documentation

• DCAT-US 3.0 overview and per-class schema reference (Catalog, Dataset, Distribution, DatasetSeries, Agents, Temporal/Spatial/Metrics, Identifiers and Relationships, Quality and Governance, Constraints and Restrictions), resources.data.gov
• Quick migration guide, 1.1 → 3.0, resources.data.gov
• M-25-05 crosswalk, maps OMB Memorandum M-25-05's required metadata elements to DCAT-US 3.0 classes/properties
• DCAT-US 3 tools, schedule, and maintenance plan, resources.data.gov
• DCAT-US 1.1 reference (legacy), resources.data.gov

Source & schema reference

• Spec + JSON Schema: GSA/dcat-us
• Generated field docs: jsonschema/docs
• 1.1 → 3.0 conversion script, fetches a v1.1 catalog and converts it to a validated v3.0 catalog
• Local schema checkout: datagov-harvester/_external/dcat-us/ (git submodule)
• v1.1 schemas for comparison: datagov-harvester/schemas/dcatus1.1/
• Fixtures for both versions: datagov-harvester/example_data/dcatus/