# Vlada ontology layer one (identifier)

`vlada_ontology.l1_identifier` · Curated datasets · status live · 4,716 rows

The Vlada ontology, layer one (who holds and who owns every Medicare, Medicaid and Marketplace instrument, over time), SIGNED by Ben on build v3o (2026-10-28; docs/architecture/ontology-v2/L1-SIGNOFF.md). Permanent IDs; a legal entity is not its brand nor the contract it holds; history is dated events with filings; every fact graded A/B/C with its evidence; two clocks. Built by tools/ontology2/build.py, served by tools/ontology2/serve.py (the view moves only to a signed build). Tools: resolve_entity, describe_entity; API: /v1/entities.

**Grain.** One row per identifier that names an entity: namespace (cms_org_name, ein, naic, cik, hios, ...), value, value_norm, validity window, evidence.

| column | type | meaning |
|---|---|---|
| entity_id | string |  |
| namespace | string |  |
| value | string |  |
| value_norm | string |  |
| valid_from | string |  |
| valid_to | string |  |
| evidence_id | string |  |

Tools that read it: describe_entity, resolve_entity

Query it: `query_substrate` with `SELECT ... FROM vlada_ontology.l1_identifier WHERE ... LIMIT 100`; read `describe_data_source("vlada_ontology.l1_identifier")` first.