# Vlada ontology layer one (event)

`vlada_ontology.l1_event` · Curated datasets · status live · 565 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 sourced corporate event: acquisition, merger, formation, transfer of business, divestiture, rename, with announced and closed dates, buyer and targets.

| column | type | meaning |
|---|---|---|
| event_id | string |  |
| type | string |  |
| status | string |  |
| announced | string |  |
| closed | string |  |
| buyer | string |  |
| targets | string |  |
| label | string |  |
| evidence_id | string |  |
| recorded_version | string |  |

Tools that read it: describe_entity, resolve_entity

Query it: `query_substrate` with `SELECT ... FROM vlada_ontology.l1_event WHERE ... LIMIT 100`; read `describe_data_source("vlada_ontology.l1_event")` first.