{
  "version": "1.0",
  "grain": "One metric observation per entity, period, population and source revision",
  "key": [
    "entity_id",
    "metric",
    "period",
    "population",
    "source_revision"
  ],
  "fields": {
    "entity_id": "STRING required; use canonical source IDs where available",
    "entity_name": "STRING required",
    "metric": "STRING required; defined in metric dictionary",
    "value": "NUMERIC nullable; never coerce missing or suppressed to zero",
    "unit": "STRING required for numerical observation",
    "period": "STRING required; do not mix academic and fiscal years",
    "population": "STRING required; comparable denominator definition",
    "source_url": "HTTPS required",
    "source_revision": "STRING required; source release or pinned receipt",
    "retrieved_at": "TIMESTAMP UTC required",
    "evidence_state": "STRING: synthetic, source_checked, independently_verified",
    "missing_reason": "STRING nullable: missing, suppressed, not_applicable, incomparable"
  },
  "ranking": "No default composite score; disclose weights, exclusions, ties and missingness before ranked output."
}