{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Chronology event",
  "type": "object",
  "required": ["date_text", "event", "sources"],
  "properties": {
    "date_text": {"type": "string"},
    "date_normalized": {"type": ["string", "null"], "format": "date"},
    "event": {"type": "string"},
    "sources": {"type": "array", "items": {"type": "string"}},
    "certainty": {"enum": ["explicit", "uncertain", "not_identified"]}
  },
  "additionalProperties": false
}