{
  "case_id": "NYSE-2018-12-05-CLOSURE",
  "license": "CC0-1.0 derived metadata; no market-price records",
  "scope": "NYSE Group markets named in the official ICE/NYSE notice",
  "fact": {
    "date": "2018-12-05",
    "status": "closed",
    "source_id": "ICE-NYSE-BUSH-CLOSURE",
    "source_url": "https://ir.theice.com/press/news-details/2018/New-York-Stock-Exchange-to-Honor-President-George-H-W-Bush/default.aspx"
  },
  "engineering_assumption": {
    "naive_weekday_core_session_local": "09:30-16:00 America/New_York",
    "slot_minutes": 5,
    "half_open_interval_utc": "[2018-12-05T14:30:00Z, 2018-12-05T21:00:00Z)"
  },
  "derivation": {
    "naive_slots": 78,
    "official_calendar_slots": 0,
    "classification_for_each_naive_missing_slot": "closed_session",
    "arithmetic": "390 session minutes / 5 minutes = 78"
  },
  "provider_observation": null,
  "interpretation": "A weekday-only grid would manufacture 78 apparent gaps; the official closure evidence removes them from the expected universe."
}