Transit anomalies: ship transits at straits and canals against their usual level

Costs 3 token(s) per request (a flat amount — the minimum of a page of signals). Takes no parameters: every strait and canal where ship transits are measured (28 places — Hormuz, Suez, Bab el-Mandeb, Malacca, Bosporus, Panama, Taiwan Strait and others) is returned in one response, the places outside their usual range first. A transit anomaly is a measurement, not a report. Each place carries status — usual, below or above its usual range, or not_measured — and level, an index computed by this product: the 7-day average of ship transits with the usual level set to 100 (index), the change against usual (change, 0.05 = +5%), the same index for tankers alone (tanker_index), and revised when the underlying figure changed after it was first recorded. Ship counts are not returned. Usual level: the median of the 7-day averages over the 12 weeks before. A 7-day average is outside its usual range when it is statistically unusual against those weeks (modified Z-score of 3.5 or more) and at least 15% away. meta.definition carries the same sentence. While a place is outside its usual range, anomaly gives the direction, since (the first day of the current unbroken run, looking back 30 days), days, and event_id — the event recorded for it, the same id GET /api/v1/signals returns with categories=transit_anomaly (measured=true, measured_kind=transit), so the event endpoints work on it; null when no event is linked. entity_id is the registry id GET /api/v1/entities/{entityId} takes, which returns the recent levels of one place. It never states a cause: weather, holidays, a closure, an attack and re-routing all change the number of ships. The measure comes from ship tracking (AIS) signals and covers container, dry bulk, general cargo, ro-ro and tanker ships, so ships that do not broadcast, and other kinds of vessel, are not counted. The underlying measurements are updated weekly, so a change becomes visible 4 to 11 days after it happens; meta.as_of is the latest day measured. The numbers (index, change, tanker_index, revised) need a plan with the full event detail. Without it every place still returns its status, anomaly and event_id, with detail_withheld=true and null in those fields (meta.detail_included and meta.detail_required_plan say so).