In-play statistics for one match, in TWO families that are deliberately not merged.

DERIVED (the top level of players.pN) are rebuilt from the point-by-point record: service and return games played and won, hold and break percentage, break points faced, saved and converted, service and return points.

MEASURED (players.pN.measured) are counted upstream, so they include what no point record can yield — ACES AND DOUBLE FAULTS, the first- and second-serve split, winners and unforced errors. Both families name some of the same quantities, computed two entirely different ways; that is a cross-check, not a duplication to collapse.

Measured coverage is not uniform and every measured field is optional — an absent field is OMITTED, never zero-filled, so read the keys you are given. Aces and double faults are present across every tour. The serve split and break points saved are present on the main tours and absent on ITF singles. Winners and unforced errors historically appeared on a minority of main-tour matches and have not been delivered upstream since 2026-07-12 (measured 2026-08-17).

freshness.derived and freshness.measured each carry their own coverage (live | final | stale | none | diverged; final = the closing figures of a completed match — a finished match cannot be "stale", so its age_seconds is null), as_of, age_seconds and describes — the match state the numbers describe. On diverged the measured VALUES are withheld and freshness.measured_divergence says why; the top-level coverage only summarises the response. none on both returns 200 with null players, not 404 — the match exists and holding nothing for it is the honest answer.

THE TWO AGES USE DIFFERENT CLOCKS AND MUST NOT BE COMPARED. The derived age is measured against the newest SCORE row, because between points there is no new score either and wall-clock age would report staleness that does not exist. The measured age is wall clock, because those are fetched on a fixed cadence.

Tiebreak games are excluded from the DERIVED family and counted separately; the live record collapses a whole tiebreak onto one entry, so most of its points are lost.