Open vocabulary

Sport is full of proprietary names for simple arithmetic. Intero uses plain words that describe what is computed, none of them a trademark, and it doesn't borrow anyone else's. Anyone can use these words to describe the same things.

Training load

Work: Mechanical energy from a power meter: average power × time. Stored in joules (J), shown in kilojoules (kJ). Cycling only; power on a run comes from a device's model, not a meter, and is refused.
Heart-rate load: Session time weighted by how far average heart rate sits between resting and maximum: T · x · 0.64 · e^(1.92·x), with x the heart-rate reserve fraction. The constants are a published exponential-reserve convention, not fitted to anyone. Stored in weighted seconds, shown in weighted minutes, with a band from the uncertainty in resting and maximum heart rate.
Acute convention: An exponentially weighted average of daily load with a time constant of 7 days. A convention, not a personal model: individual time constants were found not to be identifiable from the data.
Chronic convention: The same average with a time constant of 42 days.
Unknown weight: The share of an acute or chronic value that rests on days with no measurement. Unknown days are never zero; above a 10% share the value is refused.
Possible duplicate: A session that may be the same activity recorded by two sources. It is listed, never merged, and only widens the upper end of a day's band, so one ride is never counted twice.
Rest day: A day inside the recorded span with no session: an exact zero. A day outside it, or in a long gap, is unknown, not zero.

Sensor Court

Witness: One device's reading of one metric for one night.
Sensor passport: What is known about a witness: vendor, device, metric definition, and era.
Era and epoch: An era is a device or firmware period the data reveals; an epoch is a stretch inside one where the court detected the bias shifting. Each gets its own calibration.
Wake date: The date a night belongs to: the day you woke up, in the time zone you were in.
Verdict: The court's fused estimate for a metric and night.
Band: The 80% range around a verdict. It widens with each device's noise and with disagreement between devices.
Overruled: A witness that sat too far from the others to be believed, set aside with the numbers that decided it.
Refusal: A typed answer in place of a number, with a reason and a receipt. Drawn hatched.
Receipt: The input readings, their passports, the algorithm, its version and parameters behind a claim.
Claim: One entry in the append-only, hash-chained ledger: a value or a refusal, with its receipt.
Own baseline: Your own recent verdicts summarised as a centre and spread, with an effective sample size that accounts for nights not being independent.
Settlement: The moment a forecast meets the observation it named, and is scored.

Words Intero avoids

No proprietary training-stress, normalised-power or intensity-factor names, and no "fitness, fatigue, form" model. A guard test in the code base fails the build if those names appear. Wording stays descriptive: Intero never promises how you will feel or recover.

Metric names and units are defined once, in the metric registry.