1. Source
Use official or clearly licensed public data and retain source URL, release date and provenance.
Methodology
Every claim should be reproducible.
The product is built around a strict pipeline. If the evidence is not comparable, we publish nothing.
2. Vintage
Store the value as it appeared in a specific publication release rather than silently replacing history.
3. Comparability gate
Require the same entity, indicator, reference period, compatible unit and validated methodology.
4. Deterministic calculation
Revision size, direction and histories are calculated by code. LLMs do not invent numerical facts.
5. Evidence object
One canonical object feeds human HTML, JSON, CSV and structured metadata so outputs cannot drift.
6. Publication
Stable URLs expose raw values, calculation, method, update timestamp and source attribution.
MVP rule: demo values stay visibly labelled as demo until a real archived release passes provenance and methodology validation.