{"rules_version":"1","fields":{"confidence_label":"high | medium | low — how much evidence stands behind the value or answer.","coverage_label":"ready | partial | gap — how much of the question the value or answer covers.","label_basis":"The inputs (source_type, verification_age_days, stale, and for answers the series read) and the rule ids that fired, in words."},"applies_to":["Every series read: GET /v1/{country}/{series} (incl. ?as_at=), /v1/{country}/{series}/history (top level and each entry), /v1/all, /public/{country}/holidays, /v1/certified/{country}/{series}.","Every computed answer that reaches its engine: POST /v1/answers/* and POST /v1/vat/determine, including honest no-answer statuses (HTTP 200 or 422).","/catalog series entries (labels only, no label_basis).","The MCP tools that return those responses, in structuredContent and declared in each tool's outputSchema.","Not on validation refusals (400/404, or a 422 'error' body refused before payment): those are not answers."],"series_confidence":[{"id":"C1","rule":"Start from the source type (`confidence` field): primary → high; derived → high; secondary → medium; attested → low; absent → treated as primary (as /catalog does)."},{"id":"C2","rule":"No citation URL on the value → low."},{"id":"C3","rule":"Current value only: stale (days since last_confirmed > update_cycle_days) → one step down."},{"id":"C4","rule":"Current value only: last verified more than 365 days ago, or last_confirmed unreadable → low."},{"id":"C5","rule":"Derived series: never higher than the label of the reference series it is computed from."}],"series_coverage":[{"id":"G1","rule":"Null headline with no breakdown (withholding_rates, registration_thresholds, wage_schedule, vat_bands, rates, subdivisions, variants): gap when the notes open with REFUSAL / WHY REFUSED, or the series is listed under no_single_figure (the instrument exists but no single current number is correct); otherwise ready (an explained absence — the instrument does not exist, and null is the answer).","no_single_figure":{"br/vat":"Brazil levies ICMS, ISS, IPI and PIS/COFINS, with CBS/IBS in a test year — there is no single VAT rate.","in/minimum-wage":"India's minimum wages are fixed by the Centre and each state, by schedule — there is no single national figure.","vu/minimum-wage":"Vanuatu has a national minimum wage, but no current figure could be verified."}},{"id":"G2","rule":"Value held but effective_from null (commencement unknown) → partial."},{"id":"G3","rule":"A dated list (e.g. holidays) with entries that are provisional or have no date yet → partial."},{"id":"G4","rule":"Breakdown entries with no figure (wage_schedule value null, withholding rate null) → partial. A null registration threshold means 'register regardless' and does not count."},{"id":"G5","rule":"coverage_limit.covered_to already passed → partial; otherwise informational only."},{"id":"-","rule":"Anything else → ready."}],"answer_confidence":[{"id":"A1","rule":"The lowest confidence_label among the series the computation read. No graded series input: medium on a computed answer, low on a no-answer status."}],"answer_coverage":[{"id":"A2","rule":"Engine status: ok or no_statutory_minimum → ready; not_comparable → partial; any other status (not_computable, no_single_rate, unsupported, out_of_scope, unknown_subdivision, …) → gap."},{"id":"A3","rule":"A ready answer becomes partial when it rests on a default it discloses: wage-check general floor assumed; VAT standard rate assumed with other bands available; working days outside the published holiday calendar; income-tax default rate table among variants; statutory interest headline among several margins; Nigeria payroll without pay composition; employment-cost schemes refused; settlement cycle caller-asserted; cross-border VAT with an unidentified buyer (B2C default)."},{"id":"A4","rule":"A ready answer that reads a series whose coverage_label is gap becomes partial."}],"invariants":["Additive: no existing field changes meaning. `confidence` remains the source type; `stale` is unchanged.","Labels are derived only from fields already in the response or the series it was computed from; nothing new is asserted.","Answer receipts sign the same result subset as before; labels are not in the signed receipt. Certified extracts carry the labels inside the signed value block as well as at top level."],"docs":"https://usaref.dev/docs"}