info-tech-canon/demand/EvidenceBasis.md

Demand: Evidence Basis — how a quantity was obtained, and how far a conclusion may be trusted

Status: accepted (canon 0.4.0) Date: 2026-08-15 Source: resource-control (consumer), domain financials Owner: ITC-GOV (Evidence), imported by ITC-CAP CapabilityConsumption (CAP-R10) Requested by: info-tech-canon, in reply to the ITC-CAP restatement, 2026-08-15 Consumer implementation: resource-control/tools/basis.py, docs/evidence-basis.md Workplan: ITC-WP-0015 Catalog: infospace/models/governance/evidence-basis.yaml

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Demand signal

ITC-GOV §11.34 defines Evidence as "information used to support a claim", with examples that are all artifact kinds: a log extract, a scan result, a test result, a deployment record. §11.35 defines an Assertion as a claim that something is true, supported by evidence.

Nothing in the canon says how a quantity was obtained, and therefore nothing bounds how far a conclusion computed from it may be trusted.

That is a different question from which artifact supports a claim. An artifact can be impeccable while the number inside it is a guess. A consumer reading two numbers of the same shape — 7.35 and 60.00 — cannot tell that one is a published price and the other is an assumed hour count multiplied by an assumed rate, and the canon currently gives it no way to say so.

Why this cannot stay private to one consumer

resource-control has implemented and is running this. We are filing rather than keeping it because the same argument info-tech-canon accepted for CapabilityConsumption applies unchanged: a private vocabulary diverges the moment a second repository reports evidence-bearing quantities.

It is already wanted in three places on the consumer side alone — capability consumption rows, monthly actual observations, and threshold evaluations. That breadth is also why the concept should not live in ITC-CAP: it is not about capabilities. It is about quantities, wherever they occur.

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Proposed concepts

EvidenceBasis

A closed, ordered vocabulary naming how a single quantity was obtained.

Basis	Meaning
invoiced	Taken from an authoritative financial record
measured	Directly observed from the authoritative system
quoted	Stated by a provider or counterparty in a citable source
derived	Computed from other values by a stated rule
projected	Interpolated between, or extrapolated beyond, observations
estimated	Human judgement, neither observed nor computed
assumed	A modelling constant chosen by the author
unknown	No value exists

invoiced, measured, and quoted are evidenced: they assert an observed or contracted fact. Everything below is inference.

On invoiced. Per info-tech-canon's own instruction, this names a fin-hub fact rather than originating one. The basis says only where a value came from; it does not define booked-cost, tax, or currency semantics, which stay with the financial authority under its own exchange contract.

Strength is a tier, not a total order. invoiced and measured are peers. An invoice is authoritative for a payment and a measurement is authoritative for a quantity; neither outranks the other outside its own domain. The consumer's first implementation got this wrong by using a strict list order, and corrected it — weakest(["invoiced", "measured"]) must not imply a difference that does not exist.

derived_from and the propagation rule

A derived value is only as strong as the weakest value it was computed from.

This is the rule that earns the vocabulary its place. Without it, arithmetic launders assumptions: a two-decimal euro figure reads like a measurement when it is an assumed hour count times an assumed rate.

A derived value carries derived_from, the values it was computed from, and resolves to the weakest of them, recursively. Derivation is not penalised in itself: GB computed from measured bytes resolves to measured.

unknown carries no quantity

A value with basis unknown MUST NOT carry a quantity, and MUST name the gap and the party who owns it. A value with any other basis MUST carry a quantity. Zero means "measured and none"; unknown means "not measured". Both directions should be enforced, because the failure mode runs both ways — a missing amount silently read as zero, and a zero mistaken for an absence.

proxy_for

An orthogonal qualifier: the value is a genuine measurement of a different quantity than the one being reasoned about. It does not weaken the measurement; it weakens the inference drawn from it. A shared-database allocation driver may measure bytes precisely while one of those databases has never recorded a transaction.

DecisionGrade

A rollup over the values a conclusion rests on — an Assertion whose strength is bounded by its weakest supporting value.

Grade	Condition
evidenced	Every load-bearing value is invoiced, measured, or quoted
projected	The conclusion rests on values projected from observations
indicative	The conclusion is no stronger than an estimated or assumed value
insufficient	At least one load-bearing value is unknown

This is the seam to existing ITC-GOV vocabulary: Evidence supports an Assertion; a DecisionGrade states how far that support actually reaches.

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Worked evidence from the consumer

The mechanism was applied to the consumer's own most consequential decision — the provider selection that produced its backup resource, a €29.14 per month difference stated to the cent:

by_basis         {quoted: 1, projected: 1, assumed: 2}
weakest          assumed
evidenced_ratio  0.25
grade            indicative

One of four load-bearing values is evidenced. The two labour figures — the ones that actually inverted the provider ranking — are each derived from an assumed hour count and an assumed rate, so both resolve to assumed.

The finding did not overturn the decision: the direction is robust under any plausible rate. It did establish that the magnitude is a model output rather than a measurement, and it identified the cheapest way to strengthen it — record real operator hours, not refine the arithmetic.

A mechanism whose first act is to qualify its author's own headline number is behaving correctly.

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Proposed placement

Owner: ITC-GOV. EvidenceBasis, derived_from and its propagation rule, the unknown rule, proxy_for, and DecisionGrade sit beside Evidence, Assertion, and Attestation in §11.34–11.36. They describe the epistemic status of information, which is ITC-GOV's ground.

Import: ITC-CAP. CapabilityConsumption gains an evidence basis per row. It already distinguishes unknown from zero, which is the same discipline applied to presence; basis applies it to the values that are present. CAP-R8 would be joined by a rule that a consumption row declares its basis.

Also imports: ITC-OBS (a measurement is measured; a modelled series is projected), and any model carrying quantities that consumers compare.

Avoid: defining this only in ITC-CAP. It is not about capabilities, and scoping it there would force a second, incompatible vocabulary the first time a non-capability quantity needs grading.

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Success criteria

1. A closed basis vocabulary with tiers, not a spurious total order.
2. A stated propagation rule for derived values, computable and testable.
3. Unknown carries no quantity and names its gap and owner; zero is a measurement.
4. proxy_for expressible and orthogonal to strength.
5. Decision grades defined against existing Assertion semantics.
6. CapabilityConsumption imports the basis without ITC-CAP owning it.
7. resource-control can drop its private vocabulary in favour of the canon's without changing any recorded value.

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Non-goals

• Booked-cost, tax, or currency semantics. invoiced names a financial fact; it does not define one.
• A confidence interval, probability, or statistical error model. Basis is categorical provenance, not quantified uncertainty. A value may be measured and still be a single noisy sample — age and sample size are separate qualifiers and the canon should not conflate them with basis.
• A data-quality scoring or maturity scheme for datasets.
• An automated inference of basis. It is declared by the author of the value.