Interpret material value separately from evidence and fit
For material-use and repair questions, the default is a qualified ordinal judgement. A numeric 0–5 rendering is optional. A selected C.2.8 structural amount instead uses its own qualitative comparison, count, fraction or other justified structural scale; the following material-quality labels neither measure that amount nor set its threshold. When using the 0–5 material rendering, bind the following meanings to the exact property, material grain, task family, and support arrangement before applying them.
| Value | Material meaning for the declared use |
|---|---|
| 0 | The material demonstrably supplies no usable support for the required property, or defeats an explicitly declared non-compensable condition at this evaluation grain. |
| 1 | Some relevant support exists, but a material part of the promised work remains out of reach. |
| 2 | Useful work is recoverable, but repair must rebuild a connected central explanation–task chain or several consequential dependent uses. |
| 3 | The main work is recoverable; a bounded correction to the identified relation, task, representation, or return is still needed. |
| 4 | The property is adequate for the declared tasks, audience, and available support on the evidence required by the specification; no material defect is currently established for that use. |
| 5 | The property has defensible additional useful resilience across the specification’s consequential variations or boundary cases; the advantage and its evidence over 4 are stated. |
The numbers denote ordered meanings, not equal intervals. A severe local defect does not automatically make a whole book 0. Trace its effect on the declared task family and any actual non-compensable condition. A high average cannot compensate a failed condition that the use cannot trade away.
A floor belongs to the consuming decision, not to HCD as a whole. The Time-use S1 example in HCD.18 chooses 4 for each selected property before relying on its bounded supported introduction. That is a local rule. A diagnostic, controlled probe, or different consequence can require a different decision without changing what a value means.
Evidence accompanies the value. Source inspection, an actual reader attempt, conditional inference, disputed criterion, and an unobserved contribution are different grounds. Wrong object kind is a fit decision before invocation. A required coordinate that cannot be judged returns its explicit evidence or criterion defect and the conclusion it blocks. It does not disappear from a complete result and does not receive 0 for ignorance.
For an assigned value, explain why adjacent alternatives would understate or overstate the evidence. Distinguish a central connected repair from a bounded one by the changes needed in use, not error count. A value of 5 requires useful resilience beyond 4; actual manufacturing or repair history is additional evidence only when a historical claim is live. A value of 4 can still have a worthwhile improvement. Compare that improvement’s benefit with its cost and protected contributions.
Earlier evaluations under other specifications retain their original value meanings. For example, a local Guide scale whose 0 includes wrong kind or no basis is not numerically equivalent to this material scale. A comparison may relate “connected repair” to “bounded repair” while explicitly declining numeric conversion.