C.21:5.2 - Measurement, comparison, or aggregation

Open C.16 when an actual measurement is claimed. Make the DHC replay basis recoverable, identify measurement Work and result separately, and apply A.18 legality. For direct comparison use the same-semantics branch in section 4.2. For a comparison that relies on a cross-local semantic relation, add the exact F.9 branch. Open G.0, A.19, normalization, distance, evidence-reliance, or assurance only when the operation or receiver actually consumes it.