Parent for Every Record

Context#

Above the requirements the hierarchy is rationale prose rather than required links, and the book teaches a second hierarchy beside the model's own.

Decision#

Every record of every type has exactly one parent: by identifier containment, by one required written up-link, or, for a type with no record above it, its layer list under the product. A missing required parent is an error at tier G. Every inverse link is computed, never written.

Evidence with Confidence#

research/behavior-containment-evidence and research/intent-hierarchy-evidence are measured over the largest consumer on 2026-10-30, high confidence. research/book-outline-evidence is read from the builder source, high confidence on placement, medium on full-size behavior since the sample is partial. research/established-traceability-practice carries the stated vendor-restatement limit.