# 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.