# Traceability Matrix (TM)

One matrix per project: `docs/sqa/traceability-matrix.md`. It makes the
Business Case's cross-artifact traceability target measurable.

## Required sections (after Metadata / Version History)

- **Purpose**.
- **Traceability Table** — one row per artifact instance:
  `Artifact Instance | Type | Language | Domain | Upstream (Backward Link) |
  Downstream (Forward Link) | Last Reviewed (RC-ID)`. `Language` and `Domain`
  copy the artifact's Metadata rows so a reviewer can pick the right reviewer
  from the matrix; they are `-` for a technical type (OC, SD, DCD, ERD, ADR,
  TM, RC, QC, source code). `check-languages.sh --list` prints the same values.
  Add or update a row whenever an instance is created or reviewed.
- **Coverage Notes** — which types have no instance yet, and how to read
  `-`: in Upstream it means foundational; in Downstream it means nothing
  is built on it yet; in Last Reviewed it means no `RC-*` exists yet.