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Data Model

The TRF data model is intentionally simple: artifacts describe evidence, links express relationships, and auxiliary files capture provenance, signatures, and attachments. This section formalizes those structures.

Artifact structure​

{
  "id": "req:ACC-001",
  "kind": "requirement",
  "version": "2.1.0",
  "status": "approved",
  "created_at": "2024-01-15T10:00:00Z",
  "created_by": {
    "name": "Jane Smith",
    "email": "jane.smith@example.com"
  },
  "fields": {
    "title": "Maintain safe distance",
    "acceptance_criteria": ["Activation within 200ms"],
    "priority": "high",
    "asil": "D"
  },
  "attachments": [
    {
      "path": "attachments/requirements/acc.pdf",
      "hash": "sha256:..."
    }
  ]
}
  • id – Namespaced identifier (prefix + semantic name).
  • kind – Core type or extension type; drives schema validation.
  • fields – Arbitrary JSON following the schema definition for the kind.
  • attachments – Optional list referencing files within the package.
{
  "id": "link:REQ-VER-001",
  "from": "req:ACC-001",
  "to": "test:TC-ACC-001",
  "relation": "verified_by",
  "confidence": 1.0,
  "rationale": "Regression suite covers all acceptance criteria",
  "fields": {
    "review_id": "CR-4821"
  }
}
  • relation values come from core or extension-defined vocabularies.
  • confidence (0–1) captures certainty; defaults to 1 when omitted.
  • fields holds extra metadata (review IDs, evidence URLs, change tickets).

Manifest​

{
  "twpack_version": "2.0.0",
  "schema_version": "2.0.0",
  "name": "ACC safety case",
  "description": "Quarterly release evidence",
  "profile": "automotive_safety",
  "extensions": ["automotive", "cybersecurity"],
  "artifact_count": 642,
  "link_count": 1584,
  "generated_at": "2024-03-31T18:22:00Z",
  "generator": {
    "name": "tw-cli",
    "version": "2.1.0"
  }
}

The manifest also hosts optional statistics (coverage metrics, domain summaries) and references to external schemas.

Signatures​

{
  "package_signature": {
    "algorithm": "RSA-SHA256",
    "timestamp": "2024-03-31T18:25:00Z",
    "signer": "build-system@example.com",
    "certificate": "..."
  },
  "artifact_signatures": [
    {
      "artifact_id": "req:ACC-001",
      "hash": "sha256:...",
      "signer": "requirements-lead@example.com",
      "timestamp": "2024-03-30T09:10:00Z"
    }
  ]
}

Signatures are optional but recommended in multi-organization workflows.

Attachments​

  • Stored under attachments/ with any directory structure.
  • Lines in attachments.jsonl (optional) can record MIME type, size, or additional metadata.
  • Artifacts reference attachments using relative paths and hashes.

Schema inheritance​

  • Core schemas define fields for requirement, test, design, component.
  • Extension schemas extend core definitions using allOf inheritance rules (JSON Schema Draft 2020-12).
  • Custom schemas can be placed in schemas/custom/ and referenced through configuration.

Referencing multiple packages​

  • Artifact IDs may include pack prefixes (supplierA:req:ACC-001) when merging supplier evidence.
  • Links can reference external packs via external_to fields or by embedding supplier packs (embedded_packs in the manifest).

For practical examples, examine the sample packs in the TRF repository or continue to Architecture Overview and Framework Versioning.