
    # Datum extraction

    **Skill ID:** `reverse_engineering_and_scanning.datum-extraction`  
    **Domain:** Reverse Engineering and Scanning  
    **Initial status:** Reading only; not certified for Forge.

    ## Purpose

    Teach SHiRE to apply **Datum extraction** as one part of a complete design workflow. This skill must be combined with requirements, safety, research, manufacturing and validation rather than used alone.

    ## Learning outcomes

    SHiRE must be able to:

    1. Explain when this skill is appropriate.
    2. Identify required inputs and missing evidence.
    3. Choose a repeatable, editable method.
    4. Detect likely failures.
    5. Define measurable acceptance criteria.
    6. preserve source provenance and licence status.
    7. Refuse, constrain or escalate unsafe use.

    ## Domain principles

    - Treat scans as uncertain evidence, not perfect truth.
- Calibrate scale and verify critical dimensions manually.
- Separate noisy surfaces from functional datums.
- Preserve raw, cleaned and aligned data plus transforms.
- Never use low-cost scans alone for medical fit or safety-critical geometry.

    ## Repeatable method

    1. Preserve the original dialog.
    2. Extract purpose, interfaces, dimensions, tolerances, environment and risk.
    3. Mark facts, measurements, retrieved evidence and assumptions separately.
    4. Search official and clearly licensed sources for current principles.
    5. Create a small safe practice example.
    6. Preserve editable source and named parameters.
    7. Test minimum, nominal, maximum and invalid cases.
    8. Record pass, fail, limitation and evidence paths.
    9. Keep Forge permission false until Academy certification passes.

    ## Common failures

    - Scale drift.
- Flipped or mirrored coordinates.
- Smoothing away features.
- Designing over scan holes.
- No manual cross-check.

    ## Practice exercises

    - Explain the skill through a safe household example.
    - Build a deliberately wrong example and diagnose it.
    - Build a parameterised example across minimum, nominal and maximum values.
    - Create a provenance record for every source.
    - Apply the skill in a multi-domain brief without bypassing safety.

    ## Certification

    - knowledge score at least 90 percent;
    - three completed practice projects;
    - one rejected example correctly diagnosed;
    - boundary and invalid tests;
    - provenance and licence review;
    - safety gate;
    - editable source and validation report;
    - no hidden blockers.

    ## Limitations

    This starter lesson defines a learning and evidence framework. It does not replace current standards, calibrated machine profiles, verified material data, physical testing or qualified professional review.
