A08 · Reference edition 2026.11
Datum reference frames — Comparison and alternatives
The drawing datum scheme and the physical fixture are related descriptions, not interchangeable objects. Datum precedence affects the intended setup.
Scope and purpose
Compare alternatives using the same question and context. A difference in wording, layout or scale is not automatically a difference in performance. Keep the original observations available and explain which differences are meaningful for this comparison.
Working notes
This reference collection concerns light, offline dimensional-inspection layouts. It brings locating concepts, component descriptions and revision records together without substituting for an engineered fixture design. The drawings are original explanatory diagrams. Reference IDs identify documents, not commercially tested products. Read the scope and limitations alongside each example, and keep the actual part drawing and inspection requirements available when reviewing a proposed layout.
Practical example
Place the drawing reference beside each contact group and mark which face is loaded first.
| Reference record | Interpretation |
|---|---|
| A08 | Datum reference frames |
| Scope and purpose | The drawing datum scheme and the physical fixture are related descriptions, not interchangeable objects. Datum precedence affects the intended setup. |
| Limits and interpretation | A convenient flat face is not automatically a specified datum feature. |
Review checklist
State the comparison question; align context and labels; list common features separately from differences; leave unsupported conclusions open.