A07 · Reference edition 2026.11
Datum reference frames — Layout and sequence
The drawing datum scheme and the physical fixture are related descriptions, not interchangeable objects. Datum precedence affects the intended setup.
Scope and purpose
Place the relevant elements in a visible order before completing the record. A diagram should distinguish position from sequence and should preserve the orientation used in the written notes. Review the example for a practical way to make the relationship explicit.
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 |
|---|---|
| A07 | 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
Identify the starting condition; mark the order or orientation; check that labels in the figure match the accompanying table.