F4:Position Validation
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Summary
F4 validates position against the ASME logic in the F4 Application and enforces feature-type, datum, modifier, and basic-dimension rules.
Validation rules
- Position requires a feature of size.
- Position is valid only for a planar feature of size or a cylindrical feature of size.
- Basic dimensions must be used to establish true position.
- Tangent plane and unequally disposed are not allowed.
- Planar FOS: diameter and projected tolerance zone are not allowed.
- Cylindrical FOS: diameter is required.
- A datum reference is required for planar FOS; cylindrical FOS can be allowed without a datum.
Warnings and errors
F4 behavior
- Invalid feature type
If the FCF is applied to anything other than a planar FOS or cylindrical FOS, F4 flags non-compliance.
F4 behavior
- Missing basic dimensions
Position requires basic dimensions to establish true position; missing basic dimensions are rejected.
F4 behavior
- Missing datum
Planar feature of size position requires at least one datum reference.
F4 behavior
- Missing diameter
Cylindrical feature of size position must include the diameter modifier.
F4 behavior
- Prohibited modifiers
Tangent plane, unequally disposed, and other prohibited modifiers are rejected.
Examples
- Valid: planar FOS position with basic dimensions and a datum reference.
- Valid: cylindrical FOS position with the diameter modifier.
- Invalid: missing basic dimensions or missing datum on planar FOS.