Expand description
PMI: dimensions, geometric tolerances, datums, their targets, and the drawing of them.
The machine-readable annotations AP242 calls semantic PMI: the values, not the leader lines. A dimension carries what it measures and its plus/minus bounds; a geometric tolerance carries its kind, magnitude and the datums it references; a datum is a letter on a feature, and its targets are the pads a fixture actually contacts it at. Everything anchors to topology nodes, the same way colours and names do, so an annotation survives every placement of the shape it describes.
And the presentation kind, which is the leader lines: where each
annotation is drawn, in which plane, as which polylines. It is kept
separate because it is separate: a drawing places its callouts where a
draughtsman put them, and neither half derives from the other. What ties
them is Callout::annotates, and a document may carry either alone.
Structs§
- Callout
- One drawn annotation: the geometry a viewer puts on the screen.
- Datum
- A datum: a letter naming a feature other annotations reference.
- Datum
Target - One datum target: which datum, which target of it, and where.
- Dimension
- A dimensional characteristic: a size or a location, with its values.
- Geometric
Tolerance - A geometric tolerance: flatness, position, profile, and their kin.
- Pmi
- A document’s PMI, in file order: the semantic annotations, the targets a datum is actually contacted at, and the drawn presentation.
Enums§
- Annotated
- Which semantic annotation a callout draws.
- Datum
Target Kind - Where a datum is actually contacted: the target a fixture touches it at.
- Measure
Kind - What a dimension’s value measures.