ISO 10303-214:2010(E)
An Instance_placement is the information pertaining to the placement of a Single_instance, which is defined in its own Cartesian_coordinate_space, in the coordinate space of a reference Product_component.
NOTE A Product_component may be placed by a transformation, using Model_property_association.
The data associated with an Instance_placement are the following:The placed_instance specifies the Single_instance that is placed.
The coordinate system is defined by any
Geometric_model or
External_geometric_model representing the shape of the placed_instance .
The Geometric_model or External_geometric_model that is referred to, indirectly, by
Instance_placement.placement and which defines the local geometry of the Single_instance shall be associated with the
Single_instance through an instance of
Shape_description_association and of
Item_shape.
NOTE If the shape of the Item_instance is not different from the shape of the Design_discipline_item_definition referred to by the instance of Item_shape the Geometric_model representing this shape is shared.
See instance_placement to single_instance for the application assertion.
The placement specifies the Geometric_model_relationship_with_transformation or the Template_instance that defines the position of the 'placed_instance' relatively to the 'reference_product_component'. In the case of Template_instance, the scale shall be omitted or set to 1.0.
The Geometric_model associated with the 'reference_product_component', in which the Geometric_model or External_model of the placed instance is located, shall contain Axis_placement instances locating each placed instance and may contain additional instances of geometric entities, describing shape aspects relevant in the context of the 'reference_product_component'.
EXAMPLE The Geometric_model associated with a reference_product_component 'car engine' may contain Axis_placement instances locating the gear box and the crankshaft and additional geometric information representing the envelope box allowed for the car engine.
See instance_placement to geometric_model_relationship_with_transformation and instance_placement to template_instance for the application assertions.
There shall be exactly one object that defines the placement for an Instance_placement.
The reference_product_component specifies the Product_component that specifies indirectly the reference coordinate space. The coordinate system of the reference_product_component that serves as a reference for the placement shall be specified by an External_geometric_model or a Geometric_model referenced by a Model_property_association. The 'definition' of the Model_property_value shall be a General_property with a 'property_type' of 'positioning'. Alternatively the coordinate system is defined by the shape of the reference_product_component .
See instance_placement to product_component for the application assertion.
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