IfcAnnotationCurveOccurrence

Definition from ISO/CD 10303-46:1992: An annotation curve occurrence is a curve with a style assignment.

> NOTE Corresponding STEP name: annotation_curve_occurrence. Please refer to ISO/IS 10303-46:1994 for the final definition of the formal standard.

Definition from IAI: The IfcAnnotationCurveOccurrence shall only be used within a material or paper space dependent representation (note: paper space is not yet supported within this IFC release). Styled curves within model space shall use IfcStyledItem as the instance to link the geometric curve representation item to the (shared) style information.

An IfcAnnotationCurveOccurrence is a relation object, that assigns a (set of) styles to a representation item. It can be used without having a geometric representation item already assigned, e.g. within an IfcMaterialDefinitionRepresentation. If it has a geometric representation item already assigned than this is further restricted to be a subtype of IfcCurve. The applicable style information is restricted to be an IfcCurveStyle. For each instance of a styled curve, one instance of IfcAnnotationCurveOccurrence has to be created, that points, via an IfcPresentationStyleAssignment, to an IfcCurveStyle, that can be shared by many styled curves.

> HISTORY New entity in Release IFC2x Edition 2.

EXPRESS specification:

ENTITY IfcAnnotationCurveOccurrence
SUBTYPE OF ( | IfcAnnotationOccurrence);
WHERE
WR31 | : | NOT(EXISTS(SELF\IfcStyledItem.Item)) OR ('IFCGEOMETRYRESOURCE.IFCCURVE' IN TYPEOF (SELF\IfcStyledItem.Item));
END_ENTITY;

Formal Propositions:

WR31 | : | The Item that is styled by an IfcAnnotationCurveOccurrence relation shall be (if provided) a subtype of IfcCurve. NOTE If no Item is provided, the IfcAnnotationCurveOccurrence is used to provide a curve style to a material dependent presentation.

Inheritance graph

ENTITY IfcAnnotationCurveOccurrence;
ENTITY IfcRepresentationItem;
INVERSE
LayerAssignments | : | SET OF IfcPresentationLayerAssignment FOR AssignedItems;
StyledByItem | : | SET [0:1] OF IfcStyledItem FOR Item;
ENTITY IfcStyledItem;
Item | : | OPTIONAL IfcRepresentationItem;
Styles | : | SET [1:?] OF IfcPresentationStyleAssignment;
Name | : | OPTIONAL IfcLabel;
ENTITY IfcAnnotationOccurrence;
ENTITY IfcAnnotationCurveOccurrence;
END_ENTITY;