#### 8.7.3.9 IfcCurve

| Courbe
| Kurve

An IfcCurve is a curve in two-dimensional or three-dimensional space. It includes definitions for bounded and unbounded curves.

> NOTE Definition according to ISO 10303-42:
> A curve can be envisioned as the path of a point moving in its coordinate space.

> NOTE Entity adapted from curve defined in ISO 10303-42

> HISTORY New entity in IFC1.0

Informal Propositions:

1. A curve shall be arcwise connected
2. A curve shall have an arc length greater than zero.

XSD Specification:

<xs:element name="IfcCurve" type="ifc:IfcCurve" abstract="true" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>
<xs:complexType name="IfcCurve" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:IfcGeometricRepresentationItem"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcCurve

| ABSTRACT SUPERTYPE OF(ONEOF(IfcBoundedCurve, IfcLine))

| SUBTYPE OF (IfcGeometricRepresentationItem);

| DERIVE

Dim | : | IfcDimensionCount := IfcCurveDim(SELF);

END_ENTITY;

Attribute Definitions:

Dim | : | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.

Inheritance Graph:

ENTITY IfcCurve

| ENTITY IfcRepresentationItem

| INVERSE

LayerAssignment | : | SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems;
StyledByItem | : | SET [0:1] OF IfcStyledItem FOR Item;

| ENTITY IfcGeometricRepresentationItem

| ENTITY IfcCurve

| DERIVE

Dim | : | IfcDimensionCount := IfcCurveDim(SELF);

END_ENTITY;

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