IfcCartesianPoint
Definition from ISO/CD 1030342:1992: A point defined by its coordinates in a two or three dimensional rectangular Cartesian coordinate system, or in a two dimensional parameter space. The entity is defined in a two or three dimensional space.
Definition from IAI: The derived attribute Dim has been added (see also note at IfcGeometricRepresentationItem). The WR1 was added to constrain the usage of IfcCartesianPoint in the context of IFC geometry. For the purpose of defining geometry in IFC only two and three dimensional Cartesian points are used.
NOTE Corresponding STEP entity : cartesian_point, please refer to ISO/IS 1030342:1994, p. 23 for the final definition of the formal standard. This complies to the Note in ISO/IS 1030342:1994.
HISTORY New class in IFC Release 1.0
EXPRESS specification:

Coordinates  :  The first, second, and third coordinate of the point location. If placed in a two or three dimensional
rectangular Cartesian coordinate system, Coordinates[1] is the X coordinate, Coordinates[2] is the Y
coordinate, and Coordinates[3] is the Z coordinate. 
Dim  :  The space dimensionality of this class, determined by the number of coordinates in the List of Coordinates. 
WR1  :  Only two or three dimensional points shall be used for the purpose of defining geometry in this IFC Resource. 
Name  Type  Referred through  ExpressG 
IfcCartesianTransformationOperator  Entity 

Diagram 4 
IfcLine  Entity 

Diagram 5 
IfcPlacement  Entity 

Diagram 3 
IfcPoint  Entity 

Diagram 3 
IfcPolyline  Entity 

Diagram 5 
IfcTrimmingSelect  Select 

Diagram 6 
