8.20.3.5 IfcEdgeCurve
8.20.3.5.1 Semantic definition
An IfcEdgeCurve defines two vertices being connected topologically including the geometric representation of the connection.
Informal Propositions
 The domain of the edge curve is formally defined to be the domain of its edge geometry as trimmed by the vertices. This domain does not include the vertices.
 An edge curve has nonzero finite extent.
 An edge curve is a manifold.
 An edge curve is arcwise connected.
 The edge start is not a part of the edge domain.
 The edge end is not a part of the edge domain.
 Vertex geometry shall be consistent with edge geometry.
8.20.3.5.2 Entity inheritance
8.20.3.5.3 Attributes
#  Attribute  Type  Description 

IfcRepresentationItem (2)  
LayerAssignment  SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems 
Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items. 

StyledByItem  SET [0:1] OF IfcStyledItem FOR Item 
Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve. 

IfcEdge (2)  
1  EdgeStart  IfcVertex 
Start point (vertex) of the edge. 
2  EdgeEnd  IfcVertex 
End point (vertex) of the edge. The same vertex can be used for both EdgeStart and EdgeEnd. 
Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes  
IfcEdgeCurve (2)  
3  EdgeGeometry  IfcCurve 
The curve which defines the shape and spatial location of the edge. This curve may be unbounded and is implicitly trimmed by the vertices of the edge; this defines the edge domain. Multiple edges can reference the same curve. 
4  SameSense  IfcBoolean 
This logical flag indicates whether (TRUE), or not (FALSE) the senses of the edge and the curve defining the edge geometry are the same. The sense of an edge is from the edge start vertex to the edge end vertex; the sense of a curve is in the direction of increasing parameter. 
8.20.3.5.4 Examples
8.20.3.5.5 Formal representation
ENTITY IfcEdgeCurve
SUBTYPE OF (IfcEdge);
EdgeGeometry : IfcCurve;
SameSense : IfcBoolean;
END_ENTITY;