additions  where_rules  LocationIs2D 
additions  where_rules  RefDirIs2D 
deletions  where_rules  WR1 
deletions  where_rules  WR2 
additions  where_rules  LocationIsCP 
The IfcAxis2Placement2D provides location and orientation to place items in a twodimensional space. The attribute RefDirection defines the x axis, the y axis is derived. If the attribute RefDirection is not given, the placement defaults to P[1] (xaxis) as [1.,0.] and P[2] (yaxis) as [0.,1.].
Figure 1 illustrates the definition of the IfcAxis2Placement2D within the twodimensional coordinate system. 

Figure 1 — Axis2 placement 2D 
NOTE Definition according to ISO/CD 1030342:1992
The location and orientation in two dimensional space of two mutually perpendicular axes. An axis2_placement_2d is defined in terms of a point, (inherited from the placement supertype), and an axis. It can be used to locate and originate an object in two dimensional space and to define a placement coordinate system. The entity includes a point which forms the origin of the placement coordinate system. A direction vector is required to complete the definition of the placement coordinate system. The reference direction defines the placement X axis direction, the placement Y axis is derived from this.NOTE Entity adapted from axis2_placement_2d defined in ISO 1030342.
HISTORY New entity in IFC1.5.
#  Attribute  Type  Description 

IfcRepresentationItem  
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. > IFC2x3 CHANGE The inverse attribute LayerAssignments has been added. > IFC4 CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.  
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. > IFC2x3 CHANGE The inverse attribute StyledByItem has been added.  
IfcGeometricRepresentationItem  
IfcPlacement  
1  Location  IfcPoint  The geometric position of a reference point, such as the center of a circle, of the item to be located. 
Dim  INVALID  The space dimensionality of this class, derived from the dimensionality of the location.  
IfcAxis2Placement2D  
2  RefDirection  OPTIONAL IfcDirection  The direction used to determine the direction of the local X axis. If a value is omited that it defaults to [1.0, 0.0.]. 
P  INVALID  _P[1]_: The normalized direction of the placement X Axis. This is [1.0,0.0] if RefDirection is omitted. _P[2]_: The normalized direction of the placement Y Axis. This is a derived attribute and is orthogonal to P[1]. If RefDirection is omitted, it defaults to [0.0,1.0] 
ENTITY IfcAxis2Placement2D SUBTYPE OF (IfcPlacement); RefDirection : OPTIONAL IfcDirection; DERIVE P : LIST [2:2] OF IfcDirection := IfcBuild2Axes(RefDirection); WHERE RefDirIs2D : (NOT (EXISTS (RefDirection))) OR (RefDirection.Dim = 2); LocationIs2D : SELF\IfcPlacement.Location.Dim = 2; LocationIsCP : 'IFC4X3_DEV_a1492713.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location); END_ENTITY;