8.9.3.1 IfcAxis1Placement

8.9.3.1.1 Semantic definition

The IfcAxis1Placement provides location and direction of a single axis.

Figure 8.9.3.1.A illustrates the definition of the IfcAxis1Placement within the parent three-dimensional coordinate system.

8.9.3.1.2 Entity inheritance

8.9.3.1.3 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. 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.
IfcPlacement (2)
1	Location	IfcPoint	The geometric position of a reference point, such as the center of a circle, of the item to be located.
*	Dim	IfcDimensionCount	This attribute is formally derived. `Location.Dim` The space dimensionality of this class, derived from the dimensionality of the location.
Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes
IfcAxis1Placement (2)
2	Axis	OPTIONAL IfcDirection	The direction of the local Z axis.
*	Z	IfcDirection	This attribute is formally derived. `NVL (IfcNormalise(Axis), IfcRepresentationItem() \|\| IfcGeometricRepresentationItem () \|\| IfcDirection([0.0,0.0,1.0]))` The normalized direction of the local Z axis. It is either identical with the Axis value, if given, or it defaults to [0.,0.,1.]

Table 8.9.3.1.B

8.9.3.1.4 Formal propositions

Name	Description
AxisIs3D	The Axis when given should only reference a three-dimensional IfcDirection.
`(NOT (EXISTS (Axis))) OR (Axis.Dim = 3)`
LocationIs3D	The Cartesian point defining the Location shall have the dimensionality of 3.
`SELF\IfcPlacement.Location.Dim = 3`
LocationIsCP	No description available.
`'IFC4X3.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location)`

Table 8.9.3.1.C

8.9.3.1.5 Formal representation

ENTITY IfcAxis1Placement
 SUBTYPE OF (IfcPlacement);
	Axis : OPTIONAL IfcDirection;
 DERIVE
	 Z : IfcDirection := NVL (IfcNormalise(Axis), IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,0.0,1.0]));
 WHERE
	AxisIs3D : (NOT (EXISTS (Axis))) OR (Axis.Dim = 3);
	LocationIs3D : SELF\IfcPlacement.Location.Dim = 3;
	LocationIsCP : 'IFC4X3.IFCCARTESIANPOINT' IN TYPEOF(SELF\IfcPlacement.Location);
END_ENTITY;