IFC 4.3.1.0 (IFC4X3_ADD1) development

8.18.3.2 IfcCoordinateReferenceSystem

ABSTRACT This definition may not be instantiated

8.18.3.2.1 Semantic definition

The IfcCoordinateReferenceSystem is a definition of a coordinate reference system by means of qualified identifiers only. The interpretation of the identifier is expected to be well-known to the receiving software.

The unambiguous identifier by which the coordinate reference system is know, is stored in the Name attribute. Well defined identifiers include the geodetic and often also the vertical datum. In these cases the GeodeticDatum and the VerticalDatum can be omitted.

8.18.3.2.2 Entity inheritance

8.18.3.2.3 Attributes

# Attribute Type Description
IfcCoordinateReferenceSystem (4)
1 Name OPTIONAL IfcLabel

Name by which the coordinate reference system is identified.

2 Description OPTIONAL IfcText

Informal description of this coordinate reference system

Example for ellipsoid: ELLIPSOID[,,,]

HasCoordinateOperation SET [0:1] OF IfcCoordinateOperation FOR SourceCRS

Indicates conversion between coordinate systems. In particular it refers to an IfcCoordinateOperation between this coordinate reference system, and another Geographic coordinate reference system.

WellKnownText SET [0:1] OF IfcWellKnownText FOR CoordinateReferenceSystem

Well Known Text (WKT) definition for this Coordinate Reference System inversely associated as a IfcWellKnownText entity.

Table 8.18.3.2.A

8.18.3.2.4 Formal propositions

Name Description
NameOrWKT

No description available.

(HIINDEX(WellKnownText) = 1) OR EXISTS(Name)
Table 8.18.3.2.B

8.18.3.2.5 Formal representation

ENTITY IfcCoordinateReferenceSystem
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcGeographicCRS
	,IfcProjectedCRS));
	Name : OPTIONAL IfcLabel;
	Description : OPTIONAL IfcText;
 INVERSE
	HasCoordinateOperation : SET [0:1] OF IfcCoordinateOperation FOR SourceCRS;
	WellKnownText : SET [0:1] OF IfcWellKnownText FOR CoordinateReferenceSystem;
 WHERE
	NameOrWKT : (HIINDEX(WellKnownText) = 1) OR EXISTS(Name);
END_ENTITY;

8.18.3.2.6 References

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8.18.3.2.7 Changelog

8.18.3.2.7.1 IFC4

  • New resource

8.18.3.2.7.2 IFC4.3_DEV_9f90c1f0

  • inverse attribute, WellKnownText
  • where rule, NameOrWKT
  • attribute, GeodeticDatum
  • attribute, VerticalDatum
  • attribute Name optional, Changed from "False" to "True"