5.1.3.40 IfcRelDefinesByType

RV ⓘ

AbV ⓘ

5.1.3.40.1 Semantic definition

The objectified relationship IfcRelDefinesByType defines the relationship between an object type and object occurrences. The IfcRelDefinesByType is a 1-to-N relationship, as it allows for the assignment of one type information to a single or to many objects. Those objects then share the same object type, and the property sets and properties assigned to the object type.

The IfcRelDefinesByType links the object type definition with the object occurrence. Both may define properties by assigning an IfcPropertySet, including one or many subtypes of IfcProperty to either the object type or object occurrence, as shown in Figure 5.1.3.40.A.

There are several scenarios to define the same property set on the object type definition and object occurrence side:

All properties for all object occurrences of a common object type have the same value - then only the object type definition has a property set assigned.
All properties for all object occurrences are different, that is there are no common property values for the object type definition - then each of the object occurrences has a property set assigned.
Some properties within the same property set have common values and are assigned to the object type definition and some are occurrence specific and assigned (with potentially different values) to the object occurrences - then:
The sum of all properties within a given property set applicable to an object occurrence is the union of properties assigned to the object type definition plus the properties assigned to the object occurrence.
If the object occurrence has a property with the same IfcProperty.Name in an IfcPropertySet, as the corresponding object type definition, then the occurrence property value overrides the type property value.

instance diagram — Figure 5.1.3.40.A — Type definition relationships

The following table provides an example of assigning properties that can be overridden.

Properties assigned to IfcWallType	Property assigned to IfcWall	Resulting property value for individual wall
-	ExtendToStructure = TRUE	ExtendToStructure = TRUE
ThermalTransmittance = 0.375	-	ThermalTransmittance = 0.375
ExtendToStructure = TRUE	ExtendToStructure = FALSE	ExtendToStructure = FALSE

Table 5.1.3.40.U

5.1.3.40.2 Entity inheritance

- IfcRoot

5.1.3.40.3 Attributes

#	Attribute	Type	Description
IfcRoot (4)
1	GlobalId	IfcGloballyUniqueId	Assignment of a globally unique identifier within the entire software world.
2	OwnerHistory	OPTIONAL IfcOwnerHistory	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE Only the last modification is stored - either as addition, deletion or modification. IFC4-CHANGE The attribute has been changed to be OPTIONAL.
3	Name	OPTIONAL IfcLabel	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.
4	Description	OPTIONAL IfcText	Optional description, provided for exchanging informative comments.
Click to show 4 hidden inherited attributes
IfcRelDefinesByType (2)
5	RelatedObjects	SET [1:?] OF IfcObject	No description available.
6	RelatingType	IfcTypeObject	Reference to the type (or style) information for that object or set of objects.

Table 5.1.3.40.V

5.1.3.40.4 Concept usage

Concept	Usage	Description
IfcRoot (2)
Revision Control	General	Ownership, history, and merge state is captured using IfcOwnerHistory.
Software Identity	General	IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
Click to show 2 hidden inherited concepts

Table 5.1.3.40.W

5.1.3.40.5 Examples

Figure 5.1.3.40.B

Beam Varying Profiles
Figure 5.1.3.40.C

Bath Csg Solid
Figure 5.1.3.40.D

Mapped Shape Without Transformation
Figure 5.1.3.40.E

Mapped Shape With Transformation
Figure 5.1.3.40.F

Wall Extrusion
Figure 5.1.3.40.G

Mapped Shape With Multiple Items
Figure 5.1.3.40.H

Curve Parameters In Radians
Figure 5.1.3.40.I

Beam Varying Extrusion Paths
Figure 5.1.3.40.J

Beam Revolved Solid
Figure 5.1.3.40.K

Beam Parametric Cross Section
Figure 5.1.3.40.L

Reinforcing Stirrup
Figure 5.1.3.40.M

Basin Tessellation
Figure 5.1.3.40.N

Column Extruded Solid
Figure 5.1.3.40.O

Reinforcing Assembly
Figure 5.1.3.40.P

Linear Placement Of Signal
Figure 5.1.3.40.Q

Beam Varying Cardinal Points
Figure 5.1.3.40.R

Basin Faceted Brep
Figure 5.1.3.40.S

Curve Parameters In Degrees
Figure 5.1.3.40.T

Basin Advanced Brep

5.1.3.40.6 Formal representation

 ENTITY IfcRelDefinesByType
 SUBTYPE OF (IfcRelDefines);
	RelatedObjects : SET [1:?] OF IfcObject;
	RelatingType : IfcTypeObject;
END_ENTITY;