IFC 4.3.x development

5.1.3.37 IfcRelDefines

Change log

IFC4

deletionsattributesRelatedObjects

5.1.3.37.1 Semantic definitions at the entity

A generic and abstract relationship which subtypes are used to:

  • assign a object type to an object occurrence
  • assign a property set to an object instance
  • assign a property set template to a property set

EXAMPLE  Several instances of windows within the IFC project model may be of the same (catalogue or manufacturer) type. Thereby they share the same properties. This relationship is established by the subtype IfcRelDefinesByType of IfcRelDefines relationship assigning an IfcWindowStyle to multiple occurrences IfcWindow.

EXAMPLE  The (same) property set, e.g.  Pset_ProductManufacturerInfo, keeping the manufacturer name, label and production year of a product, can be assigned to one, or many instances of furnishing. This relationship is established by the subtype IfcRelDefinesByProperties of IfcRelDefines relationship assigning an IfcPropertySet to one or more instances of IfcFurnishingElement.

HISTORY  New entity in IFC2x.

IFC4 CHANGE  The attribute RelatedObjects had been demoted to the subtypes IfcRelDefinesByProperties and IfcRelDefinesByType.

#Attribute Type Description
IfcRoot
1GlobalId IfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world.
2OwnerHistoryOPTIONAL IfcOwnerHistoryAssignment 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 in stored - either as addition, deletion or modification.

> IFC4 CHANGE  The attribute has been changed to be OPTIONAL.
3Name 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.
4Description OPTIONAL IfcText Optional description, provided for exchanging informative comments.

5.1.3.37.1 Entity inheritance

dot_inheritance IfcRelDefines_children 3 more... IfcRelDefines IfcRelDefines IfcRelDefines_children->IfcRelDefines IfcRelationship IfcRelationship IfcRelDefines->IfcRelationship IfcRelationship_children 5 more... IfcRelationship_children->IfcRelationship IfcRoot IfcRoot IfcRelationship->IfcRoot IfcObjectDefinition IfcObjectDefinition IfcObjectDefinition->IfcRoot IfcPropertyDefinition IfcPropertyDefinition IfcPropertyDefinition->IfcRoot

5.1.3.37.2 Definitions applying to General Usage

5.1.3.37.2.1 Identity

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

5.1.3.37.2.2 Revision Control

Ownership, history, and merge state is captured using IfcOwnerHistory.

5.1.3.37.3 Formal representations

ENTITY IfcRelDefines
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcRelDefinesByObject
	,IfcRelDefinesByProperties
	,IfcRelDefinesByTemplate
	,IfcRelDefinesByType))
 SUBTYPE OF (IfcRelationship);
END_ENTITY;