8.16.3.7 IfcPropertyDependencyRelationship

Merkmal - Abhängigkeitsrelation

An IfcPropertyDependencyRelationship describes an identified dependency between the value of one property and that of another.

HISTORY  New entity in IFC2x2
IFC4 CHANGE  Made subtype of IfcResourceLevelRelationship (attribute order changed).

Use Definition

Whilst the IfcPropertyDependencyRelationship may be used to describe the dependency, and it may do so in terms of the expression of how the dependency operates, it is not possible through the current IFC model for the value of the related property to be actually derived from the value of the relating property. The determination of value according to the dependency is required to be performed by an application that can then use the Expression attribute to flag the form of the dependency.


XSD Specification:

 <xs:element name="IfcPropertyDependencyRelationship" type="ifc:IfcPropertyDependencyRelationship" substitutionGroup="ifc:IfcResourceLevelRelationship" nillable="true"/>
 <xs:complexType name="IfcPropertyDependencyRelationship">
  <xs:complexContent>
   <xs:extension base="ifc:IfcResourceLevelRelationship">
    <xs:sequence>
     <xs:element name="DependingProperty" type="ifc:IfcProperty" nillable="true"/>
     <xs:element name="DependantProperty" type="ifc:IfcProperty" nillable="true"/>
    </xs:sequence>
    <xs:attribute name="Expression" type="ifc:IfcText" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>

EXPRESS Specification:

ENTITY IfcPropertyDependencyRelationship
SUBTYPE OF IfcResourceLevelRelationship;
DependingProperty : IfcProperty;
DependantProperty : IfcProperty;
Expression : OPTIONAL IfcText;
WHERE
NoSelfReference : DependingProperty :<>: DependantProperty;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

DependingProperty : The property on which the relationship depends.
DependantProperty : The dependant property.
Expression : Expression that further describes the nature of the dependency relation.

Formal Propositions:

NoSelfReference : The DependingProperty shall not point to the same instance as the DependantProperty.

Inheritance Graph:

ENTITY IfcPropertyDependencyRelationship
ENTITY IfcResourceLevelRelationship
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcPropertyDependencyRelationship
DependingProperty : IfcProperty;
DependantProperty : IfcProperty;
Expression : OPTIONAL IfcText;
END_ENTITY;

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