IfcPropertyConstraintRelationship

Definition from IAI: An IfcPropertyConstraintRelationship is a relationship class that enables a constraint to be related to one or more properties.

> HISTORY: New entity in Release IFC2x Edition 2.

### Use Definition

An IfcPropertyConstraintRelationship allows for the specification of a constraint to be applied to many properties. The constraints applied therefore enable a property to carry values identifying requirements as well as those identifying the fulfilment of those requirements.

The example below shows how a constraint may be applied to a property within a property set. For simplicity, only the mandatory attributes are shown as asserted. It shows how a property 'ThingWeight' which has a nominal value of 19.5 kg has two constraints that are logically aggregated by an AND connection. One of the constraints has a benchmark of 'GREATERTHANOREQUALTO' whilst the second has a benchmark of 'LESSTHANOREQUALTO'. This means that the constraint must lie between these two bounding values. The relating constraint is instantiated as an objective named as 'Weight Constraint' and qualified as a SPECIFICATION constraint. The two related constraints are both specified as metrics since they can have specific values.

EXPRESS specification:

ENTITY IfcPropertyConstraintRelationship;
RelatingConstraint | : | IfcConstraint;
RelatedProperties | : | SET [1:?] OF IfcProperty;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;
END_ENTITY;

Attribute definitions:

RelatingConstraint | : | The constraint that is to be related.
RelatedProperties | : | The properties to which a constraint is to be related.
Name | : | A name used to identify or qualify the property constraint relationship.
Description | : | A description that may apply additional information about a property constraint relationship.

Inheritance graph

ENTITY IfcPropertyConstraintRelationship;
ENTITY IfcPropertyConstraintRelationship;
RelatingConstraint | : | IfcConstraint;
RelatedProperties | : | SET [1:?] OF IfcProperty;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;
END_ENTITY;