IFC 4.3.0.1 (IFC4X3_TC1)

8.3.3.1 IfcConstraint

ABSTRACT This definition may not be instantiated

8.3.3.1.1 Semantic definition

An IfcConstraint is used to define a constraint or limiting value or boundary condition that may be applied to an object or to the value of a property.

Constraints may be subdivided into user-defined constraints and system-defined constraints. User-defined constraints are applied by a user and are restricted to high-level definitions such as object properties. System-defined constraints may apply to any object attribute, are typically defined by an application to enforce data validation or parametric behavior, and are intended to be enforced by applications but not to be directly editable by an end-user.

IfcConstraint may be associated with any subtype of IfcObjectDefinition or IfcPropertyDefinition through the IfcRelAssociatesConstraint relationship to indicate a system-defined constraint, or may be associated with IfcResourceObjectSelect (such as IfcPropertySingleValue) by IfcResourceConstraintRelationship to indicate a user-defined constraint.

A constraint must have a name applied through the IfcConstraint.Name attribute and optionally, a description through IfcConstraint.Description. The grade of the constraint (hard, soft, advisory) must be specified through IfcConstraint.ConstraintGrade or IfcConstraint.UserDefinedGrade whilst the source, creating actor and time at which the constraint is created may be optionally asserted through IfcConstraint.ConstraintSource, IfcConstraint.CreatingActor and IfcConstraint.CreationTime.

A constraint may also have additional external information (such as classification or document information) associated to it by IfcExternalReferenceRelationship, accessible through inverse attribute IfcConstraint.HasExternalReferences

8.3.3.1.2 Entity inheritance

8.3.3.1.3 Attributes

# Attribute Type Description
IfcConstraint (9)
1 Name IfcLabel

A human-readable name to be used for the constraint.

2 Description OPTIONAL IfcText

A human-readable description that may apply additional information about a constraint.

3 ConstraintGrade IfcConstraintEnum

Enumeration that qualifies the type of constraint.

4 ConstraintSource OPTIONAL IfcLabel

Any source material, such as a code or standard, from which the constraint originated.

5 CreatingActor OPTIONAL IfcActorSelect

Person and/or organization that has created the constraint.

6 CreationTime OPTIONAL IfcDateTime

Time when information specifying the constraint instance was created.

7 UserDefinedGrade OPTIONAL IfcLabel

Allows for specification of user defined grade of the constraint beyond the enumeration values (hard, soft, advisory) provided by ConstraintGrade attribute of type IfcConstraintEnum. When a value is provided for attribute UserDefinedGrade in parallel the attribute ConstraintGrade shall have enumeration value USERDEFINED.

HasExternalReferences SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects

Reference to an external references, e.g. library, classification, or document information, that are associated to the constraint.

PropertiesForConstraint SET [0:?] OF IfcResourceConstraintRelationship FOR RelatingConstraint

Reference to the properties to which the constraint is applied.

Table 8.3.3.1.A

8.3.3.1.4 Formal propositions

Name Description
WR11

The attribute UserDefinedGrade must be asserted when the value of the IfcConstraintGradeEnum is set to USERDEFINED.

(ConstraintGrade <> IfcConstraintEnum.USERDEFINED) OR
((ConstraintGrade = IfcConstraintEnum.USERDEFINED) AND EXISTS(SELF\IfcConstraint.UserDefinedGrade))
Table 8.3.3.1.B

8.3.3.1.5 Formal representation

ENTITY IfcConstraint
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcMetric
	,IfcObjective));
	Name : IfcLabel;
	Description : OPTIONAL IfcText;
	ConstraintGrade : IfcConstraintEnum;
	ConstraintSource : OPTIONAL IfcLabel;
	CreatingActor : OPTIONAL IfcActorSelect;
	CreationTime : OPTIONAL IfcDateTime;
	UserDefinedGrade : OPTIONAL IfcLabel;
 INVERSE
	HasExternalReferences : SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects;
	PropertiesForConstraint : SET [0:?] OF IfcResourceConstraintRelationship FOR RelatingConstraint;
 WHERE
	WR11 : (ConstraintGrade <> IfcConstraintEnum.USERDEFINED) OR
((ConstraintGrade = IfcConstraintEnum.USERDEFINED) AND EXISTS(SELF\IfcConstraint.UserDefinedGrade));
END_ENTITY;

8.3.3.1.6 References

8.3.3.1.7 Changelog

8.3.3.1.7.1 IFC4

  • inverse attribute, Aggregates
  • inverse attribute, IsAggregatedIn
  • inverse attribute, IsRelatedWith
  • inverse attribute, PropertiesForConstraint
  • attribute CreationTime type, Changed from "IfcDateTimeSelect" to "IfcDateTime"
  • inverse attribute ClassifiedAs name, Changed from "ClassifiedAs" to "HasExternalReferences"
  • inverse attribute ClassifiedAs type, Changed from "SET OF [0:?] IfcConstraintClassificationRelationship FOR ClassifiedConstraint" to "SET OF [0:?] IfcExternalReferenceRelationship FOR RelatedResourceObjects"
  • inverse attribute RelatesConstraints name, Changed from "RelatesConstraints" to "PropertiesForConstraint"
  • inverse attribute RelatesConstraints type, Changed from "SET OF [0:?] IfcConstraintRelationship FOR RelatingConstraint" to "SET OF [0:?] IfcResourceConstraintRelationship FOR RelatingConstraint"