IFC 4.3.x development

8.3.3.2 IfcMetric

Change log

IFC4

additions attributes ReferencePath
modificationsattributes DataValue is_optionalChanged from False to True

8.3.3.2.1 Semantic definitions at the entity

An IfcMetric is used to capture quantitative resultant metrics that can be applied to objectives.

IfcMetric is a subtype of IfcConstraint and may be associated with any subtype of IfcRoot through the IfcRelAssociatesConstraint relationship in the IfcControlExtension schema, or may be associated with IfcProperty by IfcResourceConstraintRelationship.

The aim of IfcMetric is to capture the quantitative aspects of a constraint.

HISTORY  New entity in IFC2.0.

IFC4 CHANGE  ReferencePath attribute added for indicating the value to be constrained along a path of attribute references.

8.3.3.2.1 Attributes

# Attribute Type Description
IfcConstraint
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 RelatedResourceObjectsReference to an external references, e.g. library, classification, or document information, that are associated to the constraint.

> IFC4 CHANGE New inverse attribute.
PropertiesForConstraintSET [0:?] OF IfcResourceConstraintRelationship FOR RelatingConstraint Reference to the properties to which the constraint is applied.
IfcMetric
8 Benchmark IfcBenchmarkEnum Enumeration that identifies the type of benchmark data.
9 ValueSource OPTIONAL IfcLabel Reference source for data values.

If DataValue refers to an IfcTable, this attribute identifies the relevent column identified by IfcTableColumn.Identifier.
10 DataValue OPTIONAL IfcMetricValueSelect The value to be compared on associated objects. A null value indicates comparison to null.

> IFC4 ADD1 CHANGE  This attribute is now optional.
11 ReferencePath OPTIONAL IfcReference Optional path to an attribute to be constrained on associated objects.

If provided, the metric may be validated by resolving the path to the current value on associated object(s), and comparing such value with DataValue according to the Benchmark.

8.3.3.2.2 Entity inheritance

dot_inheritance IfcMetric IfcMetric IfcConstraint IfcConstraint IfcMetric->IfcConstraint IfcObjective IfcObjective IfcObjective->IfcConstraint

8.3.3.2.3 Formal representations

ENTITY IfcMetric
 SUBTYPE OF (IfcConstraint);
	Benchmark : IfcBenchmarkEnum;
	ValueSource : OPTIONAL IfcLabel;
	DataValue : OPTIONAL IfcMetricValueSelect;
	ReferencePath : OPTIONAL IfcReference;
END_ENTITY;