IFC 4.3.0.1 (IFC4X3) development

8.17.3.6 IfcQuantityLength

8.17.3.6.1 Semantic definition

IfcQuantityLength is a physical quantity that defines a derived length measure to provide an element's physical property. It is normally derived from the physical properties of the element under the specific measure rules given by a method of measurement.

8.17.3.6.2 Entity inheritance

8.17.3.6.3 Attributes

# Attribute Type Description
IfcPhysicalQuantity (4)
1 Name IfcLabel

Name of the element quantity or measure. The name attribute has to be made recognizable by further agreements.

2 Description OPTIONAL IfcText

Further explanation that might be given to the quantity.

HasExternalReferences SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects

Reference to an external reference, e.g. library, classification, or document information, that is associated to the quantity.

PartOfComplex SET [0:1] OF IfcPhysicalComplexQuantity FOR HasQuantities

Reference to a physical complex quantity in which the physical quantity may be contained.

IfcPhysicalSimpleQuantity (1)
3 Unit OPTIONAL IfcNamedUnit

Optional assignment of a unit. If no unit is given, then the global unit assignment, as established at the IfcProject, applies to the quantity measures.

Click to show 5 hidden inherited attributes Click to hide 5 inherited attributes
IfcQuantityLength (2)
4 LengthValue IfcLengthMeasure

Length measure value of this quantity.

5 Formula OPTIONAL IfcLabel

A formula by which the quantity has been calculated. It can be assigned in addition to the actual value of the quantity. Formulas could be mathematic calculations (like width x height), database links, or a combination. The formula is for informational purposes only.

Table 8.17.3.6.A

8.17.3.6.4 Formal propositions

Name Description
WR21

If a unit is given, the unit type shall be a length unit.

NOT(EXISTS(SELF\IfcPhysicalSimpleQuantity.Unit)) OR
   (SELF\IfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.LENGTHUNIT)
WR22

A valid length quantity shall be greater than or equal to zero.

LengthValue >= 0.
Table 8.17.3.6.B

8.17.3.6.5 Formal representation

ENTITY IfcQuantityLength
 SUBTYPE OF (IfcPhysicalSimpleQuantity);
	LengthValue : IfcLengthMeasure;
	Formula : OPTIONAL IfcLabel;
 WHERE
	WR21 : NOT(EXISTS(SELF\IfcPhysicalSimpleQuantity.Unit)) OR
   (SELF\IfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.LENGTHUNIT);
	WR22 : LengthValue >= 0.;
END_ENTITY;

8.17.3.6.6 References

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8.17.3.6.7 Changelog

  • attribute, Formula