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IfcQuantityLength

Definition from IAI: A physical quantity, IfcQuantityLength, 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.

EXAMPLE: A rafter within a roof construction may be measured according to its length (taking a common cross section into account). The actual size of the length depends on the method of measurement used.

HISTORY New entity in IFC Release 2.x
NOTE: It replaces the calcXxx attributes used in previous IFC Releases
ISSUE See issues for changes made in IFC Release 2.x

EXPRESS specification:

ENTITY IfcQuantityLength
SUBTYPE OF ( IfcPhysicalQuantity);
LengthValue  :  IfcLengthMeasure;
WHERE
WR1  :  NOT(EXISTS(SELF\IfcPhysicalQuantity.Unit)) OR (SELF\IfcPhysicalQuantity.Unit.UnitType = IfcUnitEnum.LENGTHUNIT);
END_ENTITY;

Attribute definitions:

LengthValue  :  Length measure value of this quantity.

Formal Propositions:

WR1  :  If a unit is given, the unit type shall be lenght unit.

References (1):

Name Type Referred through Express-G
IfcPhysicalQuantity Entity
Subtype
Diagram 1

Inheritance graph

ENTITY IfcQuantityLength;
ENTITY IfcPhysicalQuantity;
Name  :  IfcLabel;
Description  :  OPTIONAL IfcText;
Unit  :  OPTIONAL IfcNamedUnit;
ENTITY IfcQuantityLength;
LengthValue  :  IfcLengthMeasure;
END_ENTITY;