8.7.2.4 IfcQuantityLength

Quantité de longueur
Mengenangabe - Länge

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.

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 IFC2x. It replaces the calcXxx attributes used in previous IFC Releases.

XSD Specification:

 <xs:element name="IfcQuantityLength" type="ifc:IfcQuantityLength" substitutionGroup="ifc:IfcPhysicalSimpleQuantity" nillable="true"/>
 <xs:complexType name="IfcQuantityLength">
  <xs:complexContent>
   <xs:extension base="ifc:IfcPhysicalSimpleQuantity">
    <xs:attribute name="LengthValue" type="ifc:IfcLengthMeasure" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>

EXPRESS Specification:

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

Attribute Definitions:

LengthValue : Length measure value of this quantity.
Formula : 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.
IFC4 CHANGE Attribute added to the end of the attribute list.

Formal Propositions:

WR21 : If a unit is given, the unit type shall be a length unit.
WR22 : A valid length quantity shall be greater than or equal to zero.

Inheritance Graph:

ENTITY IfcQuantityLength
ENTITY IfcPhysicalQuantity
Name : IfcLabel;
Description : OPTIONAL IfcStrippedOptional;
INVERSE
ENTITY IfcPhysicalSimpleQuantity
Unit : OPTIONAL IfcStrippedOptional;
ENTITY IfcQuantityLength
LengthValue : IfcLengthMeasure;
Formula : OPTIONAL IfcStrippedOptional;
END_ENTITY;

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