IFC 4.3.0.1 (IFC4X3) development

8.11.3.3 IfcConversionBasedUnitWithOffset

8.11.3.3.1 Semantic definition

IfcConversionBasedUnitWithOffset is a unit which is converted from another unit by applying a conversion factor and an offset.

Example: The temperature unit Fahrenheit is based on the temperature unit Kelvin as follows:

$$ f = 1.8k - 459.67 $$

wherein k is an absolute temperature expressed in Kelvin and f is the same temperature in Fahrenheit. The following entity instances provide Fahrenheit as a unit:

IfcConversionBasedUnitWithOffset(
     IfcDimensionalExponents(0, 0, 0, 0, 1, 0, 0),
     THERMODYNAMICTEMPERATUREUNIT,
     'Fahrenheit',
     IfcMeasureWithUnit(
         IfcThermodynamicTemperatureMeasure(1/1.8),
         IfcSIUnit(THERMODYNAMICTEMPERATUREUNIT, ?, KELVIN)),
     -459.67);

8.11.3.3.2 Entity inheritance

8.11.3.3.3 Attributes

# Attribute Type Description
IfcNamedUnit (2)
1 Dimensions IfcDimensionalExponents

The dimensional exponents of the SI base units by which the named unit is defined.

2 UnitType IfcUnitEnum

The type of the unit.

IfcConversionBasedUnit (3)
3 Name IfcLabel

The word, or group of words, by which the conversion based unit is referred to.

4 ConversionFactor IfcMeasureWithUnit

The physical quantity from which the converted unit is derived.

HasExternalReference SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects

Reference to external information, e.g. library, classification, or document information, which is associated with the conversion-based unit.

Click to show 5 hidden inherited attributes Click to hide 5 inherited attributes
IfcConversionBasedUnitWithOffset (1)
5 ConversionOffset IfcReal

A positive or negative offset to add after the inherited ConversionFactor was applied.

Table 8.11.3.3.A

8.11.3.3.4 Formal representation

ENTITY IfcConversionBasedUnitWithOffset
 SUBTYPE OF (IfcConversionBasedUnit);
	ConversionOffset : IfcReal;
END_ENTITY;

8.11.3.3.5 References

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8.11.3.3.6 Changelog

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