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);


## 8.11.3.3.4 Formal representation

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