Definition from buildingSMART: The physical quantity,
IfcPhysicalSimpleQuantity, is an entity that holds a single quantity
measure value (as defined at the subtypes of IfcPhysicalSimpleQuantity)
together with a semantic definition of the usage for the measure value.
EXAMPLE: An element, like a wall, may have
several area measures, like footprint area, left wall face area, right wall
face area. These areas would be given by three instances of the area quantity
subtype, with different Name string values.
A section "Quantity Use Definition" at individual entities as subtypes
of IfcBuildingElement gives guidance to the usage of the Name
attribute to characterize the individual quantities. If the Unit
attribute is given, the value attribute (introduced at the level of subtypes of
IfcPhysicalSimpleQuantity) are given as quantities of this unit,
otherwise the global unit definitions (given by IfcUnitAssignment) are
HISTORY New entity in IFC Release 2x2
IFC2x2 ADDENDUM 1 CHANGE The abstract
entity IfcPhysicalSimpleQuantity has been added. Upward compatibility
for file based exchange is guaranteed.
|| 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.