IFC Architecture Layer
	Schema				New			Change description
		Entity / Function			Changed
			Attribute / WR		Deleted			affects P21 file
RESOURCE LAYER
	IfcConstraintResource
		IfcConstraintRelationship			x			Entity added	x
		IfcConstraintClassificationRelationship			x			Entity added	x
		IfcConstraint
			(INV) IsRelatedWith		x			INV added to IfcConstraintRelationship
			(INV) RelatesConstraints		x			INV added to IfcConstraintRelationship
			(INV) ClassifiedAs		x			INV added to IfcConstraintClassificationRelationship
	IfcMaterialPropertyResource
		IfcMaterialProperties
			UR1				x	Uniqueness rule removed
		IfcGeneralMaterialProperties
			UR11		x			Uniqueness rule added
		IfcWaterProperties
			UR11		x			Uniqueness rule added
		IfcFuelProperties
			UR11		x			Uniqueness rule added
		IfcProductsOfCombustionProperties
			UR11		x			Uniqueness rule added
	IfcMeasureResource
		IfcCompoundPlaneAngleMeasure
			WR1			x		Where rule changed
			WR2			x		Where rule changed
			WR3			x		Where rule changed
			WR4		x			Where rule added
		IfcDerivedUnitEnum				x		misspelling of Enumerator MOMENTOFINERTIAUNIT corrected	x
	IfcPresentationAppearanceResource
		IfcDraughtingPreDefinedCurveFont
			WR31			x		Where rule improved to include font by layer
		IfcStyledItem				x		Entity made non-abstract	x
			Name		x			Attribute promoted from subtype IfcAnnotationOccurrence	x
		IfcSurfaceStyleRendering
			Transparancy			x		Misspelling as Transparancy corrected into Transparency
		IfcSurfaceStyleWithTextures
			(INV) HasTextureCoordinates		x			INV added to IfcTextureCoordinate
	IfcPresentationDefinitionResource
		IfcAnnotationOccurrence
			Name				x	Attribute deleted and promoted to IfcStyledItem
	IfcProfileResource
		IfcCShapeProfileDef
			WR2		x			where rule added to secure correct values for profile parameter
			WR3		x			where rule added to secure correct values for profile parameter
		IfcIShapeProfileDef
			WR3		x			where rule added to secure correct values for profile parameter
	IfcQuantityResource
		IfcPhysicalQuantity
			Unit				x	Attribute deleted and demoted to IfcPhysicalSimpleQuantity
			(INV) PartOfComplex		x			INV added to IfcPhysicalComplexQuantity
		IfcPhysicalComplexQuantity			x			new entity to deal with complex quantities (such as quantity by layer)	x
		IfcPhysicalSimpleQuantity			x			new abstract entity to deal with simple quantities
	IfcRepresentationResource
		IfcRepresentationContextSameWCS				x		global rule corrected
CORE LAYER
	IfcKernel
		IfcProduct
			WR1			x		where rule improved to only enforce placement for geometric represenation
		IfcCorrectObjectAssignment				x		global function corrected, NOTDEFINED now returns TRUE
	IfcProductExtension
		IfcVirtualElement			x			new entity to enable virtual space boundaries	x
		IfcRelAssociatesMaterial
			WR1			x		where rule updated to reflect new virtual element
			WR2			x		where rule updated to allow all products to have material
		IfcRelSpaceBoundary
			WR1			x		where rule updated to reflect new virtual element
		IfcElementQuantity
			MethodOfMeasurement			x		Attribute made OPTIONAL	x
	IfcControlExtension
		IfcTimeSeriesSchedule
			ApplicableDates			x		Attribute made OPTIONAL	x
INTEROPERABILITY LAYER
	IfcSharedBldgElements
		IfcWallTypeEnum				x		Enumerator POLYGON changed into POLYGONAL	x
		IfcMember			x			new entity to enable structural member design	x
		IfcBeamAndColumnType					x	abstract entity deleted
		IfcMemberTypeEnum				x		Enumerators CHORD, PLATE, STUD added	x
	IfcSharedFacilitiesElements
		IfcServiceLifeFactor
			WR31			x		where rule updated to reflect correct inheritance structure
		IfcServiceLifeTypeEnum				x		corrected spelling of OPTIMISTICREFERENCESERVICELIFE	x
		IfcServiceLifeFactorTypeEnum				x		corrected spelling (was IfcSeviceLifeFactorTypeEnum)
DOMAIN LAYER
	IfcBuildingControlsDomain
		IfcAlarmTypeEnum				x		Enumerator BREAKGLASSBUTTON and MANUALPULLBOX added	x
		IfcSensorTypeEnum				x		Enumerator value for HEATSENSOR added	x
	IfcElectricalDomain
		IfcElectricalApplianceTypeEnum				x		ELECTRICHEATER, TUMBLEDRYER and WATERHEATER added	x
		IfcLampType			x			new entity to deal with lamps used in light fixtures	x
		IfcLampTypeEnum			x			new enumeration for types of lamps	x
		IfcElectricDistributionPoint
			WR31		x			where rule added for UserDefinedFunction
	IfcHvacDomain
		IfcTankTypeEnum				x		Enumerator values EXPANSION and PRESSUREVESSEL added	x
	IfcStructuralAnalysisDomain
		IfcRelAssociatesProfileProperties				x		made it a subtype of IfcRelAssociates	x
		IfcStructuralAction
			DestablizingLoad			x		Misspelling as DestablizingLoad corrected into DestabilizingLoad