These are all non-abstract subtypes of IfcRepresentationItem. Most of them implemented, details follow.

IFC2X3

• IfcAxis1Placement
• IfcAxis2Placement2D
• IfcAxis2Placement3D
• IfcBlock
• IfcBooleanClippingResult
• IfcBooleanResult
• IfcCartesianPoint
• IfcCartesianTransformationOperator2D
• IfcCartesianTransformationOperator2DnonUniform
• IfcCartesianTransformationOperator3D
• IfcCartesianTransformationOperator3DnonUniform
• IfcCircle
• IfcClosedShell
• IfcCompositeCurve
• IfcCompositeCurveSegment
• IfcConnectedFaceSet
• IfcCsgSolid
• IfcCurveBoundedPlane
• IfcDirection
• IfcEdge
• IfcEdgeCurve
• IfcEdgeLoop
• IfcEllipse
• IfcExtrudedAreaSolid
• IfcFace
• IfcFaceBasedSurfaceModel
• IfcFaceBound
• IfcFaceOuterBound
• IfcFaceSurface
• IfcFacetedBrep
• IfcFacetedBrepWithVoids
• IfcGeometricSet
• IfcHalfSpaceSolid
• IfcLine
• IfcMappedItem
• IfcOffsetCurve2D
• IfcOffsetCurve3D
• IfcOpenShell
• IfcOrientedEdge
• IfcPath
• IfcPlane
• IfcPointOnCurve
• IfcPointOnSurface
• IfcPolyLoop
• IfcPolygonalBoundedHalfSpace
• IfcPolyline
• IfcRectangularPyramid
• IfcRectangularTrimmedSurface
• IfcRevolvedAreaSolid
• IfcRightCircularCone
• IfcRightCircularCylinder
• IfcSectionedSpine
• IfcShellBasedSurfaceModel
• IfcSphere
• IfcStyledItem
• IfcSubedge
• IfcSurfaceCurveSweptAreaSolid
• IfcSurfaceOfLinearExtrusion
• IfcSurfaceOfRevolution
• IfcSweptDiskSolid
• IfcTrimmedCurve
• IfcVector
• IfcVertexLoop
• IfcVertexPoint

No support planned:

• Ifc2DCompositeCurve (DEPRICATED, removed from IFC4, supertype supported)
• IfcBezierCurve (DEPRICATED, removed from IFC4)
• IfcBoundedSurface (No attributes, made abstract in IFC4)
• IfcBoundingBox
• IfcBoxedHalfSpace (supertype supported, no meaningful behaviour added)
• IfcGeometricCurveSet (supertype supported, no meaningful behaviour added)
• IfcLoop (No attributes, should be abstract?)
• IfcVertex (No attributes, should be abstract?)
• IfcRationalBezierCurve
• IfcAnnotationFillArea
• IfcAnnotationSurface
• IfcDefinedSymbol
• IfcFillAreaStyleHatching
• IfcFillAreaStyleTileSymbolWithStyle
• IfcFillAreaStyleTiles
• IfcOneDirectionRepeatFactor
• IfcPlanarBox
• IfcPlanarExtent
• IfcTextLiteral
• IfcTextLiteralWithExtent
• IfcTwoDirectionRepeatFactor
• IfcAnnotationCurveOccurrence
• IfcAnnotationFillAreaOccurrence
• IfcAnnotationSurfaceOccurrence
• IfcAnnotationSymbolOccurrence
• IfcAnnotationTextOccurrence
• IfcDimensionCurve
• IfcDimensionCurveTerminator
• IfcProjectionCurve
• IfcTerminatorSymbol
• IfcAngularDimension
• IfcDiameterDimension
• IfcDimensionCurveDirectedCallout
• IfcDraughtingCallout
• IfcLinearDimension
• IfcRadiusDimension
• IfcStructuredDimensionCallout
• IfcLightSourceAmbient
• IfcLightSourceDirectional
• IfcLightSourceGoniometric
• IfcLightSourcePositional
• IfcLightSourceSpot

IFC4

• IfcAdvancedBrep
• IfcAdvancedBrepWithVoids
• IfcAdvancedFace
• IfcAxis1Placement
• IfcAxis2Placement2D
• IfcAxis2Placement3D
• IfcBSplineCurveWithKnots
• IfcBSplineSurfaceWithKnots
• IfcBlock
• IfcBooleanClippingResult
• IfcBooleanResult
• IfcBoundaryCurve
• IfcBoundingBox
• IfcBoxedHalfSpace
• IfcCartesianPoint
• IfcCartesianPointList2D
• IfcCartesianPointList3D
• IfcCartesianTransformationOperator2D
• IfcCartesianTransformationOperator2DnonUniform
• IfcCartesianTransformationOperator3D
• IfcCartesianTransformationOperator3DnonUniform
• IfcCircle
• IfcClosedShell
• IfcCompositeCurve
• IfcCompositeCurveOnSurface
• IfcCompositeCurveSegment
• IfcConnectedFaceSet
• IfcCsgSolid
• IfcCurveBoundedPlane
• IfcCurveBoundedSurface
• IfcCylindricalSurface
• IfcDirection
• IfcEdge
• IfcEdgeCurve
• IfcEdgeLoop
• IfcEllipse
• IfcExtrudedAreaSolid
• IfcExtrudedAreaSolidTapered
• IfcFace
• IfcFaceBasedSurfaceModel
• IfcFaceBound
• IfcFaceOuterBound
• IfcFaceSurface
• IfcFacetedBrep
• IfcFacetedBrepWithVoids
• IfcFixedReferenceSweptAreaSolid
• IfcGeometricCurveSet
• IfcGeometricSet
• IfcHalfSpaceSolid
• IfcIndexedPolyCurve
• IfcLine
• IfcLoop
• IfcMappedItem
• IfcOffsetCurve2D
• IfcOffsetCurve3D
• IfcOpenShell
• IfcOrientedEdge
• IfcOuterBoundaryCurve
• IfcPath
• IfcPcurve
• IfcPlane
• IfcPointOnCurve
• IfcPointOnSurface
• IfcPolyLoop
• IfcPolygonalBoundedHalfSpace
• IfcPolyline
• IfcRationalBSplineCurveWithKnots
• IfcRationalBSplineSurfaceWithKnots
• IfcRectangularPyramid
• IfcRectangularTrimmedSurface
• IfcReparametrisedCompositeCurveSegment
• IfcRevolvedAreaSolid
• IfcRevolvedAreaSolidTapered
• IfcRightCircularCone
• IfcRightCircularCylinder
• IfcSectionedSpine
• IfcShellBasedSurfaceModel
• IfcSphere
• IfcStyledItem
• IfcSubedge
• IfcSurfaceCurveSweptAreaSolid
• IfcSurfaceOfLinearExtrusion
• IfcSurfaceOfRevolution
• IfcSweptDiskSolid
• IfcSweptDiskSolidPolygonal
• IfcTriangulatedFaceSet
• IfcTrimmedCurve
• IfcVector
• IfcVertex
• IfcVertexLoop
• IfcVertexPoint

No support planned:

• IfcAnnotationFillArea
• IfcFillAreaStyleHatching
• IfcFillAreaStyleTiles
• IfcPlanarBox
• IfcPlanarExtent
• IfcTextLiteral
• IfcTextLiteralWithExtent
• IfcLightSourceAmbient
• IfcLightSourceDirectional
• IfcLightSourceGoniometric
• IfcLightSourcePositional
• IfcLightSourceSpot