IfcRamp
Definition from ISO 67071:1989: Inclined way or floor joining two surfaces at different levels.
Definition of IAI: An vertical passageway which provides a human circulation link between one floor level and another floor level at a different elevation. It may include a landing as an intermediate floor slab. A ramp normally does not include steps (stepped ramps are out of scope for this IFC Release).
The ramp is a container entity that aggregates all components of the ramp, it represents. The aggregation is handled via the IfcRelAggregates relationship, relating an IfcRamp with the related flights (IfcRampFlight) and landings (IfcSlab with type 'Landing').
HISTORY New Entity in IFC Release 2.0.
Property Set Use Definition:
The property sets relating to the IfcRamp are defined by the IfcPropertySet and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following property set definitions specific to the IfcRamp are part of this IFC release:
Geometry Use Definitions:
The geometric representation of IfcRamp is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Independent geometric representations should only be used when the IfcRamp is not defined as an aggregate. If defined as an aggregate, the geometric representation is the sum of the representation of the components within the aggregate.
Local placement
The local placement for IfcRamp is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.
If the LocalPlacement is given for the IfcRamp, then all components, which are aggregated to the ramp should use this placement as their relative placement.
Geometric Representations
If the IfcRamp has components (referenced by SELF\IfcProduct.IsDecomposedBy) then no independent geometric representation shall be defined for the IfcRamp. The IfcRamp is then geometrically represented by the geometric representation of its components. The components are accessed via SELF\IfcProduct.IsDecomposedBy[1].RelatedObjects.
If the IfcRamp has no components defined (empty set of SELF\IfcProduct.IsDecomposedBy) then the IfcRamp may be represented by an IfcShapeRepresentation with the RepresentationType = 'Brep'.
Illustration:
IfcRamp defining only the local placement for all components. 
EXPRESS specification:

ShapeType  :  Predefined shape types for a ramp that are specified in an Enum. 
WR1  :  Either the ramp is not decomposed into its flights and landings (the ramp can have independent geometry),
or the geometry shall not be given at IfcRamp directly. 
