A mappable object is not a separate type, but is an instance of an Object type that implements the method Object::ApplyUVWMap() and returns true from the Object::IsMappable() method.
A mappable object may be requested by certain modifiers (e.g. Mapping Coordinate Modifiers). When Mappable objects are requested they are identified by the Class_ID``mapObjectClassID.
Objects that are mappable (or know how to convert themselves to a mappable object) will return TRUE in the method Object::CanConvertToType() when passed the Class_ID``mapObjectClassID.
PatchObject, PolyObject, and TriObject are examples of mappable objects.
Requests by the geometry pipeline for mappable objects are done using the Class_ID``mapObjectClassID. Objects that are mappable should return TRUE in the method Object::CanConvertToType() when passed mapObjectClassID, and should return the this pointer from the implementation of the method Object::ConvertToType() when passed mapObjectClassID.