It is possible to pass data from CLI managed code to unmanaged code. This always involves a transition from managed to unmanaged code, which has some runtime cost, but data can often be transferred without copying. When data must be reformatted the VES provides a reasonable specification of default behavior, but it is possible to use metadata to explicitly require other forms of marshalling (i.e., reformatted copying). The metadata also allows access to unmanaged methods through implementation-specific pre-existing mechanisms.