+ // Save a pointer to a data holder intended to pass data Driver -> Operation.
+ // This method should be called by Operation to set the data holder.
+ // An instance of GEOM_Function that sets the data holder will remove the
+ // corresponding OCAF attribute at it's destruction
+ Standard_EXPORT void SetCallBackData( void* data );
+
+ // Returns a pointer to a data holder intended to pass data Driver -> Operation.
+ // This method should be called by Driver to get the data holder to fill it in.
+ // Returns NULL if the Operation have not set the data holder.
+ Standard_EXPORT void* GetCallBackData();
+