int      oyStructSignalForward_      ( oyObserver_s      * observer,
                                       oySIGNAL_e          signal_type,
                                       oyStruct_s        * signal_data );
oyObserver_s * oyObserver_Copy_      ( oyObserver_s      * obj,
                                       oyObject_s          object );
oyStructList_s * oyStruct_ObserverListGet_(
                                       oyStruct_s        * obj,
                                       const char        * reg );
int        oyStruct_ObserverRemove_  ( oyStructList_s    * list,
                                       oyStruct_s        * obj,
                                       int                 observer,
                                       oyObserver_Signal_f signalFunc );
