  oyFilterPlug_s_   ** plugs;          /**< possible input connectors */
  int                  plugs_n_;       /**< readonly number of inputs */
  oyFilterSocket_s_ ** sockets;        /**< possible output connectors */
  int                  sockets_n_;     /**< readonly number of outputs */

  oyFilterCore_s_    * core;           /**< the filter core */
  char               * relatives_;     /**< @private hint about belonging to a filter */
  oyOptions_s        * tags;           /**< infos, e.g. group markers */

  /** the filters private data, requested over 
   *  oyCMMapi4_s::oyCMMFilterNode_ContextToMem() and converted to
   *  oyCMMapi4_s::context_type */
  oyPointer_s        * backend_data;
  /** the processing function and node connector descriptions */
  oyCMMapi7_s_       * api7_;
