typedef void (* XPLMObjectLoaded_f)(
                         XPLMObjectRef        inObject,    
                         void *               inRefcon);    

You provide this callback when loading an object asynchronously; it will be called once the object is loaded. Your refcon is passed back. The object ref passed in is the newly loaded object (ready for use) or NULL if an error occured.

If your plugin is disabled, this callback will be delivered as soon as the plugin is re-enabled. If your plugin is unloaded before this callback is ever called, the SDK will release the object handle for you.