What is the standard prefix for the opposite of an event handler?

Question

I have an object with a method that should be called by user code when long pressing on a map. The same object also has event handlers that it uses to tell its users that an event occurred.

I have prefixed the names of the event handlers with on, e.g. onDrawingComplete, as is a common naming convention for event handlers.

But I'm not sure what the standard naming convention is for the opposite case - methods that should be called by user code to tell an object that an external event occurred. For now, I have used the prefix handle, e.g. handleMapLongPress.

Here's some pseudo code to illustrate:

MyClass{
   Function onDrawingComplete; 
   void handleMapLongPress(LatLng coordinates);
}

myInstance = new MyClass();
myInstance.onDrawingComplete = (){
  // Do something in response to a drawing being completed
}

myMap = new Map();
myMap.onLongPress = (coordinates){
  // Tell myInstance that there was a longpress at [coordinates]
  myInstance.handleMapLongPress(coordinates);
}

Is there a standard naming convention for the kind of method that should be called by user code to let an object know about an event that occurred somewhere outside it?