public event OnCollectionAddEvent OnCollectionAdd;
 PropertyDescription 
   Event Name OnCollectionAdd  
    Delgate

public delegate void OnCollectionAddEvent(object source, XmlCollectionAddEventArgs args);

public class XmlCollectionAddEventArgs : EventArgs
{
    private object _item = null;
    public XmlCollectionAddEventArgs(object item) { _item = item; }
    public object item { get { return _item; } } // the item being added
}

 
  Description Fired before an item is added to the collection.  
  Remarks