private void OnListChanged( object sender, XmlNodeChangedEventArgs args ) {
XmlElementList elemList = (XmlElementList)this.elemList.Target;
if (null != elemList) {
elemList.ConcurrencyCheck(args);
} else {
this.doc.NodeInserted -= this.nodeChangeHandler;
this.doc.NodeRemoved -= this.nodeChangeHandler;
}
}