Occurs when the Value of a node belonging to this document is about to be changed.
Assembly: System.Xml (in System.Xml.dll)
This event allows the user to do extra checking and, if necessary, throw an exception to stop the operation. If an exception is thrown the XmlDocument returns to its original state. This event only applies to nodes that have a value.
All nodes created by this document, whether or not they have been inserted into the document, are included in this event.