|InfoPath Developer Reference|
Version Added: InfoPath 2003
expression An expression that returns a DataDOMEvent object.
The NewValue property contains the value of the XML DOM node that will replace the existing value. To get the original value of the XML DOM node, use the OldValue property of the DataDOMEvent object.
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In the following example, the NewValue property of the DataDOMEvent object is used to determine whether the new value of the XML DOM node is an empty string. If it is not, the code sets other fields to be empty strings.