|InfoPath Developer Reference|
Version Added: InfoPath 2003
expression An expression that returns a Window object.
The XDocument property can be used only with the editing window types; if used with a designing window type, it will return an error. It will also return an error if no form is open in the form area.
Security Level 2: Can be accessed only by forms running in the same domain as the currently open form, or by forms that have been granted cross-domain permissions.
In the following example, the XDocument property of the Window object is used to set a reference to the form's underlying XML document that is associated with the currently active window: