What is the difference between well formedness and validation?
XMLSpy® 2010 offers you a check for well formedness as well as a validity check against a Schema or DTD. The validity check can be turned off in Tools/Options/File types tab by selecting a file extension and checking the “Disable Automatic Validation” option. This will prevent XMLSpy® 2010 from validating your XML file against the DTD/Schema it has been assigned to. This is useful, when you want to save an invalid file without being asked twice by XMLSpy® 2010 if you are sure that you would like to save the file. However, it is not possible to disable the well-formedness check in XMLSpy® 2010.