We recommend using one of these editors to create XML formatted files. Of course you can use your own preferred toolkit … (there are better things than old dreadful notepad)
As we often use a different extension (map, fir) than .XML - you probably need to choose the correct file format when opening a FIR definition file.
very powerful but lightweight XML editor, includes XPath query editor, a Pretty-Print function (indentation & formatting) and supports Relax NG schema validation http://xml-copy-editor.sourceforge.net
very powerful XML editor, includes XPath query editor and supports Relax NG schema validation. You need to download the free version http://www.editix.com