but it doesn't have any XHTML-specific features. If you want to code in XHTML you'll need to ensure that all tags and attributes are entered in lower case:-
Go to Tools, click on 'Page Options', and click the Code Formatting tab. Make sure that the following check boxes are selected:
Tag names are lowercase
Attribute names are lowercase
End tags are required, so make sure that the 'Omit end tags' check box is deselected.