Unless you wish to use both file extensions in order to differentiate between serving MIME/Content types. For instance I use .htm extensions to serve my W3C HTML/ISO-HTML pages as text/html and then have included .......... AddType application/xhtml+xml html ......... in my .htaccess file in order to use the .html extension for XHTML pages thereby serving them as application/xhtml+xml documents if I wish to have XML functionality. I use server side PHP code to serve Content Negotiation pages -- with .php extensions. James