xbig class style XHTML 2nd (eXtensible Hypertext Markup Language) . [See also HTML] attributes id minimizing values CSS DTD elements closing nesting HTML differences 2nd 3rd resources tags names XML 2nd resources tags Web Services 2nd 3rd 4th 5th 6th defined Passport authentication service platforms 2nd two number calculation example 2nd 3rd 4th 5th XML Object Flash