At the moment, actually since end May 2001, XHTML has been updated a little.
First of all XHTML 1.1 is an updated version of XHTML 1.0 strict. So some elements that were only valid for XHTML tranistional and frameset, weren’t valid for XHTML strict and are not valid for XHTML 1.1.
The biggest change is that version 1.1 is now modulized. What this means is that the HTML language is devided in different modules. This allows programmers to write their own versions of the DTDs. This doen’t really affect the normal webdesigners.
Since there is only one version (acutally it is only one DTD, instead of three for XHTML 1.0), there is only one doctype.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
The first doctype is that of XHTML 1.1, the second of XHTML 1.0 strict. As you can see, not that much of a difference.
Another small thing that has changed is the language attribute. It is no longer valid. You should use xml:lang=””. So if you had pages in English the lang=”en” becomes xml:lang=”en”.
A last thing that changed is the name attribute. For both the anchor tag and image map, <a> and <map> respectively, the name attribute isn’t valid anymore. You should now use id.
That’s it. So changing from version 1 tot 1.1 isn’t much work. Most can probably be done by using the replace function in your editor. The main reason for all this, is actually the preparation for XHTML 2 which is only being drafted at the time of this writing.