XHTML 1.1 is a minor update to the original XHTML specification, in which previously deprecated elements were removed and XHTML 1.0 was modularized into a collection of abstract modules that provide specific types of functionality.
I have a WordPress template that contains the following element: <html xmlns="http://www.w3.org/1999/xhtml" <?php …
php wordpress w3c-validation xml-attribute xhtml-1.1