Things aren't 100% clean yet, but some tweaks are starting to go in to make output pass as XHTML.

If you'd like to test it, set these in your LocalSettings.php:

$wgMimeType = "text/xml"; $wgDocType = "-//W3C//DTD XHTML 1.0 Transitional//EN"; $wgDTD = "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd";

Mozilla will let you know immediately when it finds output that's not well-formed XML by freaking out and refusing to show the page. :)

UI markup cleanup is tedious but easy. The parser still may need some tweaking here and there, and particularly clean-up for user-written HTML in wiki pages is an area that needs to be carefully checked.

Someday it might be neat to conform to XHTML 1.0 Strict, but that's a freakier land where things like 'width' and 'height' attributes are forbidden.

-- brion vibber (brion @ pobox.com)