I noticed that new MediaWiki installations have a new meta tag which is
not in the HTML specification and means that MediaWiki sites cannot be
made W3C compliant.
For example, running the validator over
mediawiki.org gives the
following error (amongst a few others complaining about deprecrated
cellpaddign etc):
"Bad value ResourceLoaderDynamicStyles for attribute name on element
meta: Keyword resourceloaderdynamicstyles is not registered."
Would it be worth creating a short description page about the tag in
mediawiki.org and registering it on
http://wiki.whatwg.org/wiki/MetaExtensions to propose it be included in
the specification?