User blog comment:Ohmyn0/Making your wiki HTML5 compliant/@comment-70.49.127.65-20120706064911/@comment-2200849-20120706101806

You indeed cannot use some tags in wikitext, but that does not mean MW 1.19 is not HTML 5 compliant. If the pages it generates conform to the standard (or only have minor errors), then it's compliant.