User blog comment:Ohmyn0/Making your wiki HTML5 compliant/@comment-3527172-20120706044146/@comment-2200849-20120706102018

HTML 4 is obsolete and aging. Those tags that are written out as obsolete have been obsolete in XHTML 1.0 Strict (which Monobook uses), a W3C Recommendation since 26 January, 2000.