PmWiki markup [[<<]] is rendered as <br clear=all /> which is not XHTML1 strict. Perhaps it could be changed to ## [[<<]] (break) Markup('[[<<]]','inline','/\\[\\[<<\\]\\]/',"<br class='clearall' />"); and class clearall added to $HTMLStylesFmt['markup'] as .clearall { clear:both; } or defined as <br style='clear:both' /> ~Hans