function showSubmenu (mode,reference) {
   var subMenus = reference.getElementsByTagName("span");
   for (var i=0; i<subMenus.length; i++) {
	var subMenu = subMenus[i];
	if(mode == "over"){
		subMenu.className+=" sfhover";
	}else if(mode == "out"){
		subMenu.className=subMenu.className.replace(new RegExp("sfhover"),"");
	}
   }
};