function toggle(submenu) 
   {
	if (document.getElementById(submenu).style.display == "none")
	document.getElementById(submenu).style.display = "block";
        else if (document.getElementById(submenu).style.display == "block")
        document.getElementById(submenu).style.display = "none"
        else alert("An error occured in the menu. Contact the web master.");
   }