b_lo = new Image();b_lo.src="images/b.gif";
    b_hi = new Image();b_hi.src="images/b_hi.gif"; 

    function Roll(e,im) 
	 {e.src=im.src;}
 
 function Rollin(id)
 { if (document.getElementById)
  {
   element = 'sub'+id; 
   e = document.getElementById(element);
   e.className="yellow";
  }
 } 
  function Rollout(id)
 { if (document.getElementById)
  {
   element = 'sub'+id; 
   e = document.getElementById(element);
   e.className="black";
  }
 }