if (document.images)
   {
     pic1on= new Image(48,17);
     pic1on.src="gifs/on1.jpg";       
     pic3on= new Image(111,17);
     pic3on.src="gifs/on3.jpg";       
     pic4on= new Image(139,17);
     pic4on.src="gifs/on4.jpg";       
     pic5on= new Image(145,17);
     pic5on.src="gifs/on5.jpg";       
     
     pic1off= new Image(48,17);
     pic1off.src="gifs/off1.jpg";
     pic3off= new Image(11,17);
     pic3off.src="gifs/off3.jpg";
     pic4off= new Image(139,17);
     pic4off.src="gifs/off4.jpg";
     pic5off= new Image(147,17);
     pic5off.src="gifs/off5.jpg";
   }

function lightup(imgName)
 {
   if (document.images)
    {
      imgOn=eval(imgName + "on.src");
      document[imgName].src= imgOn;
    }
 }

function turnoff(imgName)
 {
   if (document.images)
    {
      imgOff=eval(imgName + "off.src");
      document[imgName].src= imgOff;
    }
 }