function light_on(imgName) {
                if (version >= 3)
                {
                   imgOn = eval(imgName + "on.src");
                   document[imgName].src = imgOn;
                }
        }
   
   
        function light_off(imgName) {
                if (version >= 3)
                {
                   imgOff = eval(imgName + "off.src");
                   document[imgName].src = imgOff;
                }
        }