function turnon(imgName) {
                if ((navigator.appName=="Netscape" && parseInt(navigator.appVersion)>=3) || (navigator.appName=="Microsoft Internet Explorer" && parseInt(navigator.appVersion)>=4)) {
                imgOn = eval(imgName + "x.src");
                document[imgName].src = imgOn;
        }
}

function turnoff(imgName) {
             if ((navigator.appName=="Netscape" && parseInt(navigator.appVersion)>=3) || (navigator.appName=="Microsoft Internet Explorer" && parseInt(navigator.appVersion)>=4)) {
                imgOff = eval(imgName + ".src");
                document[imgName].src = imgOff;
        }
}