function imgUp(imgName) {
   if (document.images) {
       document[imgName].src = "https://asdu.fnmoc.navy.mil/ww3_cgi/images/image_btn.gif";
        }
}

function imgDown(imgName) {
        if (document.images) {
            document[imgName].src = "https://asdu.fnmoc.navy.mil/ww3_cgi/images/image_btn_dn.gif";
        }
}