browser = (((navigator.appName == "Netscape") && (parseInt(navigator.appVersion) >= 3 )) || ((navigator.appName == "Microsoft Internet Explorer") && (parseInt(navigator.appVersion) >= 4 )))
        if ( browser) {

dortn = new Image(24,145);
dortn.src = "image/button4b.jpg";
ucn = new Image(24,145);
ucn.src = "image/button3b.jpg";
ikin = new Image(24,145);
ikin.src = "image/button2b.jpg";
birn = new Image(24,145);
birn.src = "image/button1b.jpg";

dortf = new Image(24,145);
dortf.src = "image/button4a.jpg";
ucf = new Image(24,145);
ucf.src = "image/button3a.jpg";
ikif = new Image(24,145);
ikif.src = "image/button2a.jpg";
birf = new Image(24,145);
birf.src = "image/button1a.jpg";
}
function img_act(imgName) {
        if ( browser) {
imgOn = eval(imgName + "n.src");
document[imgName].src = imgOn;}}
function img_inact(imgName) {
        if ( browser) {
document[imgName].src = eval(imgName + "f.src");
}}