// initialiseren van variabelen
    cindex = -1;
    naam_old = -1;
    // browsercontrole
    app = navigator.appName;
    ver = navigator.appVersion;
    mac = ver.indexOf("Macintosh") > 0;
    win = ver.indexOf("Win") > 0;
    vnum = parseFloat(ver);
     magOok = (((app == "Netscape") && (vnum >= 3 )) ||
           ((mac) && (app == "Microsoft Internet Explorer") && (vnum >= 3.01 )) ||
           ((win) && (app == "Microsoft Internet Explorer") && (vnum >= 4 ))) ;
 
// als de browser rollovers kan laten zien dan de array met plaatjes aanmaken
     if (magOok) 
             {
// vul het aantal roll-over plaatjes-1 in (hier dus aantal -1 = 7)
              off = new MakeImageArray(3);
              over = new MakeImageArray(3);
              down = new MakeImageArray(3);
                
// vul hier de off-toestand van de plaatjes in
               off[0].src = "images/home-off.jpg";
               off[1].src = "images/contact-off.jpg";
			   off[2].src = "images/notuleerserv-off.jpg";
			   off[3].src = "images/ondersteuning-off.jpg";
			  

// vul hier de over-toestand in
               over[0].src = "images/home-over.jpg";
               over[1].src = "images/contact-over.jpg";
			   over[2].src = "images/notuleerserv-over.jpg";
			   over[3].src = "images/ondersteuning-over.jpg";

// en ook de down-toestand
               down[0].src = "images/home-down.jpg";
               down[1].src = "images/contact-down.jpg";
			   down[2].src = "images/notuleerserv-down.jpg";
			   down[3].src = "images/ondersteuning-down.jpg";


    }
    // de browser wordt verteld dattie de plaatjes moet pre-loaden     
    function MakeImageArray(n) {
        this.length = n;
        for (var i = 0; i<=n; i++) {
            this[i] = new Image();
        }
        return this;
    }
    // de roll-over functie
    function mOver(num,pos) {
        if (document.images) {
            if ((over[num].src != "") && (num != cindex)) {
                document.images[pos].src = over[num].src;
            }
        }
    }
    // de opruim functie
    function mOut(num,pos) {
        if (document.images) {
            if ((off[num].src != "") && (num != cindex)) {
                document.images[pos].src = off[num].src;
            }
        }                   
    }
    // en de klik-functie
    function mClick(num,pos) {
        if (document.images) {
            if ((down[num].src != "")) {
                if (cindex != -1) {
                    document.images[naam_old].src = off[cindex].src;
                }
                document.images[pos].src = down[num].src;
                cindex = num;
                naam_old = pos;
            }
        }
    }