function checkBrowser(){
        this.ver=navigator.appVersion
        this.dom=document.getElementById?1:0
        this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom)?1:0;
        this.ie4=(document.all && !this.dom)?1:0;
        this.ns5=(this.dom && parseInt(this.ver) >= 5) ?1:0;
        this.ns4=(document.layers && !this.dom)?1:0;
        this.bw=(this.ie5 || this.ie4 || this.ns4 || this.ns5)
        return this
}
bw=new checkBrowser()

    if (document.images){
                        imag = new Array();
                        imag[0] = "grafiken/but1_a.gif";
                        imag[1] = "grafiken/but1_n.gif";
                        imag[2] = "grafiken/but2_a.gif";
                        imag[3] = "grafiken/but2_n.gif";
                        imag[4] = "grafiken/but3_a.gif";
                        imag[5] = "grafiken/but3_n.gif";
                        imag[6] = "grafiken/but4_a.gif";
                        imag[7] = "grafiken/but4_n.gif";
                        imag[8] = "grafiken/but5_a.gif";
                        imag[9] = "grafiken/but5_n.gif";
                        imag[10] = "grafiken/but6_a.gif";
                        imag[11] = "grafiken/but6_n.gif";
                        imag[12] = "grafiken/but7_a.gif";
                        imag[13] = "grafiken/but7_n.gif";
                        imag[14] = "grafiken/but8_a.gif";
                        imag[15] = "grafiken/but8_n.gif";
                        imag[16] = "grafiken/but9_a.gif";
                        imag[17] = "grafiken/but9_n.gif";

                        im = new Array();
                        for (var i = 0; i <= imag.length; i++)

                        {
                        im[i] = new Image();
                        im[i].src = imag[i];
                        }
                }

                        function toggleImg(imgName,num){
                if (document.images){
                        imgName.src = im[num].src
                }
        }