function toggleLayer(whichLayer) {
    if (document.getElementById) {
        // this is the way the standards work
        var style2 = document.getElementById(whichLayer).style;
        style2.display = style2.display? "":"block";
    } else if (document.all) {
        // this is the way old msie versions work
        var style2 = document.all[whichLayer].style;
        style2.display = style2.display? "":"block";
    } else if (document.layers) {
        // this is the way nn4 works
        var style2 = document.layers[whichLayer].style;
        style2.display = style2.display? "":"block";
    }
}