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";
    }
}