function toggleLayer(layerhide,layershow)
{
    if (document.getElementById)
    {
        var style1 = document.getElementById(layerhide).style;
        var style2 = document.getElementById(layershow).style;
        style1.display = 'none';
        style2.display = 'block';
    }
    else if (document.all)
    {
        var style1 = document.all[layerhide].style;
        var style2 = document.all[layershow].style;
        style1.display = 'none';
        style2.display = 'block';
    }
    else if (document.layers)
    {
        var style1 = document.layers[layerhide].style;
        var style2 = document.layers[layershow].style;
        style1.display = 'none';
        style2.display = 'block';
    }
}