//  This function changes a layer's visibility based
  //  on whether Navigator or IE is running on system
  function ChangeLayerVisible (LayerName, Visibility)
  {
      if (navigator.appName == 'Netscape')            // check for Netscape
         if (Visibility)
          document.layers[LayerName].visibility = 'show';
        else
          document.layers[LayerName].visibility = 'hide';
      else                                            // otherwise assume IE
      {
        if (Visibility)
                document.all[LayerName].style.visibility = 'visible'
        else
          document.all[LayerName].style.visibility = 'hidden';
      }
  }