function showHideLayer(layerName)

{

   new_style = (document.getElementById(layerName).style.display == "none") ? "block" : "none";

   document.getElementById(layerName).style.display = 'block';

   document.getElementById(layerName).style.display = new_style;

}



function hideLayer(layerName)

{

   document.getElementById(layerName).style.display = 'none';

}



function showLayer(layerName)

{

   document.getElementById(layerName).style.display = 'block';

}