function showhide(layer_ref, layer_ref2)
{
	if (document.all)
	{
		eval( "document.all." + layer_ref + ".style.display = 'block'");
		eval( "document.all." + layer_ref2 + ".style.display = 'none'");
	}
	else if (document.layers)
	{
		document.layers[layer_ref].display = 'block';
		document.layers[layer_ref2].display = 'none';
	}	
	else if (document.getElementById && !document.all)
	{
		hza = document.getElementById(layer_ref);
		hza.style.display = 'block';
		hza = document.getElementById(layer_ref2);
		hza.style.display = 'none';
	}
}