var state = 'none'; 

function showhide(layer_ref) { 
	if (state == 'block') { 
	state = 'none'; 
	} 
	else { 
	state = 'block'; 
	} 
	if (document.all) { //IS IE 4 or 5 (or 6 beta) 
		eval( "document.all." + layer_ref + ".style.display = state"); 
	} 
	if (document.layers) { //IS NETSCAPE 4 or below 
		document.layers[layer_ref].display = state; 
	} 
	if (document.getElementById &&!document.all) { 
		hza = document.getElementById(layer_ref); 
		hza.style.display = state; 
	} 
}