function showhidelayer(layer_ref) {
	
	hza = document.getElementById(layer_ref);
	state = hza.style.display;
		
	if (state == 'block') {
		hza.style.display = 'none';
	}
	else {
		hza.style.display = 'block';
	}
}

function showlayer(layer_ref) {
	
	hza = document.getElementById(layer_ref);
	hza.style.display = 'block';
}

function hidelayer(layer_ref) {
	
	hza = document.getElementById(layer_ref);
	hza.style.display = 'none';
}