function nav(id)
{
	var submenu = d.getElementById('sn_'+id);
	var img = d.getElementById('i_'+id);
	
	if (submenu.style.display == 'block') {
		submenu.style.display = 'none';
		img.src = '/images/top_lvl_link.gif';
	}
	else {
		submenu.style.display = 'block';
		img.src = '/images/top_lvl_hover.gif';
	}
}