function tab(group, tab_id) {
	document.getElementById(group+'1').style.display = "none";
	document.getElementById(group+'2').style.display = "none";
	document.getElementById(group+'3').style.display = "none";
	document.getElementById(group+'4').style.display = "none";
	document.getElementById(tab_id).style.display = "block";
	document.getElementById('b'+group+'1').style.backgroundColor = '#003366';
	document.getElementById('b'+group+'2').style.backgroundColor = '#003366';
	document.getElementById('b'+group+'3').style.backgroundColor = '#003366';
	document.getElementById('b'+group+'4').style.backgroundColor = '#003366';
	document.getElementById('b'+tab_id).style.backgroundColor = '#333';
	}