// JavaScript Document

function tab(nm,ba){
	document.getElementById('t1').style.background='url(\'images/understanding/taboff.gif\')';
	document.getElementById('t2').style.background='url(\'images/understanding/taboff.gif\')';
	document.getElementById('t3').style.background='url(\'images/understanding/taboff.gif\')';
	document.getElementById(nm).style.background='url(\'images/understanding/tabon.gif\')';
	
	var bob = Array();
	bob['t1'] = 'lowtier.jpg';
	bob['t2'] = 'midtier.jpg';
	bob['t3'] = 'hightier.jpg';
	
	var img = ("images/understanding/"+bob[nm]);
	document.getElementById('machine').src=img;
	
	document.getElementById('i1').style.display = "none";
	document.getElementById('i2').style.display = "none";
	document.getElementById('i3').style.display = "none";
	
	document.getElementById(ba).style.display = "";
	
}