var f_id="lab01";
function lab(id){
	if(f_id!=id){
		document.getElementById(f_id).src=document.getElementById(f_id).src.replace("_on","");
		document.getElementById(id).src=document.getElementById(id).src.replace(".gif","_on.gif");
		document.getElementById(f_id+"_d").className="hide";
		document.getElementById(id+"_d").className="";
	}
	f_id=id;
}