var tbl1, tbl2, tbl3, tabs;

function init(){
   //alert ("executing init");
	tbl1 = document.getElementById("tbl1");
	tbl2 = document.getElementById("tbl2");
	tbl3 = document.getElementById("tbl3");
	tabs = document.getElementById("tabs");
}
	function clear_tables() {
	   tbl1.style.display ="none";
	   tbl2.style.display ="none";
	   tbl3.style.display ="none";
	}
	
	function swap(n){
	var tabs = document.getElementById("tabs");

	  eval('tabs.className="c' + n + '";');
	  clear_tables();
	  eval("tbl" + n + ".style.display=''");
	}