function getID(id){
    return window.document.getElementById?window.document.getElementById(id):null;
}

function fn_showTable(tid){
    for(var i=1;i<=3;i++){
        getID("T"+i).className = "top_close";
        getID("Tbl"+i).style.display = "none";    
    }
    getID(tid).className = "top_open";
    getID(tid.replace("T","Tbl")).style.display = "";
}