function showTariff(id){	
    var table = document.getElementById("formtable"); 
    var rows = table.getElementsByTagName("tr"); 
    for (var i = 0; i < rows.length; i++) { 
        if( rows[i].hasAttribute("parent") ) { 
            parent = rows[i].getAttribute("parent"); 
            if(id==parent || parent==0) {
                rows[i].style.display = "";	
            } else {
                rows[i].style.display = "none";	
            }
        }
    }
}