my $balance30elt = new XML::Twig::Elt('BAL_30', $balance30);
    $balance30elt->set_text($balance30);
    $balance30elt->set_att(Period => 1);
    $balance30elt->paste('first_child', $balance);
##</code><code>##

    $balance->insert_new_elt( first_child,     # position
                              'BAL_30',        # tag
                              { Period => 1 }, # attributes
                              $balance,        # content
                            );
##</code><code>##

   $balance->first_child( 'BAL_30') # get the element
           ->del_atts               # if it had atts originally
           ->set_att( Period => 1)
           ;