my $t = XML::Twig->new(
    twig_roots => {'nitf/body/body.head/hedline/hl1' => \&fix_hl1,
                   'nitf/body/body.head/hedline/hl2' => \&fix_hl2,
                    _default_ => \&fixup,
                  },
        twig_print_outside_roots => 1,
        keep_encoding => 1,
);