parse_xml( $xmlfile);

sub parse_xml
  { my( $file)= @_;
    my $ups_able_info= [];
    my $twig1 = XML::Twig->new( twig_handlers => 
                           { 'ups:TABLE_INFO/ups:field' => sub { parse_table_info( @_, $ups_able_info); }
                              )
                         ->parsefile( $file);
    # now $ups_table_info is filled
  }

sub parse_table_info
  { my( $twig, $table_info, $ups_able_info)= @_; # note the extra argument
    my $table_column = {};
    $table_column->{$table_info->field('ups:tag')}  = $table_info->field('ups:ui_name');
    push(@{$ups_table_info}, $table_column);
  }