use strict;

my %packet_fields = (
  'Format_X' => ['ident', 'flags', 'x', 'y', 'mode3'],
  'Format_Y' => ['ident', 'RDP_Ident', 'Radar_Site_Ident', 'site_x']
);

foreach my $format (keys %packet_fields) {
  foreach my $field (@{$packet_fields{$format}}) {    #line 9
    print "$format -> $field\n";
  }
}

foreach my $format (keys %packet_fields) {
  print "$format's 2nd field = ", $packet_fields{$format}->[1], "\n"; #line 15
  print "$format's 3rd field = ", $packet_fields{$format}[2], "\n"; #line 16
}