use Data::Dumper;
use Tie::IxHash;
tie my %list1, 'Tie::IxHash' ;
tie my %list2, 'Tie::IxHash' ;
tie my %hnr, 'Tie::IxHash' ;

%list1 = ( 'ZOP',undef,'AP',undef, 'Exit', undef );
%list2 = ( 'Dev',undef, 'Con', undef, 'Test', undef, 'Exit', undef, 'New', undef);
$hnr{'MAIN'} = { %list1 };
$hnr{'MAIN'}{'ZOP'} = { %list2 };
$hnr{'MAIN'}{'AP'} = { %list2 };

print Dumper(\%hnr);