use strict;
use warnings;

use Tie::IxHash;
tie my %hash, "Tie::IxHash";
%hash = (
    Number  => '11',
    EX      => 'ArraySite',
    AM      => 'IOPort',
    PLE     => 'AddressGroup',
);
for (keys %hash) { print "$_ => $hash{$_}\n" }

__END__

Number => 11
EX => ArraySite
AM => IOPort
PLE => AddressGroup