############################
# filename: MyFirstModule.pm

package MyFirstModule;

our %common_codes_hash = (
    '000001' => 'ITEM _First',
    '000002' => 'Item B',
    '000003' => 'House',
    # ....);

1;

__END__

########################
# filename: myscript1.pl

use MyFirstModule;

my $whatever = $MyFirstModule::common_codes_hash{$foo};

# ....

__END__