If I'm reading you right, you want to access a 2D array using textual indices. Something like this

#! perl -slw
use strict;
require 5.008; # For use constant %hash syntax.

use constant {
    LONDON      => 0,
    PARIS       => 1,
    TOKYO       => 2,
    NEW_YORK    => 3,
    MILAN       => 4,
    SAN_PAULO   => 5,
};

use constant {
    FIRST_QUARTER   => 0,
    SECOND_QUARTER  => 1,
    THIRD_QUARTER   => 2,
    FOURTH_QUARTER  => 3,
    TOTAL           => 4,
};

my @sales = map{
   [ map{
       int(rand(10000))/100
   } FIRST_QUARTER .. FOURTH_QUARTER ]
} LONDON .. SAN_PAULO;

for my $city ( LONDON .. SAN_PAULO ) {
    $sales[ $city ][ TOTAL ] += $sales[ $city ][ $_ ] for FIRST_QUARTE
+R .. FOURTH_QUARTER;
}

print "@{ $sales[ $_ ] }[ FIRST_QUARTER .. TOTAL ]" for LONDON .. SAN_
+PAULO;
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The upside is that the constants get translated in-line which is good for efficiency. The downside is that you can't (easily) use them to generate text for display.