#! perl
use strict;
use warnings;
use Data::Dump;

my @array3d =
(
    [
        [ 'a', 'c', 'e', ],
        [ 'f', 'h', 'j', ],
        [ 'k', 'm', 'o', ],
    ],
    [
        [ 'A', 'C', 'E', ],
        [ 'F', 'H', 'J', ],
        [ 'K', 'M', 'O', ],
    ],
);

dd \@array3d;
my $array_ref = multi(\@array3d);
dd $array_ref;
print "$array_ref->[0][2][1]\n";
       $array_ref->[0][2][1] = 'Change 2';
dd $array_ref;

sub multi
{
    my ($array3d_ref) = @_;

    $array3d_ref->[1][1][2] = 'Change 1';

    return $array3d_ref;
}