if ($txtfile =~ m/(some associative pattern for each CSV list)/gs)
     {
     my $key = $1;
     while ($txtfile =~ m/(CSV)/gs)
          {
          push @{$hash{$key}}, $1
          }
     }

##</code><code>##

@{$hash{$key}}[0] = 0,1,2,3
@{$hash{$key}}[1] = 4,5
@{$hash{$key}}[2] = 6,7,8,9

##</code><code>##

@{$hash{$key}}[0] = 0,1
@{$hash{$key}}[1] = 2,3
@{$hash{$key}}[2] = 4,5
...