The sort is a mistake. Just keeping you on your toes. Now, no one's gonna believe this but ......... I'm sure while trying to solve this problem I wrote the following code

my @keys = ( qw|a e i o u| );
my @records = ();
push @records, '1|2|3|d|4';
push @records, '1|2|3|a|4';
push @records, '1|2|3|d|4';
push @records, '1|2|3|o|4';

my @final = ();
my @result = ();
@result = map { my $index = $_;
                grep{ m/^\d\|\d\|\d\|$keys[$index]\|\d$/ } @records
              } 0..$#keys;
print map{ "$result[$_]\n" } 0..$#result
[download]

which didn;t work. And while replying to your soln, I just re-ran that code and it worked!!!!!!! Hmmmmmmmmmm. Thank you all for replying anyway. I feel such a fool. -Ants