my @records;
{
    local $/ = "\n\n";
    open IN, "<file.dat" or die "Cannot open data file.\n$!";
    while ( my $record = <IN> ) {
        my @kv_pairs = split /\n/, $record;
        push @records, [@kv_pairs];
    }
    close IN;
}
my @sorted_recs = map { $_->[0] } 
                  sort { $a->[1] <=> $b->[1] }
                  map { [ $_, (split /:\s*/, $_->[3])[1] ] }
                  @records;