my @sorted = map {$_->[0]} sort {$a->[1] <=> $b->[1] ||
             $a->[2] <=> $b->[2] || $a->[3] <=> $b->[3] ||
             $a->[4] <=> $b->[4]} map {
             [$_, split(/\./, (split /\s+/, $_)[1])]} @lines;
print "$_\n" for @{$row_ref};