/me nods ...

In which case, if careful research into the problem confirms that,:

• Yes, that dash is legitimate data, and
• there is no bug either in this program or in the upstream source, and
• the downstream program(s) will know what to do, and therefore,
• here is how we wish to sort it,

... (heh) ...

Then, as you know, the Perl sort verb relies upon a subroutine to do the sort-comparison, “and this is why.”   Although it is most frequently a “one-liner,” it can be a much more elaborate thing which receives two parameters, $a and $b.   (And, if you do several sorts the same way, it can be a separate, not-inline, subroutine that all of them use.)   All of which is well and good ... but I think that I’m in the majority thinking that a bug .. somewhere upstream .. has been uncovered here.