Any value to having a negative path?

So I had two lists with identical tree structures I wanted to weave alternately (eg A,B,C and 1,2,3 into A,1,B,2,C,3), so I used target paths in the path mapper to re-write the branches for the lists and then merge the two together. I'm sure there might be a better way to do this, but this works fine. Anyway, I miss-wrote one of the target paths initially and ended up with a negative path, {-1}. 

So I'm wondering if there is any reason why assigning a negative path would ever be advantageous? Or are the path ID's just dumb numbers, meaning it doesn't matter if they are positive or negative, only if they are unique or not?

It's not that understanding this will help my current problem, but I was just curious. Thanks for indulging my inexperience.