Good questions, all. I didn't address them at first for 2 basic reasons. First, my post was already so long, and second, I haven't the foggiest notion of what I should do.

I guess, in terms of the latter question

$interval = 500;
'I' => {
     $a => [200,500,800],
...
[download]

I guess my thoughts are, it's not *likely* to happen, but can. In that case, I was sort of thinking that if they overlap by $interval/2 or more, then just lump them together. Although, this can be dealt with at a later time.

As for a number appearing in more than 1 list, ideally, again, this wouldn't happen, but I have to assume it will. Always assume the user will f*** up your program somehow, right?

Matt