How exactly is sequential download ordered?

[dragons4life]

Is it by name? because there has been a bunch of times where it displays the correct name sorting, but fails to download sequentially (it's not because of seeders, I am sure of it), so what exactly order does it follow? would it be bad to have the user chose the order?

[impetus_maximus]

i think it's by piece. if you click the general tab, you can watch the pieces download from left to right.