[jQuery] Sortables (interface plugin)

Hello,
I have a nested list and i'd like to lock the sortable option to the
each level (so that it wouldn't be possible to drag the selected
element to the another level).
I was looking at the documentation on the interface plugin site
(http://interface.eyecon.ro/docs/sort) but i didn't find such an
option...
Does anywan know if this is possible?
I'm also wondering how to submit the resorted list?