McDermott International Inc. (MCDIF)

[StihlsawsRule]

IMO it means you keep 'the right' to sue 'the estate' on a personal basis. My guess is they have some kind of legal form where you can 'opt in' to whatever joke peanuts settlement that they may have to 'offer' shareholders at the end of the day, just to make litigation go away. Standard BK stuff.
Hope that helps, I could be wrong, but Im pretty sure its something along those lines. Call the US trustee and find out for sure.