Lambda the Ultimate

...traditional continuations are not useful in the presence of concurrency, because the notion of the rest of the computation represented by a continuation does not in general make sense...

Subcontinuations may be used to control tree-structured concurrency by allowing nonlocal exits to arbitrary points in a process tree and allowing the capture of a subtree of a computation as a composable continuation for later use.

Strangely enough this paper wasn't discussed here, even though it was mentioned in the discussion group a long time ago. Now's the time to rectify this omission.