Re: [boost] [proposal] Sequence container with O(log n) random access _and_ O(log n) insertion/removal (wherever)

This does look like a valuable addition to the currently available sequence containers, and I would love to see it developed into a boost library. Out of curiosity, since I didn't see it mentioned in previous posts (maybe I'm blind and missed it)... What operations on the container cause existing iterators to be invalidated?