Before revision:  It also provides constant-time support for all the operations provided by different approaches in previous work, as well as new operations that allow us to retrieve the last internal node before or the firstinternal node after a given node in a level-order traversal .
After revision:  It also provides constant-time support for all the operations provided by different approaches in previous work, as well as mapping to and from level-order ranks and retrieving the last (first) internal node before (after) a given node in a level-order traversal .