First , features available to users in the single user case must also be available in the multiuser case. Cai Linxi and A. Nico Habermann. The linear undo model allows undoing of a sequence of operations and keeps a pointer which tracks the next operation to be undone. Operations can then be redone, after possibly doing some new operations. The linear undo model allows the undoing of a sequence of operations by using a pointer that tracks the next operation to be undone.
Operations can then be redone, after possibly doing some new operations.