ce supports an undo/redo facility. It saves information about all commands that modified a given buffer, so that these commands can be undone. Each buffer has its own set of undo records. ce treats consecutive typing of normal (non-command) keys as a single operation; this makes it less tedious to undo large amounts of typing.

The most recent undo operation(s) can be reversed with the redo command. By using undo and redo in succession, you can go backwards and forwards in time through the recent history of a buffer. But if you modify the buffer in any way other than through undo or redo, the ability to redo will be lost until another undo is performed. This prevents conflicting changes from being made to a buffer.

C-X U, F5 (undo)

This command undoes the most recent operation that modified the current buffer. On PCs, this function is also bound to F5.

F7 (redo)

This command undoes the most recent undo.