The REDO command will restore the Editor to the state before the last
UNDO editing operation, which could be any editing command.
A REDO is available for all previous consecutive UNDO commands. However, if the previous editing command is not an UNDO, the REDO will become disabled.
Like UNDO, the Redo only allows recovery for a fixed number (16) of UNDO steps. In other words, the Editor only keeps record for a fixed number of most recent UNDO commands.