By default, the AllowUndoRedo property is FalseThe Undo and Redo features let you remove or repeat single or multiple actions, but all actions must be undone or redone in the order you did or undid them – you can’t skip actions. For example, if you change the value of three cells in an item and then decide you want to undo the first change you made, you must undo all three changes. To undo an action you need to press Ctrl+Z, while for to redo something you've undone, press Ctrl+Y. The CanUndo property retrieves a value that indicates whether the chart may perform the last Undo operation. The CanRedo property retrieves a value that specifies whether the chart can execute the next operation in the chart's Redo queue. Call the Undo method to Undo the last chart operation. The Redo redoes the next action in the chart's redo queue. The UndoRedoQueueLength property gets or sets the maximum number of Undo/Redo actions that may be stored to the chart's queue, or in other words how many operations the chart's Undo/Redo manager may store. 

The records of the Undo/Redo queue may contain actions in the following format:

• "AddBar;ITEMINDEX;KEY", indicates that a new bar has been created
• "RemoveBar;ITEMINDEX;KEY", indicates that a bar has been removed
• "MoveBar;ITEMINDEX;KEY", indicates that a bar has been moved or resized
• "PercentChange;ITEMINDEX;KEY", indicates that the bar's percent has been changed
• "UpdateBar;ITEMINDEX;KEY", indicates that one or more properties of the bar has been updated (ItemBar property, this operation can be added only using the StartUpdateBar / EndUpdateBar methods)
• "ParentChangeBar;ITEMINDEX;KEY", indicates that the bar's parent has been changed
• "GroupBars;ITEMINDEXA;KEYA;STARTA;ITEMINDEXB;KEYB;STARTB", specifies that two bars has been grouped
• "UngroupBars;ITEMINDEXA;KEYA;STARTA;ITEMINDEXB;KEYB;STARTB", specifies that two bars has been ungrouped
• "DefineSummaryBars;SUMMARYITEMINDEX;SUMMARYKEY;ITEMINDEX;KEY", indicates that a bar has been defined as a child of a summary bar
• "UndefineSummaryBars;SUMMARYITEMINDEX;SUMMARYKEY;ITEMINDEX;KEY", indicates that a bar has been removed from the summary bar's children
• "AddLink;KEY", indicates that a new link has been created
• "RemoveLink;KEY", indicates that a link has been removed
• "UpdateLink;KEY", specifies that one of more properties of the link has been updated (Link property, this operation can be added only using the StartUpdateLink / EndUpdateLink methods)

The records of the Undo/Redo queue may contain actions in the following format (available starting from 23.0):

• "AddItem;ITEMINDEX", indicates that a new item has been created
• "RemoveItem;ITEMINDEX", indicates that an item has been removed
• "ChangeItemPos;ITEMINDEX", indicates that an item changes its position or / and parent
• "ChangeCellValue;ITEMINDEX;CELLINDEX", indicates that the cell's value has been changed
• "ChangeCellState;ITEMINDEX;CELLINDEX", indicates that the cell's state has been changed

Also, the Undo/Redo queue may include:

• "StartBlock", specifies that a block of operations begins
• "EndBlock", specifies that a block of operations ends

The ChartStartChanging(exUndo/exRedo) / ChartEndChanging(exUndo/exRedo) event notifies your application whenever an Undo/Redo operation is performed. The UndoListAction property lists the Undo actions that can be performed in the chart. The RedoListAction property lists the Redo actions that can be performed in the chart. Use the UndoRemoveAction method to remove the last actions from the undo queue. The RedoRemoveAction method removes the first action to be performed if the Redo method is invoked.