Arbortext IsoDraw > User's Reference > Menus > Edit Menu > Preferences > Miscellaneous > Steps for Undo
  
Steps for Undo
Here you enter the max. number of operations which can be undone.
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The number of operations which can be undone is treated as a program preference.
Arbortext IsoDraw saves as many operations as you specify at this point. You can use the menu commands Undo and Redo to undo these operations in the reverse sequence or steps or to redo them after they have been undone (for further information refer to the descriptions in these sections).
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Increasing the number of operations does not have any retroactive effect. In other words, you cannot cause operations to be saved which are older than the number of steps originally set.
Since saving earlier operations can be very memory-intensive, you should not set the number too high. It is generally advisable to limit the number of steps to be undone to three.