Edit > Undo

Reverses the effects of the previous command.

The two checkboxes control how (or whether) Alias limits the amount of memory it uses to remember undoable events. You turn on one, both, or neither limit.

In general, using the memory limit is better at conserving memory. However, if you sometimes perform commands on large data sets and you want to make sure you will always be able to undo them no matter how much memory they use, use the command limit instead.

TipIn the long run, it is always preferable to increase the amount of memory in your computer, if possible, than to lose the ability to undo.

Limit number of undo commands: Limits the number of steps you can undo. Set the Maximum number of undo commands option to control the maximum number of steps Alias will remember.
Limit memory used by undo: Limits the amount of memory that undoable steps can take up. Set the Maximum memory used by undo option to control the maximum number of megabytes Alias will devote to remembering undo steps.
Maximum number of undo commands: The maximum number of steps you can undo.
Maximum memory used by undo: The maximum number of megabytes of memory Alias will devote to remembering undoable steps.