As you use Outline Editor to change an outline, each change is posted to a separate line that is added to the Modifications tab. The Modifications tab displays changes made to the outline during the current session. The most recent change is at the bottom of the list.
Operations that you perform simultaneously on multiple members are listed in the Modifications tab as one entry. You cannot undo only one part of a multi-member operation.
Outline changes can be undone only in the reverse order that they were executed. You cannot undo all changes listed on the Modifications tab. What changes can and cannot be undone depends on the type and sequence of the changes.
You can undo operations listed on the Modifications tab even after saving the outline in the current Outline Editor session.
To undo changes made to an outline during the current Outline Editor session:
In the Outline Editor window, select the Modifications tab.
Select the change to be undone and select Edit, then Undo.
Note:
Depending on the type and sequence of changes made to the outline, you cannot undo all listed changes.