If you delete a derived view (section, detail, or auxiliary) from a drawing, you can reuse the letters from the deleted view in the drawing without manually relettering the views. This option is off by default.
In previous releases, if you deleted a derived view, such as a section view, and then created a new section view, the lettering would use the next sequential letter. For example, if you deleted Section A-A from a drawing view and then created a new section view, the new label would be Section B-B. You can now reuse the letters from deleted views automatically, so the newly created section would be Section A-A.