A Rollback Segment is an object that Oracle Database uses to store data necessary to reverse, or undo, changes made by transactions.
Note: Oracle recommends that you run your database in automatic undo management mode instead of using rollback segments.
Rollback Segment Editor allows you to define rollback segment properties. It opens automatically when you create a new rollback segment and is available on editing an existing one.
To open a rollback segment in Rollback Segment Editor, double-click it in the DB Explorer tree.