Which two are regarding automatic space management segments？（）

Media recovery can sometimes be stopped by the inability to read past a certain point in the redo stream. This is often referred to as “stuck recovery”. Before Oracle9i， the 
Database Administrator had few options to deal with stuck recovery. If the corrupt redo could not be recovered from some other source， then all transactions that committed after the corrupt point in the redo steam would be lost. 
Oracle9i changes that with the Trial Recovery feature. Trial Recover is used to test the application of the redo logs to the database. 
What are three other characteristics of Trial Recovery（）