RMAN-06253: string string string
Cause: An unlogged change (such as 'create table unrecoverable') has been made to this file, and the most recent backup of the file does not contain those changes.
Action: Take a backup of this file. If this file is lost before a backup is taken, then the unlogged modifications will be lost. The message indicates whether a full backup is required or whether a incremental backup will suffice.