Explanation:
Cancel-based recovery can be performed when a current online redo log file or all the files of an online redo log group are missing or are corrupt. Cancel-based recovery is used when you apply recovery till then end of a log file. The recovery operations can be terminated at the end of a log by issuing the CANCEL command.
Reference:
Oracle 9i Net Services Administrator’s Guide
Oracle 9i Net Services Reference Guide
Oracle 9i Recovery Manager Reference
Oracle 9i Backup and Recovery Concepts

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