Explanation:
During checkpoints the new online redo log sequence number is written to the headers of every datafile in Oracle, as well as to the control file. In addition to this information, the V#DATAFILE_HEADER view indicates that the datafile is currently being backed up if the FUZZY column contains the word "yes".
Incorrect Answers:
1: This value in the 'FUZZY' column does not show that the data file is corrupted.
2: This value in the 'FUZZY' column has nothing to do with locally managed table spaces.
4: This value in the 'FUZZY' column does not show that the data file is part of a read-only table space.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 594
Chapter 12: Overview of Backup and Recovery

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