BBED> undo
BBED> modify /x 44464341 filename '/disk2/oradata/sydb/tbs03.dbf' block 135. offset 8184.
File: /disk2/oradata/sydb/tbs03.dbf (0)
Block: 135 Offsets: 8184 to 8191 Dba:0x00000000
------------------------------------------------------------------------
44464341 0106abba
<32 bytes per line>
BBED> sum apply
Check value for File 0, Block 135:
current = 0xaf39, required = 0xaf39