[From Builder AU
The Oracle database has long had the ability to audit selected types of operations against the database, storing the audit trail in a system table. This table, SYS.AUD$, resides in the data dictionary. On some operating systems, you can also write audit records to the operating system's own event logging subsystem.
Oracle 10g added a third option: The ability to write to files in an operating system directory. These files can be written in XML.
The article continues at