I am looking to gain better practical knowledge of using ALTER SYSTEM SET EVENTS. It has helped me in trapping and ORA-nnnn errors in the past. For instance, I implemented it using a command given to me by MetaLink to provide more detail on some ORA-2291 errors I was receiving. Great stuff! I'd like to really understand what is possible and the different: modes, events and event levels. Unfortunately it does not seem to be documented very well (or my search criteria was not adequate).
Provide detailed information on using ALTER SYSTEM SET EVENTS.