Search notes:

Oracle: init parameter EVENT

Numeric events

Format:

NNNNN trace name context forever, level L

NNNNN and L are numbers.

Multiple events can be separated by a colon:

alter system set event='10325 trace name context forever, level 10:10015 trace name context forever, level 1' scope=spfile;

Named events have a different format.

alter session set events 'immediate trace name controlf level 2' ;
alter system  set events '942 trace name errorstack level 3';

Note the plural events vs the singular event and the missing , before the level.

alter system reset event scope=spfile sid='*' ;

The asterisk (*) does not work for RACs, instead, the instance name is required.

Oracle uses ksdpec() to check if aspecific event is turned on for tracing (if at least one event is set).

ss_wrtf() seems to be related to writing trace files.