If there is no log file, then the message is written to the correlator’s standard output stream stdout.
The Expression result must be of type 
string. The value is written only if the current logging level in effect is a priority equal to or higher than the 
logLevel specified in the 
log statement, with the exception of 
OFF. If you do not specify a level, 
CRIT, the highest priority level, is used. At a 
logLevel equal to 
OFF, only logs explicitly set to this level will be written. For details, see 
Logging and printing in 
Developing Apama Applications in EPL.