Parameter and Command Reference > Logging Configuration Parameters > LogTypeCSVs 

LogTypeCSVs 
List of message types to log. Type one or more of the following message types to specify the type of messages written to the associated log file. If you want to type multiple message types, separate them with commas (there must be no space before or after a comma):
 
Logs index actions as well as index actions that are sent after IDOL Server has routed incoming data through other processes.
Logs each query term, after stemming, conversion to UTF8, capitalization and punctuation removal. This is mainly used by the Autonomy DiSH server for statistical reports.
Logs UserAdd and UserDelete actions and related messages.
 
LogTypeCSVs=Application,Index