WebReports Logging Levels

I have enabled logging for our instance of WebReports, but there aren’t descriptions of the 5 different logging levels available. Does anyone have any additional insight as to what each level means? The options are “debug | critical | memory | store_usage | all, where all is the default”.

http://www.ibm.com/support/knowledgecenter/SS6MER_9.5.0/com.ibm.bigfix.doc/Platform/Web_Reports/c_logging_web_reports.html