When you start Intel Monkey log files are created in the "debug" sub-folder. There is a group of files with similar names under _MAIN, then when processes start to read in AE reports other groups are created: _SI and _CR for SigInt and Combat, respectively. The file with the abbreviation is a 'marker' to show which group of logs is which. Notice that the log file names have a date-time stamp in their names so that they sort together in your folder display.
If you need to submit log files for help, send me email george.gillan@gmail.com.
Log files should always be submitted in a group. Here is what the groups look like.
As mentioned above, the file with underscores plus some tag (currently MAIN, CR, or SI) is a marker file used only to provide a visual reference as to which group is which.
The file _errlog contains any software errors emitted.
The file _logfile contains a series of messages deliberately logged by the software giving information about what is happening. Of necessity these messages are very sparse compared to how much the software actually does, but can still be very useful in troubleshooting.
The file _outfile contains various output deliberately made by the software to give much more detailed information than can be accommodated in the _logfile.
Information in the three files often goes hand in hand, so all three are needed. The 'tag file' is not strictly needed but makes identification of the three accompanying files much easier so it best to include it when submitting a group of log files.
In case you wish to further understand how the groups of log files are named, here is a pictorial explanation. Orange text has been added which explains the numbers in the name of a file.