Selecting Log to file using date as filename saves logged data to files in the REW logs directory automatically whenever the logger is running (the directory location is shown in the About REW dialog box). Filenames are formatted as SPL-YYYY-MMM-dd.txt, e.g. SPL-2016-Apr-24.txt. If a file for a day already exists a number will be appended, e.g. SPL-2016-Apr-24-1.txt, SPL-2016-Apr-24-2.txt etc. A new file is created if the logging continues past midnight, with the new date. Note that the files can become very large if logging continues for a long period, growing at about 18 kB per minute. If the option to log to files is selected remember to check the REW log directory to remove files you no longer need.
My apologies if I sounded gruff before, I didn't mean to come across frustrated.You may want to read a little further into the SPL logger help, to the next paragraph: