To be more explicit about the CSV format:
Now, as for the basic "CSV" style log, there are two formats over time, but I think only the most recent has survived unless you're a die hard VHFer using the WSJT as opposed to WSJT-X.
The format I see in WSJT-X goes like this:
Date, UTC, DXCall, DXGrid, freq, Mode,report_sent,report_rec,power,comment
If it is the older format, then some of the first parameters are in a little different order and it is obvious from inspection which is which once you know the above is what the contents are.
If that's not enough and you want to reverse engineer the log for yourself, make up a phony QSO with unique values for the above and save it (you can manually delete it). The log will then reveal itself to you whatever version of the code you have.