When retrieving experimental data, you may find it useful to try several different combinations of noise substraction, data extraction, grid size, initial guess field, etc., to minimize the FROG error. The FROG log keeps track of each retrieval that was done in the current session (without turning off the program). By selecting a row, and clicking the "Display Log" button, a log file listing all the input parameters to that retrieval is shown, so that you can finalize the retrieval that produced the lowest FROG error.