Pl/E stands for plotting/editing. Options screen will plot to the screen or a file, respectively. The AUTO button plots "silently" while running the "plotted" data through a median filter for outliers. ZERO flags all data with zero values, and is more of historical interest than being useful. Beware of accidentally flagging data with these two buttons as you would have to undo this command using Reduce|PointData|Flagtable|UNFLAG and selecting the last entry.