Three of the filtering parameters -- the rectifier baseline and the lower and upper window discriminators -- can be set either by making the appropriate selection from the menu then entering the value, or by using the Visually selection then selecting the levels with the pointing device. When you select Visually, the program asks you whether you want to view just the current analysis range, selected by the "Start of run" and "End of run" parameters, rather than the whole run. Whichever you choose, the waveform is displayed, and the cursor is turned on so you can point to the levels you want.
The window discriminators are used to perform spurious point rejection: all points out of this range are rejected, and replaced with the last valid point. If this is not desired, set them to the minimum and maximum allowed values.
The baseline indicates the level to be used as the "zero" for full-wave rectification. To disable rectification, set it to the minimum allowed level, or just disable the Rectify option.