The measurement(s) the parameters are computed from can be selected below. Either one or two measurements are used, dependent on what parameter is to be computed.
The button can be used to open a measurement from file, if it is not available in the list.
When this dialog is opened, the upper measurement is set to the active measurement. If the window contains two plots, the upper measurement is set to the active measurement in the upper plot. The lower measurement is set to the active measurement in the lower plot.