The Select Ports dialog box is opened when you click on the Select button in the Ports heading in the Properties section of the Manage Curves dialog box and allows you to select the Ports for your measurement. The dialog box lists all possible port combinations, click on the check box for a combination to select it. You may select multiple combinations, a new curve is created for each combination and all of the curves created are added to a group in the curve list. If you wish to select all of the combinations, select the Selected checkbox at the top of the dialog box.