The Output Stage Circuit Components form displays the pre-load resistor used on the secondary of the power supply.
PI Expert will calculate a default resistor to provide a 1.5mA load to the output.
The pre-load resistor causes the output to discharge below the LED string voltage when the AC is removed. This guarantees that the LEDs completely turn off rather than there being a slight glow for several seconds after AC is removed.
You can change the automatically selected resistor for a created design by clicking the calculator icon 
in the components box. Click change to open the Resistor dialog box and edit the parameters.
The 
icon indicates that a custom parameter value has been entered. Click the icon to restore the default automatically selected value.