Keypad backlight LEDs adjustments

[drmark12pa]

I just recently purchased several engraved keypad buttons and am trying to understand the programming of the backlight LEDs settings.  I've attached a picture of the menu for adjusting these settings but I can't find any documentation that explains what these adjustments mean.  I'm basically trying to adjust the backlighting so that at night, the levels tone down a bit but not to the point where you can't see the engraving which seems to be the case if the settings are too low.  However, some of my keypads could have the backlighting turned off during the day or when the room lights are on.