What is the cutoff-range-multiplier setting?

In Neverwinter Nights Enhanced Edition’s settings.tml, there is a setting that looks like
cutoff-range-multiplier = 2.0000000000000000
(the indentation isn’t showing, for whatever reason)

I am trying to resolve the “black curtain” issue and thought that this setting has potential. Does anyone know what it does?

And, more generally, is there perhaps some documentation or a guide somewhere to the settings in settings.tml? I know some of it is described in the NWN Wiki, but much is missing. I would find more comprehensive documentation to be very useful.