i think it's how good distant mesh looks (when it fades from really good, to not so good, to low res & when it fades) my distant land (mountains ect) look quite good. i set my values to
always keep a good copy of ur .ini file, then use trial & error, tjhats all I do, then you can find the right settings for you/you're pc. no point in copying other peoples settings in my opinion.
I selected Ultra from the Options menu, nothing modified in the .ini file, it's stock. And other people have on their stock .ini file that 10000000.0000 value.