etconfig

Setting r_clamptoedge to “0″ removes the fog using ATI video cards, improving a little bit the long range visibility.

Usage:
/seta r_clamptoedge 0
then do:
/vid_restart

Values: “0″ or “1″

Note:
The increased visibility is not much, the area between where the fog begins and ends (which normally is a partially visibile area) is not blocking the view anymore.
It can be a high advantage for some people so this is why most of the servers are restricting it.

As an image examples from www.rtcw.jolt.co.uk:
r_clamptoedge 1
r_clamptoedge 0