This benchmark is based on one of the ingame locations – Marshland. The testing process includes four stages, those utilizing various weather and time of the day settings (day, night, rain, bright sun). In order to test your system thoroughly the benchmark is provided with a number of presets and options including different versions of DirectX (9.0, 10.0, 10.1), screen resolutions, antialiasing etc, all at your disposal. Having your PC tested with S.T.A.L.K.E.R.: Clear Sky benchmark you will be able to get detailed information about its performance on various graphical modes and find out how well your system is balanced for gaming and S.T.A.L.K.E.R.: Clear Sky in particular.
Wait I don't understand - a benchmark? Like a milestone?
It's a tress-test to see how well your computer performs when running the game.