So what is it?
Its an engine function designed to send the bullettraces to the server and create an impact effect at the given position.
If you hook it you can chnage the bullet impact position, also its return value (its a boolean) if you hit something or not.
Hope this helped.
Progress with my game - "Disbanded"
Fixed FPS lag on spawning entities due to the ent_preload buffer!
Edit the AI code to get some better pathfinding
Fixed the view bug within the sniper scope view. The mirror entity is invisible now!
Added a new silencer for ALL weapons. Also fixed the rotation bugs
Added a ton of new weapons and the choice to choose a silencer for every weapon
Created a simple AntiCheat, noobs will cry like hell xD
The name will be Disbanded, the alpha starts on the 18th august 2014
Some new physics fun (Serversided, works on every client)