Report is a feature available exclusively in CF Vietnam and on the new CF SEA, allowing players to report hacks and illegal activities using in-game form.
During a match, players can access Pause menu then choose "Report" to report a cheating player within the room. The menu then list all players in room to choose (Both BL and GR), a drop-down menu to choose Reporting reason (Hacking, Cursing/swearing, Server crashing...), and a small info box to enter additional info. Clcking Confirm will send a messenger to the GM center, so they can look into reported player's log to see if there is any suspicious activities.
As promising as it looks, this feature is not very useful due to the warning pop-up right at the start - if you file a false report, you will be blocked permanently. Many players don't even want to try even if they know well that someone is hacking - this is because anything can happen if the GM decides otherwise. Though very popular when it's first updated, Report feature is now obsoleted, as players tend to go directly to CF Vietnam forum to report hacks instead.