[ubuntu] chmod question: the "+"at the end of "rwx"

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http://ubuntuforums.org – I've almost got zoneminder working and i'm sure its just a case of changing video permissions!.. I've installed zoneminder on my laptop and also on a server (ubuntu 12.04)... zoneminder is working fine on the laptop or local host with these video permissions: crw-rw----+ 1 root video but on the server which i can't get working yet, video has these permissions: crw-rw---- 1 root video I don't understand what the + is at the end of the owner, group, and everyone else permissions. There is one other thing which may or may not have anything to do with it, i added user www-data to vi (Hardware)