Hidden meta data

Some interesting (and lengthy!) debate on JISCmaillast week about hidden meta data on documents created in appliactions such as MS word - could it be accidently released and should it be unless an exemption can be found?

Some relevant links

http://www.itsecurity.com/papers/workshare1.htm

http://office.microsoft.com/en-us/assistance/HA010776461033.aspx