[CentOS] How to export X displays

Akemi Yagi wrote:

>>From the Ubuntu box, connect to CentOS by:
> 
> ssh -Y centosbox
> 
> (use -Y instead of -X, see man ssh for the reason)

Does anyone know what that man page means?  That is, what is does 
"trusted" mean in that context?

-- 
   Les Mikesell
    lesmikesell at gmail.com