[Zope3-Users] ForbiddenAttribute or unknown attribute?

[Christophe Combelles]

In the link below, it is said that the ForbiddenAttribute exception is ALWAYS a 
problem of permission.
http://kpug.zwiki.org/Zope3Faq#what-is-forbiddenattribute-exception-error

But if you try to access an attribute that simply does not exist, you also get 
this error. In this case, it is has nothing to do with permission.

Is there no UnknowAttribute error?