[Zope] Permissions: A question

[robert rottermann]

Hi there,

in CMF the rigth to add content is controlled by the permission "Add 
portal content"

When I create my own portal type, say RR_content it gets automatically the
"Add RR_contents"
permission assigned .

However I have the impression that to add portal content this permission 
is not taken into accout.
It is still enough to have the permission "Add portal content"

Do I miss something here ?
What is that automatic permission for ??

thanks
Robert