[help] Prevent to delete imap folders or to create a new one

[Marco]

Hi all,
a simple question. I have to deny delete of an imap folder and also to  
create new subfolders.

With cyrus 2.4.6 I tried with these ACLs:

lrswipted

With these the folder deletion has denied, but I can create subfolders again.

How do I can deny creation of new subfolders?

Thank you very much
Regards
Marco