[Zope] un-renamable objects

How do I make an object un-renameable? I'm developing a product where a certain object has a "forced" id, ie. you can only enter a suitable title when creating an instance. The object uses OFS.Folder.Folder as base class. Peter --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.391 / Virus Database: 222 - Release Date: 2002-09-19