[Zope] Derivation from DTML document

Hello, I'm planing to write a new ZClass derived from DTML Document. The initialisation of an instance of this ZClass (MyDocument for instance) should contain the selection of some certain keywords, which would be added in the meta tags of the resulting html output. I just want to make sure that there is no such thing I'm looking for and that I will not reinvent the wheel. Kind regards Andreas.