[Zope] Properties container: Descend from Folder or DTMLDocument?

Hi, all I am working on a ZClasses thing that makes forms and automagically saves form data into the ZODB. I am assuming the response record (After the 'submit' button is pressed) will be written once (e.g, a test or survey) and changed rarely or never, so it is proper to use the ZODB. I do not want to use a DB product, since if you change the form, you need to modify the table, and that is not nice, either. So, what I want is a thing that just has Properties I can add at runtime. Should this new ZClass descend from Folder or DTMLDocument? From the application's point of view, they are equivalently good, since both have Properties I can modify. Technically, though, which would be better? -- Jim Washington