[Zope] "Define Permissions" in ZMI Products

[Jeff Gentry]

One more stupid question ...

I've made a few python based external products and am comfortable setting
default permissions with those but this is my first foray into a ZMI based
product.  I've largely followed the ZooExhibit product in the Zope Book
(what I'm trying to do is not at all complex but I wanted something
distributable ... the ZooExhibit really does fit the general pattern of
what I'm trying to do).  I have a folder named 'OETemplate' which mirrors
the 'exhibitTemplate', and when I install an instance of this product that
template works all hunkey-dorey.

What I'd like to do is set some default permissions on some of the objects
inside that template.  Specifically there is a subfolder which I would
like to set default permissions for adding & changing files.  I've found
the "Define Permissions" tab but for the life of me can't really grok the
concept.  I'm getting the sense that perhaps "you can't get there from
here" in what I'm trying to do and that "Define Permissions" is not really
the right task I want to use to set default perms for a folder, but there
is also not a "Security" tab (which is what I originally figured I'd need
to use, I thought that Define Permissions would be to create new
permissions).

Thanks
-J