[Zope-CMF] Security Options

[G. Edw. Learned]

I am trying to lay out my first major site using the CMF, and am=
 
wrestling with the best way to handle security and structure. I=
 have 
a situation the site will be accessed by different groups of=
 people, 
each group having different access. For example, I might have the=
 
following folder structure:

Topic A
  - Topic A1
  - Topic A2
Topic B
  - Topic B1
Topic C

and so on. Eacj topic will have about 90% of the files and=
 content 
available to everyone, and 10% may vary by group (for example,=
 Group 
1 might see 2 documents, and Group 2 might have 2 seperate=
 versions 
of the same document available to them). 

What I have considered is using document level security and=
 putting 
everything under the single set of folders, as well as having 
seperate folders for each group and using zcatalog to pull the 
information together. I haven't yet managed to get my arms around=
 
what would be the cleanest approach for something like this=
 however.

Any suggestions on structure/security options I should consider?

Thanks
Ed