Let me try to explain it clearer then
I read your article about permissions, and I will try to use your terminology.
First your questions, I am talking about web-users, so the front-end. Sorry for not using right terminology in my first post. I will try to answer your second question with an example:
Lets say I have 20 users, and three different user groups. The first group is low-permission, the second middle-permission and the last is high-permission. I will put four users in low-permission, 7 in middle-permission and 9 in high-permission. High permission will be able to see all documents, middle permission all except those tagged as high-permission and low permission only documents that are tagged low-permission.
Following up I will create three resource groups. First is low-permission-doc, second is middle-permission-doc and last is high-permission-doc. I will create 50 documents and place 17 in low-permission-doc, 10 in middle-permission-doc abd 23 in high-permission doc.
Next thing will be to link low-permission to low-permission-doc, middle-permission to low-permission-doc and middle-permission-doc, high-permission to low-permission-doc, middle-permission-doc and high-permission-doc.
So far so good, everything works perfect:)
But now I want to give user12, who is middle-permission, the exclusive right to see doc51. So he will be able to see it, but no-one else will. However it might happen, that I want to give another user the right to see this document. Since in theory this is possible for all combinations of document, creating a new user group for each user is not an option, since i will have 50! possibilities on how to divide the pages among users. And the plan is to make more resources then 50...
I hope this is a better explanation of my post.