How to calculate unique security scopes

Question

I've read the http://technet.microsoft.com/en-us/library/cc262787.aspx and I have problems calculating the number of unique security scopes. For example:
One list:
Two items broken permission can be seen by user a ---> 1 security scope
Two items broken permission can be seen by user b ---> 1 security scope
Two items broken permission can be seen by users a,b ---> 1 security scope
Two items broken permission can be seen by user a and modify by user b---> 1 security scope
Sum of items: 8, overall security scopes in the list: 4
Am I correct?
Thank you
Christos

Answer 1

XristosK,
As per my knowledge
Two items broken permission can be seen by user a ---> 2 security scope (if you are not using a group)
Two items broken permission can be seen by user b ---> 2 security scope (if you are not using a group)
Two items broken permission can be seen by users a,b ---> 2 security scope (if you are not using a group)
Two items broken permission can be seen by user a and modify by user b---> 2 security scope (if you are not using
a group)
Sum of items: 8+, overall security scopes in the list:
8 + List's own security inheritance<what ever>
Read this great article: Scaling to
10,000 unique permissions – Part 1 – The Problem
So what is a Security Scope then? 
To put it simply … each time you grant access to a new principal (user account or group) then you are creating a new Security Scope.
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