In the book named "operating system security", I read this paragraph:
"Protection domains can also be constructed from an intersection of the associated subjects (e.g., Windows 2000 Restricted Contexts [303]). The reason to use an intersection of subjects permissions is to restrict the protection domain to permissions shared by all, rather than giving the protection domain subjects extra permissions that they would not normally possess."
I don't understand the meaning of "intersection of subjects permissions" and how to use this property.Any idea?