> This is basically using access control lists to mimic a capability system Is it? My understanding is access control lists are typically static, and on resour

> This is basically using access control lists to mimic a capability system Is it? My understanding is access control lists are typically static, and on resources, defining what is allowed to access them, or on processes/threads/etc, defining what they are allowed to access. If you get a capability from something, and that something eventually becomes invalid, making the capability invalid, is keeping track of that necessarily an access control list? Is any data structure double-checking operations like that always necessarily an access control list? If each capability has a reference to a parent that it relies on to remain valid, does that mean each capability stores an access control list for itself? If your answer to all of these is "yes, that's an access control list" then my response would be to start ignoring the presence of an access control list as it ceases to mean much of anything.