The operating system of the CAP computer designed at Cambridge University in the 1970s, and described at http://www.research.microsoft.com/NeedhamBook/cap.pdf .
http://www.cs.washington.edu/homes/levy/capabook/Chapter5.pdf is the chapter on CAP in LevyBookCapabilityBasedComputerSystems.
Also see CapabilitySecurityModel.
ObjectCapabilityOperatingSystem CategoryOperatingSystem