3. The operating system must protect users from themselves. A user’s application may consist of several modules stored in separate memory locations, each with its own data. One module must not be allowed to destroy or corrupt another module.
4. The operating system must be protected from itself. The operating system is also made up of individual modules. No module should be allowed to destroy or corrupt another module.
5. The operating system must be protected from its environment. In the event of a power failure other disaster, the operating system should be able to achieve a controlled termination of activities from which it can later recover.