The main reason why all users must be positively identified prior to using multi-user computers is to ensure that unauthorized persons cannot access the computers. Positive identification is the process of verifying the identity of a user or a device before granting access to a system or a resource2. Positive identification can be achieved by using one or more factors of authentication, such as something the user knows, has, or is. Positive identification can enhance the security and accountability of the system, and prevent unauthorized or malicious access. Providing access to system privileges, providing access to the operating system, and ensuring that management knows what users are currently logged on are not the primary reasons why all users must be positively identified prior to using multi-user computers, as they are more related to the functionality or administration of the system, rather than the security. References: 2: CISSP For Dummies, 7th Edition, Chapter 4, page 89.