As a rule, information processing environments of classification level I are recommended to be kept physically separated from all other environments. A typical implementation is an information processing environment physically separated from all other environments, located within a controlled physical security area in a shielded room, and operated with a dedicated terminal device reserved for this purpose. Another possible implementation is an environment located in a shielded room within a security area, consisting of physically separated terminal devices, a local network connecting them, and a dedicated printer reserved for this purpose.

Data transfer to physically separated environments must be implemented in such a way that the risk of classification level I information being transferred into lower classification level environments is minimized.