The purpose of this handbook is to provide basic guidance to engineers and installers of military departments and agencies in the design and installation of systems and facilities which accept, store, retrieve, manipulate, graph, archive, integrate, and communicate classified information. When selectively applied, its principles support RED/BLACK and TEMPEST programs of the military departments to reduce the risk of clandestine exploitation of classified defense information. Its principles may also be applied to lesser degrees to systems processing unclassified information which may be sensitive due to provisions of public law.