Classified data must be handled and stored properly based on classification marking and what else?

Classified data must be handles and stored properly based on classification markings, handling caveats and can only be gain access to by individuals with proper clearance, signed approved non-disclosure agreement and need to know. Classified data is chosen by the original classification authority as confidential which information that possibly will rationally be anticipated to cause damage to national security is exposed, secret which is information that could reasonably be anticipated to cause severe damage to national security if exposed and top secret which is information that could reasonably be anticipated to cause exceptionally grave damage to national security if exposed.