Removable Secondary Storage Media Devices, such as those shown here, are now prohibited on all classified and unclassified Marine Corps networks by direction of the Marine Corps Network Operations and Security Center, Marine Corps Enterprise Network Operational Directive 293-08. - Removable Secondary Storage Media Devices, such as those shown here, are now prohibited on all classified and unclassified Marine Corps networks by direction of the Marine Corps Network Operations and Security Center, Marine Corps Enterprise Network Operational Directive 293-08.