RED signal
1. [A] Telecommunications or automated information system signal that would divulge classified information if recovered and analyzed. [NIS]
2. In cryptographic systems, a signal containing classified information that has NOT been encrypted.
3. Any electronic emission (e.g., plain text, key, key stream, subkey stream, initial fill, or control signal) that would divulge national security information if recovered. [INFOSEC-99]