The red/black concept, sometimes called the red-black architectureor red/black engineering,refers to the careful segregation in cryptographic systems of signals that contain sensitive or classified plaintext information (red signals) from those that carry encrypted information, or ciphertext (black signals). In NSA jargon, encryption devices are often called blackers, because they convert red signals to black. TEMPEST standards spelled out in NSTISSAM Tempest/2-95 specify shielding or a minimum physical distance between wires or equipment carrying or processing red and black signals.