Codes... and stuff.
Ferengi signal code that used alternating patterns of light and dark to transmit simple text messages.
Starfleet designation for a declaration of war.
TOS: Errand of Mercy
Code 1 Emergency
Federation signal for a total disaster, requiring an immediate response.
TOS: The Trouble with Tribbles
Starfleet encryption protocol. By 2267, the Romulans were able to decrypt Code 2.
TOS: The Deadly Years
Term designating a Starfleet subspace communiqué of extremely high sensitivity or secrecy. Intended only for the eyes of a commanding officer, and voiceprint identification is required. Further, no computer records are maintained of these transmissions.
Interstellar code prohibiting a spacecraft from approaching a planet.
TOS: A Taste of Armageddon
Code Factor 1
Starfleet code meaning invasion status.
TOS: The Alternative Factor
Code One Alpha Zero
Signal indicating the discovery of a space vehicle in distress.
Message encryption protocol used by the Cardassians.
DS9: In Purgatory's Shadow
Very sophisticated, virtually unbreakable computer encryption technique.
Star Trek VIII: First Contact
In a Federation starship's computer systems, the prefix code was a security passcode appended to computer commands to prevent unauthorized activation or control of key systems.
Star Trek II: The Wrath of Khan
Security access code
Password used by Starfleet personnel to provide positive identification when requesting restricted computer functions. Both the password and the user's voiceprint are used to confirm the user's identity. Security access codes are changed occasionally.
TNG: Unnatural Selection
Transporter code 14
Command for an object to be dematerialized, then immediately re-materialized in a dissociated condition, effectively destroying the object.
TNG: Captain's Holiday