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"Actual" is the wireless callsign for the commanding officer, borrowed from the real-world communications term for the officer-in-charge (e.g. the commander of a military vessel, task force or unit).

It is used to distinguish the commanding officer from other personnel who may use the communications channel, without resorting to a code name or other identification. It is frequently used when sensitive information needs to be communicated directly to the officer-in-charge or when a direct and urgent order must be rendered.

Example: A pilot from battlestar Pacifica, callsign "Joker," is ordered to engage a target.

Pacifica: Joker, Pacifica. Engage the unidentified craft, weapons free.
Pilot: Pacifica, Joker. Confirm.
Pacifica: Joker, Pacifica Actual. Execute the order.

When communicating over wireless aboard Galactica, William Adama is "Galactica actual".