The combat readiness protocol of Enterprise NX-01, devised by Malcolm Reed to bring weapons, hull plating and crew to battle stations with a single order.
Before tactical alert existed, the crew of Enterprise prepared for combat by a string of separate commands. In the episode Singularity, radiation from a trinary star system makes everyone aboard obsess over trivial tasks, and armoury officer Malcolm Reed throws himself into designing a unified security protocol with a blaring klaxon.
Once the crisis passes, Archer decides the idea has merit. Trip Tucker jokes that it should be called a Reed alert, but it enters service as tactical alert and is used for the rest of the series, automatically polarising the hull plating and charging weapons.
The protocol is the forerunner of the red alert used aboard later Starfleet ships.