Under Split

The "Under Split" was a two-starfighter manoeuvre used by pilots of the Galactic Empire's TIE/ln space superiority starfighters. The move used one fighter as a decoy in order to draw in an opponent, allowing the decoy's wingmate to drop behind the enemy and open fire. The move made the most of the fact that Imperial TIE fighters usually had superior numbers in battle; however, due to the TIE's lack of deflector shields the manoeuvre was risky and left the decoy vulnerable. This risk was deemed acceptable, as overall any loses were deemed inconsequential to the Empire.

Behind the scenes
The "Under Split" was first mentioned in the new canon in the one-hundredth issue of the Star Wars: Build the Millennium Falcon magazine series, which was released in 2016. The manoeuvre was originally created in the 1990 Star Wars Legends Rebel Alliance Sourcebook, which was written by Paul Murphy and released by West End Games as part of Star Wars: The Roleplaying Game.