The clandestine Sienar Advanced Projects Laboratory, often abbreviated as APL, functioned as a covert design and experimentation center for starfighters, belonging to Sienar Fleet Systems. Situated on the rather isolated and inconspicuous world of Lothal, its location offered a degree of security against potential spies. The initial prototype developed at the APL, known as the TIE Advanced v1, made its public debut during the Empire Day parade held in Capital City in the year 5 BBY.