Horizontal integration facility

A horizontal integration facility (HIF) is an integration facility where missiles and rockets are assembled before launch.
HIF elsewhere.
Most Russian, Ukrainian and former Soviet launchers are integrated horizontally, including Dnepr, Proton, Rockot, Shtil' and Soyuz. The Electron launch vehicle is also integrated horizontally and European Ariane 6 would also use HIF to integrate its rocket stack.