You are factually incorrect in the very first statement. “Gulag” means “главное управление исправительно-трудовых лагерей” and is a name of a state agency directly operating a network of concentration/forced labor camps. Each of the camps had their name, control and command structures and operated under direct oversight of some best Stalin’s chaps.
Also, it wasn’t just ‘prison’. Each of them was a concentration camp for politically it otherwise unsound elements, that provided Stalin with supply of free slave labor.
You didn’t need to direct me anywhere to accept that you made a clear factual mistake.