The Manual of Galactic Defense Orders was a book which contained the executive orders which could have been implemented to defend the galaxy from attack. At the time of its writing, in the late 8th century ABY, it was a closely-guarded secret, only the Supreme Chancellor and his aides had copies of it. Most of the galaxy (including the senate) had no idea that the GDOs (Galactic Defence Orders) even existed. The book was kept secret due to the fact that some of the orders had the ability to kill billions, and in the case of Order 101, trillions of citizens.