Long before Traveller 4 and it Year Zero Mileau was published. I decided to define how the Third Imperium worked in my game. Based on the few canonical hints I came up with the Articles of the Incorporation of the Third Imperium.
You can download them here.
Years later when I read through the Mileau Zero stuff I was pleased at how close I hit the mark. The big difference is that I was influenced by H Beam Piper vision of Empire and had the clause that all Nuclear Weapons are to be surrendered to the Imperium.