Re: The prefix number
Shame they forgot about it most of the time. We have plenty of episodes where one starfleet ship is pursuing another and using the prefix code would end the chase quickly. Such as in DSN's "Past Prologue".
On the continent of wild endeavour in the mountains of solace and solitude there stood the citadel of the time lords, the oldest and most mighty race in the universe looking down on the galaxies below sworn never to interfere only to watch.