Re: What exactly is...
It could no doubt be configured to fufil any need. As one would expect gien the advanced computers they have any station could be configured to do anything. So in theory tacitcal and ops could switch locations. Depending on how a particualr CO wanted it.
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.