What is the prime Una timeline, and when was it established?

Unbelievable. That’s the same combination I have on my luggage.

I seem to remember the official explanation being that they’re not that far apart, but that the holodeck can use perspective tricks to seamlessly make them seem that far apart. You could run away from someone in one direction and never hit the wall while things shrink and enlarge to make you seem far away from your companions.