A couple of Combat Question

[Zoompet]

Originally posted by Q:
Usually the ships that were already in the sector are in the middle of the combat map and the ships that enter the sector and attack are on the same side of the combat map as the side where they came from in the system map. If the incoming ships warp, they are in the middle of the map too and things get nasty. And if you have very large fleets, the ships may start close to each other even outside the warp point situation.
In one of the Last patches it was changed that the defender always should get the first movement/shot and this you can't change.

How does the game know who the defender is?