[douglas]

All of the following statements have been thoroughly tested. Please do not dispute them without testing them yourself. They also all refer to "ship ID". A ship's ID number is a unique identifier assigned to ships when they are built. It is not visible to the player. The first available ID is the one assigned. When a ship is destroyed, its ID becomes available again.

The order of repairing ships is completely independent from the repair priorities list. Ships are repaired in order by ID number. Repair priorities only affects the order of components repaired within the ship.

Within each day in a turn's movement, ships move in order by ID number. This matters for certain stellar manipulations, seek after orders, and minesweeping. Fleets move all at once when their lowest-ID ship moves.

Stellar manipulation: Whether trying to open a warp point and go through it at exactly the same time works or not depends on whether the warp opener has a lower ID than the moving ship. Also, destroying and recreating a planet in one turn with two different ships requires that the create order be executed either on a later day or on the same day by a ship with a higher ID.

Seek after: Particularly important when all ships involved have the same speed. If a ship with ID 1 is seeking a ship with ID 2, both moving at the same speed, 1 will seek 2's location at the start of the day, and then 2 will get to move away. In this situation, 1 must either get very lucky or the player must deliberately and correctly anticipate 2's movement in order to catch 2. Going the other way, 2 will have a much easier time seeking 1, as 2 will seek after 1's after-movement location.

Minesweeping: Minesweeping, unlike combat, is calculated after each individual ship movement rather than at the end of the day. This means that a minesweeper can only protect a fleet that it's not in if the minesweeper (or the minesweeper's fleet's lowest-ID ship) has a lower ID than any ship in the fleet. This is rarely important, but there have been occasions when I wanted to attack RIGHT NOW and my fleet didn't have a minesweeper, but I did have a minesweeper the fleet could meet up with partway through the turn. I also occasionally have large forces split into multiple fleets travelling together so that I can split the force up without losing the fleet training bonus.

Now for a way to make all this information actually useful: Ships are sorted in the fleet transfer screen by ID number, lowest ID at the top. This sort order is in effect both in the list of ships not in fleets and within each fleet. The order of the fleets is by fleet ID, which is used for nothing else that I can tell, except the order fleets are displayed in the ships screen (F6). The order ships are gone through by the "Next ship" operation, typically accessed by the space bar hotkey, is also by ship ID. Unfortunately, this order is cyclical and your current position in it appears to be stored in the savegame, even through turn execution. Of course, you could try building an escort on turn 1 specifically to keep it around forever as your known lowest-ID ship, but this isn't guaranteed to work perfectly unless you're player 1 - anything players before you build on turn one will have a lower ID, which could possibly be freed later and taken up by another one of your ships.