Have you ever wondered why, when seated in First Class (I call it Business, oh well), you would sometimes see attendants taking orders from the first row and sometimes from the last row?
On American, this was called FEBO. Front Even Back Odd.
If your flight number was odd-numbered, meal order taking started at the back, if even-numbered, it began at the front.
With the merger and the messy route numbering system (same number on both directions, who came up with that?), we have a grand unveiling of a new system.
From September 1st onwards, this will start:
When an aircraft flight involves a change of time zones, take meal preferences:
Eastbound: from forward / front to aft /back
Westbound: from aft to forward
If the flight does not involve a change of any time zones, take meal preferences:
Southbound: from forward to aft
Northbound: from aft to forward
Because that's much simpler.