As far as I know the "areas" are generally as follows:
Area 1 : North and South America
Area 2 : Europe, Middle East and Africa
Area 3 : Asia and South Pacific

For a paid ticket I know you can backtrack within areas, but not between areas, so the DXB-ATH backtrack is probably legit on a paid ticket. For an award ticket I'm pretty sure no backtracking is allowed, except to make connections.

That said, I booked a westbound SkyTeam RTW award and was able to get away with going AMS (stopover) - LIM (stopover) - MEX - JFK (stopover)
... even though Lima is a few degrees west of New York. So maybe they relax the restrictions sometimes.