From Bulbapedia, the community-driven Pokémon encyclopedia.
Each location Pokémon Colosseum and Pokémon XD: Gale of Darkness has its own identification number used internally by the game, mostly to display where a Pokémon was caught. They are enumerated here, in order.
As none of the locations in Orre correspond to locations in Kanto or Hoenn, Pokémon traded to any of the Generation III handheld games will display "met in a trade" as their captured location. When transferred to Generation IV, Pokémon will, like with Pokémon caught in the handheld games, use the game identifier to mark the Pokémon as being from a "Distant land", rather than "Orre".
If a Pokémon caught in Pokémon XD is traded to Colosseum, it will most likely display the captured location as "Mt. Battle", even if it was captured in a location that appears in Colosseum because most areas where pokémon are caught in the former, correspond to Mt. Battle in the later. Likewise, a Colosseum Pokémon will most probably be identified in XD as being from a "Distant land", even though it was captured in the same region. This is because both games share the exact same list of location indexes. In the following table, locations not listed will display "met in a distant land" on both games.