Codesharing is pure marketing. It gives many of the same beneifits of a merger (access to consumer bases, networks, etc.) without the costs / loss of identity / etc.
There's different types of codesharing...
- e.g. NW/CO - the carrier that operates the flight gets the revenue from the coupon (from whatever formula they use)
- e.g. NW/KL - NW/KL split all transatlantic revenues
- e.g. AA/MU - AA purchases a block of seats on MU's LAX-PEK flights
[Edited 2004-01-13 06:00:24]