Lufthansa Systems Blog - "codeshare" tag
Codeshare co-operations between airlines are reflected in the schedules with different Data Element Identifiers (DEI). The operating carrier labels its own operating flight wanted to be offered for a certain partner with a DEI 010 identifying the respective marketing flight.
As the airline industry is among one of the most competitive, airlines often enter into codeshare agreements - whereby partners mutually agree on common routes and flight numbers to generate additional revenue and improve operating margins.
You read in the news nearly every day that airlines agree on closer co-operation and announce new codeshares on certain routes and markets. Codeshare agreements are used to virtually extend your own operational network by adding new destinations. By connecting to your partner’s network and markets you will attract more of your partner’s passengers to your own flights.