Originally Posted by
KARFA
The bp should show the operating carrier flight number so for your example AA101. If you booked it under one of those codeshare it may reference that, so if might show as "AA101 booked as BA1516"
Just as a very minor note: exactly what is shown depends on the carrier printing the BP. In the case of AA-operated flights booked as a partner codeshare, with a BP printed by AA, the BP will show the AA flight and then somewhat smaller "sold as XXNNNN"