Welcome to FT! If you have your eticket receipt you should be able to see the fare basis in the "Receipt Information" section. It will look something like this: "LAX DL X/ATL DL BOS115.35TA10X3SJ /-BOS DL X/MSP DL LAX91.16TA14NI/WN1B USD206.51END" The string of characters in bold is the fare basis code for that segment with the first letter signifying the booking class. Also, on your DL boarding pass (if you have one for this trip) the fare basis code is printed under you SkyMiles number.