Thanks for the hints.

Actually "www.virtuallythere.com" worked to see a e-Ticket-Receipt - and there I see these Fare basis codes.

How can I be sure, to decode them - is it true all the time and for all Airlines it's the first letter?

For my next travel I see:
For the Swiss-Flights: LSWISS --> So that's booking-class L?
For the Austrian-Flights: TNN21G2S --> So that would be booking-class T?

Is this really sure?
I have seen comments like this in this forum, but not with these codes and have found nowhere else in the internet similar information.


Thanks again