Originally Posted by Adam Smith

/ alliance star-alliance. A helpful guide is here.

The codes that will be useful to you really depend on what you want to do.

Last year I wanted to fly YYC-LON (stop)-ZRH; ATH-YYC. I wanted to do it on *A and I wanted to fly home on FRA-YVR so I could do 747 upper deck.

So I searched multi-city, YYC-LHR; LCY-ZRH and had to do ATH-FRA and FRA-YYC separately to get the FRA-YVR-YYC I wanted in the end.

I used the / alliance star-alliance filter to only get *A flights.

I used the N filter to only get non-stops on YYC-LHR, LCY-ZRH and ATH-FRA flights. I filtered by connecting airport to get the connection through YVR on the way home.

And so on...

But you may have completely different needs. So if the guide still isn't clear, feel free to post questions and I'm sure people here will try to help (I will).