Originally Posted by zencat

What you're suggesting would seem to negate booking code "M" and "E" for all airlines. But they have different meanings for each airline. E.g. class K on UA is worth 100% of the mileage, but class K on LH is only worth 50%.

So suppose I want the search to be open to all airlines, but I want it to exclude the booking codes M and E of LH, but allow M and E for all other airlines. How would that be written?