Unfortunately each airline uses its own bucket codes.

I think F (paid first class) and Y (full fare coach) are the only ones that are universal. And even those might not be.

You should be able to do a search on Flyertalk for fare classes for LH and get a list.

My guess is that the ones before Y are for first class fares, the ones after Y are different levels of discounted seats. The different buckets may indicate things like upgradeable fares, first class seats available through upgrades, etc. But I don't know the details for LH. I'm sure someone with more info will post it though.