These should be fares sold exclusively via travel agents (BA ref), where there are a few fare tiers that offer refundability. There may be some marketing terms specific to the travel agent you are looking at, but officially they should be Select, Select Pro and Fully Flex.
If there are ways to check the GDS Brand Code this would help identifying which exact fare type they are referring to. In any case, these fare types don't correlate to the booking class itself - most booking class would have all the fare types filed.