Is every fare code that starts with the letter B considered a B class ticket? I see both a refundable and a non-refundable B fare on one particular route and, as you can imagine, the non-refundable B fare is much less expensive.

My concern is that I need to book a B fare as part of the targeted offer to re-qualify for 1K. The e-mail says I need to book a "full-fare economy (Y, B) class." I'd love to book the non-refundable B class if it would qualify, although it hardly seems "full fare."