I hope some of you frequent flier gurus out there can help me. I have to book a PHL-MAD round trip. I can get a ticket at almost half-price (vs USAIR.com) at Vayama.com but Vayama can't tell me for sure if this fare is eligible to accrue US Frequent Flier miles. All they know is that the booking class for the ticket is "S". They suggested I call USAir to ask them if "S" class fares are OK for FF miles. I called USAir and they told me that knowing the booking class is not enough, and I have to talk to Vayama to find out whether this ticket is "bulk" or not, and if it is "bulk" no FF miles can be collected. Vayama's full booking code is SLXCN90, but USAir has no idea what this code is - it's not in their system. Vayama can't (or won't) tell me if this fare is "bulk". Why is this so difficult? Is there a web site somewhere which lists booking classes with their eligibility for FF miles? TIA for your responses.