An ADM is an Agency Debit Memo.. goes back a long way, and I'm no travel agent, but is a mechanism for the airlines to charge back to the agent / whoever issued the ticket additional amounts due to fare rules not being kept to etc etc.

For example the IB mileage run LON-BCN-AGP when AmEx went to ticket came up with an ADM of £69, i.e. an additonal amount on to the fare for going via BCN. I assume Expedia have some deal with IB where they don't get charged the ADM or such like.

According to the rules the I class fares are only valid if all segments are flown, otherwise you are liable to the full fare for that segment. That's been the rule as long as I can remember but the few occasions I've not used part of a restricited CE I-class I've never had any comeback.

Be very bad news if BA start getting strict with the rules IMHO, they may think it'll drive full fare CE sales but for me I'll be moving down the back on most routes I suspect.