This question came up as I was doing some research for a colleague who picked up a mileage run ticket as per the MR forum. The restrictions on many international B fares are few and so where the fare conditions themselves don't prohibit changing the outbound leg one has to resort to the conditions of carriage regarding whether a change is allowable and whether such a change will trigger a fare recalculation. From the conditions of carriage:

"EXCEPTION 1:
No increase will be collected in cases where the ticket
date of:
• a change in the fare level,
• a change in conditions governing the fare,
• a cancellation of the fare itself.
provided that:
1) The originating flight coupon of the ticket was issued
effect on the date of ticket issuance (i.e. no open
2) The originating flight coupon of the ticket is not voluntarily
request after a fare increase has taken effect."

So, any fare increase is *not* collected if you don't change the originating flight coupon and it isn't an "open" ticket. Now to me, the originating flight coupon is the first flight coupon of the ticket because that is the coupon one uses to leave the origin, but some pax have been told that the originating flight coupon refers to either their entire outbound leg or the transoceanic flight coupon on the outbound leg or leg to first stopover. These definitions are both BS in my opinion.

Is it possible that Delta's agents are simply confused by the fact that sometimes the CoC rule catches people on their trans-oceanic segment but sometimes it should actually refer to a connecting flight en route to the international gateway?

I don't think a definition other than "the first flight coupon of the ticket" can be defended judging by the use IATA make of the "coupon" terminology. So what do the seasoned Delta travellers make of this rule?