Tony M Jan 22, 2017:

@ Asker I sympathize with your dilemma! The fact that they don't then go on to say anything about what they've put in the heading is really not helpful at all!
I strongly suspect, from the logic of things, that it might mean EITHER bookings where a passenger literally changes cabins (i.e. class) OR where they change plane — but without knowing what they are trying to say about it, it's hard to tell. Are they saying we cannot / must not do this, or it isn't possible to, or the software avoids problems... I can imagine that if, for example, a passenger gets left off one flight because it is over-booked, then of course this passenger might become a non-show for either an onward flight or a complete new journey. I think these are perhaps the sort of areas you might try exploring...

Clearly there is little point solving an over-booking problem by leaving a passenger behind on one flight if this is going to cause knock-on dead seats and even greater losses as part of their onward journey; these factors therefore need to be taken into account by any self-respecting computer program, even though the tendency would clearly be to consider each flight in isolation.