To clarify, if you are changing an airport between a transit (X) and a stopover (O), that is clearly a re-routing and the 125USD fee kicks in.

Here is a data point. For my DONEx ticket issued by CX, I flew only the first flight (into HKG) for a less than 24 hour transit. There at the CX Wing F lounge, I requested for change of dates only, affecting all remaining 15 segments. CX agent did it while I was relaxing in the lounge. It took about 50 minutes. No charge.

Just for clarification, I added the parenthetical note "(regardless of being a stop versus a connection)" only because [MENTION=10043362]scotbus7[/MENTION] wrote "changing any of the actual stops" and I wanted to clarify that changing the ticketed points triggers the charge, even if a point being changed is a connection and not a stop. As for changing an airport from a stop to a connection or vice versa, I don't personally know if it is supposed to trigger the re-route or not and I would appreciate if someone could point me to an authoritative source for the definition of "ticketed points." I see the logic in what [MENTION=77686]ernestnywang[/MENTION] writes, because the fare calculation always specifies X vs O so it would make sense that changing this is a reroute, but since I don't know the precise definition of "ticketed points" I am not sure. I've had airline agents make such changes without charging me the $125 fee, but that could have just been agent error. When making RTW bookings with dummy dates that I intent to change, I always make sure that any place I want to stop has more than 24 hours between flights, and any place I want to connect has under 24 hours, because I want to be safe.

If you are changing from X to O, in the vast majority of cases additional taxes need to be collected, and the only way to do this is to re-issue. If an agent does not charge you the additional tax you owe, that's a clear error.

If you are changing from O to X, at the airline's / agent's discretion, it may be possible to leave it as an O even though it is under 24 hours. This is doable.

Due to the low base fare on my RTW fare, I ticket as many stops as possible due to not having to deal with married sector logic when I do date change.

Taxes have always been recalculated when I have made changes between X and O, or changing carriers. It's just the $125 fee that I was addressing.

In my experience, a change from a transit to a stopover requires the ticket to be reissued (which will result in the fee). As others have noted, on a very rare occasion I have had an airline not charge the reissue fee.

Married segment kicks in as long as the time between flights is less than 24 hours. It is something on the reservation end and has nothing to do with whether the ticket says O or X.

I suppose it is possible to have a recalculation of taxes, and thus a mandotory re-issue, without a change in routing, so it is not consiered a re-routing. That being said, if O/X is changed, this is definitely a re-routing, and per the rule 125USD should be charged. Perhaps some agents might have (mistakenly) waived it for you. Count yourself lucky then.

This has been discussed quite a bit before, and I believe the consensus is that a ticket reissue is not supposed to trigger the $125 reroute fee. Some airlines, such as AA, never revalidate, they always reissue for any change, and they only charged me the $125 fee when I've changed the airports that were touched. As it happens, I am in a situation now where I have an agency-issued xONEx and the agency tells me they are prohibited from revalidating, and their interpretation of the rules is that any reissue does trigger the $125 fee.

Yes, but I think pbd456's point is that if they don't know dates when they first ticket then they make sure that all the dummy flights have stopovers at intermediate points unless they are 100% certain that it will be a transit. That way once they start the ticket and then need to adjust individual flights there is never a need to reissue the ticket even if what was originally ticketed as a stopover ends being a transit (they just forgo any tax refund, but save the reissue fee), and they hope that just rebooking a segment subsequently doesn't trigger married-segment lunacy.

That's certainly the way I always used to do it, but my experience is rather dated now (this whole "married segment" thing is a rather recent phenomenon)

I used sloppy wording, sorry. By "taxes" I meant "taxes and airline-imposed fees (e.g., YR/YQ)". Changing the marketing carrier on a flight can change the airline-imposed fees. Some airlines like to recalculate the taxes for any change (perhaps in case the taxes changed?) which because of exchange rate fluctuations can be a different amount than when last ticketed.

The fact that what you said doesn't work is exactly what I am saying. Even if the ticketed point remains an O, if you are booking two flights and the time in between is less than 24 hours, the "married segment lunacy" is triggered. One must understand that the whole "married segment control" concept only occurs at the reservation end and has nothing to do with how the ticket routing was written.

I understood what you mean; YR/YQ is the only thing that could be different. There are some very rare occasions where an airport's tax is raised and requires airline to collect the new amount if the ticket is ever reissued, but other than that, if no ticketed points and O/X are changed, taxes other than YR/YQ should not be any different. Exchange rate fluctuations would only be considered if this is a re-issue before dep. For re-issue after dep. (after 1st segment is used), one is always supposed to use the exchange rate on the original date of issue.

In Europe at least, many airport fees and government taxes are contingent on whether it is O or X. And indeed UK's APD can vary on time of day between arrival and departure if domestic flights are involved.