which carrier did you book through? Does it make a difference for availability?

Thank you, anabolism, for the above. I have learnt so much thru this post from you and ernestnywang 👍🏼👍🏼 Indeed, I have checked EF for married segment, and the 2 flights CX and JL for the changed date showed no business seat inventory. However, when I just queried individual flights there was some D inventory.

Thank you again, ernestnywang for persisting with my question re seat selection on AS codeshare flight with JL. My OTH said I should stop wasting time as it is only 4 hours flight so we should just accept the assigned seats - still better sitting in the back of the bus! However, I am not a defeatist, and will contact the TA - hinting to him what you have suggested, ie trying if SSR code might work. He may think I am too demanding and tell me to go away. I can see the seats originally selected by the TA (before I changed the 2 flight dates) are still available on EF map.

If I were your TA I would have proactively tried my best to get the seats for you (if possible, of course), but then I don't do this for a living.

I could have been clearer, this was with the AA RTW desk like all my RTWs after prior issues with CX and QF booking via the online tool. I feel that JAL and AA really don't get on for availability, but I'm not willing to book via JAL, or use a travel agent so I'm a bit stuck with this. I just like the flexibility of AA and their deep knowledge of the fare rules. This has removed my willingness to book AONEx tickets though.

From what I can tell, it seems that both AA and JL honor GDS type of fare restrictions, that is, if the operating carrier has restricted 'A' or 'D' or 'L' availability based on xONEx fare, both AA and JL will see the unavailability.

A segment is first booked before it can possibly be attached to a ticket, and only the ticket has a fare basis. Technology is evolving, and maybe there are things I don't know, but it doesn't make sense to me how such restriction can be put in place. You create the PNR first before pricing it as xONEx or something else. How can the computer know which fare you will price the PNR in advance at the availability display stage. There are also cases (though very rare I imagine) where people change an xONEx to a regular round-trip or one-way itinerary or vice versa.

I believe it's all just a combination of Married Segment Control (MSC), Point of Sale (PoS), and Point of Commencement (PoC).

Excellent questions, which unfortunately I don't have the knowledge to answer. When I've booked RTWs, the booking agent sets it up as an RTW. The AA RTW desk first puts in some basic information which identifies it as a RTW fare. JL agents take a lot of information down by hand first, then create the record. (I can't recall the process when QR or MH booked them.) It's possible that in some cases the airline has a front-end that establishes the type of fare first, and in others the segments would initially show confirmed but after type of fare is established they'd come back unconfirmed. I'd be very interested in knowing more about the process.

Are A, D, and L fares used for anything else by OneWorld carriers?

Me too. I've had something similar to what you describe happen when trying to change a JL flight. The AA RTW desk could see availability for the new flight (including within my existing PNR) but it always came back unconfirmed once they tried to actually book it. Of course, getting the flight confirmed outside of the existing DONE booking was no issue at all. (it was definitely not a married segment issue) They even tried calling JL (I think via the oneworld liaison desk) who refused to release it for a DONE, so I think the fare basis does matter for availability nowadays.

I've heard from the BA forum that availability for changes/existing bookings can differ from what you see for a new booking too. Honestly I feel like it's getting harder and harder to know what's actually available to you!

Yes, BA uses A for discounted first class and D for discounted business (more discounted than C, but still way better availability than I). You can definitely buy regular cash A/D fares or even use a gold upgrade voucher to book a redemption flight using commercial A inventory. So A and D are not RTW specific by any means on BA.

Finnair uses D for discounted business too, not sure about the other carriers or L.

Last week I flew on a D/I fare with AA, just a regular roundtrip to Europe.
D fare on the outbound because I had to make a last minute change to routing.

Yes, these are general revenue inventory codes, generally used for discount first, business, and coach (respectively). The reason they were chosen for xONEx fares, I believe, is because they are used for discount inventory and hence are not "last seat" inventory. This was long before it became possible to restrict inventory by type of fare. Similarly for an IONEx, which books into 'I', as 'I' is a discount business class inventory that's more discounted and less available than 'D'.

Some carriers (e.g., AA) also use 'A' for first class upgrade inventory. When looking for 'A' availability, it's possible to query for revenue 'A' or upgrade 'A' as they are different.

I definitely understand you are report your true observations. I don't doubt that. However, I am not convinced the reasons are what you believe to be.

I would have done the same simply because, once the segments are booked, you only have a limited time to save the PNR. In Sabre, the status code is first Sell Segment (SS), then one has to End Transaction (ET) before SS gets changed to Holding Confirmed (HK) during the initial creation of the PNR. Amadeus behaves similarly though use DK instead of SS. If anyone attempts to enter most of the information only after the segments are booked, one risks losing the SS status of the segments booked. I don't believe anything is entered at the "fare" level during the initial creation of the PNR, except an "OSI YY OW RTW" or similar line to indicate that all airlines should set the Ticket Time Limit (TKTL) consistent with the xONEx rules. The AA RTW desk creates the PNR and then sends it to the Tariff Desk for pricing after. If the "OSI YY OW RTW" can result in change in availability display (I highly doubt), one can simply just enter that single line after all the segments are booked. If there are airline internal policies that say any agent booking RTW needs to enter such line first or otherwise enter information that tells the availability display system that this is an RTW, or that the AA RTW desk sees more limited availability because of Point of Sale (PoS) restruction, wouldn't the airlines give TAs more of an advantage for seeing expanded availability?

I really don't think so. You can lose a confirmed segment if you didn't save (ET) the PNR in time, but once the status code has changed to HK, you don't lose it after merely pricing it. You only lose an HK segment if you didn't issue the ticket before TKTL or if the flight itself got cancelled or down-gauged.

There can sometimes be availability discrepancies, though your cases sound to me like the initial availability display did not correctly reflect the Point of Commencement (PoC).

Can we possibly see if JAXBA has any comments? Maybe a new technology is being implemented that I do not know of?

I would very much like to better understand what has changed. A few years ago, availability was consistent for regular fares and RTWs. In some cases there were point of sale differences, but those affected all types of bookings. Now, it is clear that RTWs have reduced availability compared to regular records. With both AA and JL, a flight have be D9 in Sabre or Amadeus in an ordinary record but D0 for an RTW record. The same flight for the same date shows the same restriction with AA (Sabre) and JL (Amadeus). I mention those two airlines because I haven't asked any others. I did ask a friend who books his own (non-RTW) tickets in Sabre and he was able to book the flight but told me if he proceeded it would likely come back unconfirmed later.

I know there are other reasons a confirmed segment can change to unconfirmed, e.g., if the operating carrier finds a flight for the same passenger in a different record that it believes conflicts. A corporate TA told me there are things one can do to work around married segments for UA but those same things would cause the segments to change to unconfirmed with AA flights.