Now if your itinerary actually starts in North America, it opens up an interesting possibility. How about somebody based in Miami doing this:

The new rule is simpler, but also makes invalid an itinerary that includes South Africa and transits Europe/Middle East twice. E.g., JNB-DOH-rtw-DOH-JNB.

????
Rule says
Rule doesn't say
IMHO,
JNB-DOH-rtw-DOH-JNB isn't to/from Europe in both directions.

Furthermore,
is vague.

In previous rule, there is a description:
Europe/Middle East - Africa - Europe/Middle East
So, we may understand 'both direction'.
However, new rule doesn't have such description.
So, what is 'both direction' ?

I hope you're right. Since Europe/Middle East is lumped together, I read it as prohibited, but would love to be wrong.

In the rule, clearly distinguished.
A rule maker could say like
But, the rule maker doesn't.
So, in this current rule, an itinerary that has two intercontinental departures/arrivals and includes Mauritius/South Africa may exist.
What is such an itinerary ?

Would it be correct to assume that it is now possible to enter NA, use say 3 of the 6 NA segments, pass through SA, and then enter NA to use the remaining 3 NA segments?
That is how I read the rule and wonder if anyone can confirm that this seems a reasonable interpretation?
If so, it surely adds a great deal of flexibility to the NA segment and is most welcome from that standpoint.

Your reading makes sense, so I'm happy to agree. Ex-South Africa isn't the bargain that it used to be, but still isn't bad, so something such as JNB-DOH-SYD-NRT-JFK-LAX-LHR-JNB would be valid. Or possibly MPM-DOH- ... -JNB.

I'm curious whether the itinerary (for which QF agreed to use the new fare rules) was ticketed prior to Aug 1, 2017.

I'm also curious whether there is anything explicit in a typical xONEx fare rule that specifies that future rule clarifications/changes must be ignored or refused at the time of any future ticket reissue(s).

I have an xONEx ticket purchased last year (before Dec. 1), with the first flight next month, and I'm wondering whether rule changes that have occurred since purchase will be permitted or refused when, after the first flight, I submit requests for routing changes. The two that most impact me are 1. the then-existing limitation on U.K - Middle East flights (NOT MORE THAN 2 OF WHICH MAY BE BETWEEN THE UK AND ALBANIA/ALGERIA/BULGARIA/CROATIA/CYPRUS/GREECE/LIBYA/ISRAEL/MIDDLE EAST/MOROCCO/ROMANIA/RUSSIA WEST OF THE URALS/TUNISIA/TURKEY/UKRAINE); and 2. the ability to take a stopover in N. America, then visit S. America, and then return to N. America with a stopover (and not just a transit). I know that historically there were some limitations on applying newer rules to these tickets, but I'm wondering whether that was a contractual issue or more a tradition followed by certain telephone CS agents (i.e. perhaps overcome today by HUACA).

Insights very much appreciated.;)

This is the standard IATA rule for doing a ticket change. (See for instance the IATA Ticketing Handbook, changes chapter.)

For a whole unflown ticket, the old ticket is exchanged for a new one. Essentially, the value of the old ticket is used as a credit towards a wholly new ticket issued according to the situation today. (There is an exception if the first fare component is not changed.)

For a partially flown ticket, the old ticket is reissued, and all historical fares (and fare rules), are taken from the date of original issue. (It needs to have been theoretically possible to have issued the new itinerary on the original issue date.)

RTW or xONEx fares are not "special" in this regard. If the airline treats a rule change as a "clarification" as you put it then they may be willing to use the new wording. But if it really is a rule change, then strictly speaking they should use the old rules for a reissue. Of course you may be able to get away with it because these fares have a large amount of manual process in them.

While that might be true in theory, things seem to work differently in application. For example, in the past there hasn't been problems adding flights on a new carrier that wasn't a oneworld member before the ticket was issued. Of course oneworld hasn't added a new carrier in years, but they have changed the routing exceptions fairly frequently and I haven't seen anyone report being denied a change because they were being held to "old rules." When I purchased my exMPM DONE5 last year AA stated I couldn't route back through Europe to finish on Africa, but the rules changed and they allowed me to change my routing.

I think, like you said, these tickets are so complicated that no one takes the time to go back and study all the iterations of the rules in effect at the time of ticketing.

the link gives the old version of the rule
-------------
Only one intercontinental departure and one intercontinental arrival permitted in each continent except as
follows:
1. Two permitted in North America when one is a transfer without stopover.
2. Two permitted in Asia when one is a transfer without stopover or on direct single plane service between the
Southwest Pacific and Europe/Middle East.
3. Two permitted in Europe/Middle East:
-------
is there a pdf file of the new version online? I can see it in expertflyer but it is very messy to decode and show it to agent when challenged.

Here is the link to the PDF version that's currently on the oneworld site: https://www.oneworld.com/documents/1...9-d346ec820edf.

this is 4e in the rule via clicking the link above...

----

(e) Only one intercontinental departure and one intercontinental arrival permitted in each continent except as
follows:
1. Two permitted in North America when one is a transfer without stopover.
2. Two permitted in Asia when one is a transfer without stopover or on direct single plane service between the
Southwest Pacific and Europe/Middle East.
3. Two permitted in Europe/Middle East:

It appears that the rule change we spotted on 15-August has been reversed.

The version now on the web site has the above wording as posted by pbd456, which is the wording that had been there for some time.

Looking at the document properties for the now current version and the version that was there on 15-August (I took a copy):
15-Aug version was created on 1-Aug-17 at 11:47am
Current version was modified on 1-Aug-17 at 3:51pm

However, looking at the GDS version of the rules in ExpertFlyer, it reflects the rules at they were on 15-Aug, though it is not an exact match (see the 15-Aug wording in post #461)

what is the actual rule? it seems GDS should be the authority?