Don't know what a donex is, will search.
It is simply a Oneworld RTW business class airfare. It books into the dicount D bucket of Business Class fares.
So, D bucket must be available on a sector for it to be bookable into the RTW fare. Because it is a discounted bucket, it may not always be available.
However, D bucket does earn full J SCs and points.
And, as I said, x simply indicates the number of continental zones.
Here's the link from the QF website:
Enjoy great savings on your Round the World flights.
The OW website:
RTW Flights: Round The World Airline Tickets - RTW
There are rules, but once you get your head around them, they are not too complicated.
Basically (OneWorld Explorer):
16 flight sectors max
One way between continental zones; any direction within
4 flight sectors in each continental zone, except for North America, where it is 6
Only one full coast-to-coast trans-continental flight allowed in each continental zone.
Caveat: they were the rules in my day before covid stuffed up my ongoing plans. They may be different now.