Originally Posted by number_6
The xONE3 fares are not limited to 17 segments, you just have to pay extra to fly the next 3! You can buy 2 extra segments in each continent other than your origin; this may or may not be a cost-effective strategy. The extra segments can be bought in D or L instead of A.
But note that some airlines insist that the "extra" segments in a region be the chronologically last two, while others allow you to designate any of your segments as the "extras".
Applied to your disadvantage that can mean (for a random example) that if your 5-segment AONEx SWP journey ends BNE-SYD-PER and you were thinking of making the BNE-SYD a coach-class "extra" segment, you're out of luck - QF appears to have trained their agents to insist that SYD-PER be the "extra" one. BA and AA seem to allow the pax to designate (although it may be the luck of the rtw desk/rate desk agent draw). Not sure what CX does - I've got a CX-issued ONE in hand and will have to take a look to see what they did to me.