Kiwi - thanks for your response. Anyone else have actual experience w/ getting charged? How would they go about charging me?? (The only way I can think is on the credit card I used to purchase the XoneX in the first place). Thanks.

Yes, or if you booked through a travel agent the ticketing airline could issue a debit memo to the agent who would then chase you for the costs you've incurred them.

But in practice, despite this question being asked here many times over several years there has not been a single report of it happening that I can recall.

I think you would be hard pressed to show us a post from the past few years of someone canceling an xONEx mid-trip, without invoking the medical or death in family exception. Yes, the question has been asked many times but there is also little, if any, anecdotal evidence on people canceling xONEx mid-trip and there success or failure. I would venture a guess that the number of posts about people being charged for canceling an xONEx mid-trip correlates pretty well to the number of posts about people canceling a xONEx mid-trip in general. Missing the last "yet to be booked" segment of an open dated paper ticket is one thing, but missing a few remaining flights of a xONEx e-ticket is another. I don't believe I have seen one post on this subject. BTW, did the OP indicate whether this was an electronic or paper ticket?

Note to OP: please let us know how things work out so we will have the start of our anecdotal evidence in regard to xONEx tickets being canceled mid-trip.

Fair enough - I have failed to take the last one or two segments of a paper-ticketed A/DONEx ticket a few times without any problem, including (as mentioned) getting off a LHR-MNL at HKG, and I'm pretty sure that those ticket coupons have had reservations associated with them on some occasions. In the early years these were done via a TA who never had any comeback from the airlines either. More lately direct with airlines and their GSAa.