I just happened to pull up the fare rules in EF for a DONE5 ex-NRT on JL (likely these are identical for all xONEx, of course), and noticed a few things:
CHANGES
BEFORE DEPARTURE
CHARGE USD 125.00 FOR REISSUE.
...
BEFORE DEPARTURE
CHANGES PERMITTED FOR REVALIDATION.
NOTE - TEXT BELOW NOT VALIDATED FOR AUTOPRICING.
LOCAL SERVICE FEES MAY APPLY ON REBOOKING
-------------------------------------------------
REBOOKING PRIOR TO DEPARTURE
CHANGES ARE PERMITTED PROVIDED TICKETED POINTS
REMAIN THE SAME. IF THE DATE IF THE FIRST FLIGHT
COUPON IS BEING CHANGED AND THE FARE HAS
INCREASED SINCE TICKET ISSUANCE THE DIFFERENCE
BETWEEN THE OLD AND NEW FARE BE CHARGED.
IF THE FARE LEVEL HAS DECREASED SINCE TICKET
ISSUANCE NO REFUND WILL APPLY.
...
AFTER DEPARTURE
CHARGE USD 125.00 FOR NO-SHOW/REISSUE.
...
AFTER DEPARTURE
A. CHANGES TO TICKETED POINTS PERMITTED AT A
CHARGE OF USD125.00 PER TRANSACTION.
B. NO SHOW REQUIRES REBOOKING AT A CHARGE OF USD
125.00.
C. IF THE REROUTING RESULTS IN A CHANGE TO THE
TOTAL TICKETED MILES THE TICKET SHALL BE
RECALCULATED.
...
AFTER DEPARTURE
CHANGES PERMITTED FOR REVALIDATION.
NOTE - TEXT BELOW NOT VALIDATED FOR AUTOPRICING.
LOCAL SERVICE FEES MAY APPLY ON REBOOKING
-------------------------------------------------
AFTER DEPARTURE
CHANGES ARE PERMITTED PROVIDED TICKETED POINTS
REMAIN THE SAME.
To my reading, this sounds like any ticket reissue, even for a change to carrier/date/time, costs $125. I realize that many airlines do a revalidation for such changes, but some (such as AA) reissue for everything. Also, in a case where D isn't immediately available on a flight but becomes available later, my understanding is that requires a reissue, as cabin changes can't be handled with a revalidation. It says that changes "are permitted provided ticketed points remain the same," but "are permitted" doesn't mean "for free."
Also, what does it mean that "if the rerouting results in a change to the total ticketed miles the ticket shall be recalculated?"