I don't believe that MM stations can be worked in ARRL DX, at least
from the DX end. A DX station must receive a valid state or province
for the QSO to count. A MM station could send its power as an exchange
to a domestic station. The usage of "geographic units" (countries or
states/provinces) argues against maritime mobile QSOs in ARRL DX.
CQWW is somewhat of a different situation, where the exchange is a
zone. Every station on the planet has a zone, so this would appear to
naturally include MM stations. However, even this logic breaks down
for a QSO with the MIR space station.
The ARRL 10M and CQ 160M contest specifically recognize MM stations
with region multipliers. Entering "RR1" or whatever in the QTH field
overrides the country determination which makes this work.
I think W4OX's need is for logging his non-contest QSOs in which case
something akin to what I proposed (/M & /MM are decoded to their mobile
status) is needed.
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