I recent bought a ZX-m and have been enjoying it BTW. AFAIK this camera when it was sold i the USA was known as the ZX-m while when sold other places was the MZ-m. Apparently that was the only difference as the cameras are identical.
Blackcloudbrew is right!
When sold in the US, the model was ZX (ZX-5n, ZX-7,etc..) but on other parts it is an MZ (MZ-5n, MZ-7, etc..)
You can further see the differences of different models at our camera reviews/database section.
There seems to be a problem with it at the moment since it is missing from our forum including the lens reviews/database from our site.
You can access these on a later date when everything, I guess, is up and running again.