ac12
Mu-43 Legend
I think you are right about "EM1I" looking like a typo. But I've been using EM5III and EM10III (and others do too, I think, perhaps sometimes with a hyphen) and it seems to be pretty well-understood. So I guess it's really just when talking about the EM1 models where we need to be careful about this, huh. Since this is totally off-topic, I guess I should stop beating it to death now...
I sometimes get confused when I am reading. That is why I use EM1-mk1, to make it very clear which model I am referring to. The EM1-mk1 is especially confusing, since someone could be talking about EM1 in general or the EM1-mk1 specifically.