According to this, LOGic is not wrong per se -- the prefix can be Antarctica, or just a special-event station. So there is really no way to know.
http://en.wikipedia.org/...all_signs_of_Antarctica
Sure, you can delete the line, and it will fall thru to just 8J on the main Japan entry. I will do that to mine, and will just have to handle Antarctica on a call-by-call basis, or not worry about it.
A tip for testing what would happen if you remove an entry. Change 8J1 to 8J1ZZZZ, making it ineffective. Now enter your 8J1MTD call and see if you like the results. I need to add an IGNORE flag to the table tho.
Tnx & 73,
Dennis WN4AZY