Is there a US Embassy near you, or within reasonable travel distance?
You might be able to get help there. I'm completely baffled by your question, I haven't been able to find an appropriate answer.
US embassy is within reasonable travel distance. I called them, but they did not give me any answer.
I think this is very common case - every one who filed his I-129 should have entered something in that field. I just wonder what exactly I should write there.