Q: by IIb7M i mean like if the song is in A, then Bbmaj7. how would be the correct way of writing it?
A: oh i see. where i am from it is all the reverse of that. bIImaj7. "flat 2 major 7." or bIIM7 although I prefer to use maj, just so it's extra clear not to be confused with minor. and i personally prefer to use minus sign - for minor. and even more personal is that i prefer to just not even use roman numerals because it's been a long time since rome. but that's just my preference. that being said it really doesn't matter as long as it us understood by whomever is reading it