Common acceptable practice is the use of 'from-to' fittings to eliminate the need for a box. Over the many years I have been in the trade, I have seen, used, made up many a transition from cable to raceway, etc.

To get to the core of your topic, the markings on conductors IMHO in a situation would not raise a question.

I seem to remember seeing markings on some #12 or 10 MC. It was stranded for sure. I'll reach out for the EC who is on that job to check. I'm not disputing what you say Reno, I just feel it is something that just gets by without ????




John