That is an excellent question. I am inclined to follow Nemeth Code closely for the construction of the note indicator, since the Nemeth Code does provide specific direction for formation and placement of a note indicator. However, I am not certain that is what we should do. Please let me check with others and get back to you.
My official recommendation is to follow BRAILLE FORMATS 2016 for note indicators.
Although the Nemeth Code does provide specific rules for note indicators, they are not mathematical/technical, and the Nemeth rules on notes do not serve a practical purpose in a UEB environment, so let's follow the Formats rules, barring unforeseen circumstances.