Third and last, even when dealing with chemical notation that requires grade one indication past the 3rd cell in an expression, a transcriber should use a grade one word indicator instead of a grade one symbol indicator.

That’s what it says in #5 in BANA’s “Provisional Guidance for Transcribing Mathematics in UEB.”

Unless a math expression can be correctly represented with only a grade 1 symbol indicator in the first three cells or before a single letter standing alone anywhere in the expression, begin the expression with a grade 1 word indicator (or a passage indicator if the expression includes spaces).

[Will the final (i.e., not provisional) version of BANA guidance say the same thing? I believe it will say something different. But, for now, we should follow what is published.]