In a performance commentary, octave designations are given in superscript form, e.g. "the accented d(superscript)2" or "the grace-note c#(superscript)2". How should I handle these in this literary text? Thanks for your help!
You can handle this in either of two ways. Since the note is given as a letter, you can use the FORMATS superscript device. If you think it would be clearer to the reader, you can use the music prefix, switch to music notation, and show the note with its appropriate octave mark. I'd favor the latter, because it's about music, not algebra.