There's that attachment! Thank you. My response to the attached question is below:
I agree with your treating the words "of" and "is" in phrases like "32% of $83" and "7.5% of [square shape] is 13.2" as technical material. In these instances, the words are part of the mathematical expression and should be treated as such (kept inside Nemeth switch indicators, uncontracted, with no single-word switch indicators).
Your use of the Nemeth general omission indicator is not incorrect, but it is not necessary. You could use a Nemeth shape to represent the print shape that indicates omission (Nemeth Code, section 115.b)