" radio code" is problematic for number of reasons. One reason is that professionals and laypersons who must read your report wont understand ir, another is that:

Answer 1

You always need to consider who your reading audience is, every time you write anything. This handout explains it.
https://writingcenter.unc.edu/tips-and-tools/audience/

If you are looking for a specific word to fill a blank, however, you'll need to go back into your text or class notes.