Setting a multi-line `notesPlain` value on an edited item

So I want to clarify something about the notesPlain field; as long as what I have does not have newlines in it, I can easily edit notesPlain. The moment I have newlines in it, only the last line shows up. While it will be wonderful to have a general --notes field that automatically sets that, I want to make sure that I can add a multi-line note with no problem, either by --notes $(cat notes.md) or something with encoding (such that the character pair \n becomes newline or something like that), or maybe with a --notes-json that allows a JSON-encoded string that then gets decoded into the multi-line version.