OK but that may be a less common case of people
seeing chords as opposed to just improvising (back to the
learning vs reading thread!). I tend to think of the more common scenario of improvising based on knowing or just hearing the harmony. There are plentof examples of Charlie Parker playing an 11th on a dominant and not just as a passing note which I think everyone would agree is within the conventional rules.
I don't think I've ever come across that chord symbol, but a quick search shows that many people (and even AI
🙂) thinks it includes the 3rd.
Regarding avoid notes, In my own teaching I don't advise bothering with the concept. It seems to be something coined by Jamey Aebersold and the chord/scale syllabus which as many of you know is something I eschew. (Originally I did buy into the concept when I took over from another jazz theory lecturer at UOS)
I just checked TTS2 and found I'd written this: