Alan Kay takes part in discussion here occasionally. He seems like a pretty easygoing guy (but you might want to reign it in a bit) so you could probably just email him...
To be clear, you mean 90%, correct? If so, the ÷ symbol (which I just learned is called an obelus) is typically used for division—I've never seen it used to mean percent. Is this a locale difference? A keyboard issue? I've seen that Android users will sometimes mistype ℅ for % due to their proximity on a certain keyboard, for example.