I don’t know quite where or how to suggest this “formally,” but I would like to suggest that all the little various icons and symbols in places like the Dope Sheet, Outliner, should have pop-up explanations that appear when you hover the mouse over them. Many other interface icons already have this feature, and it is priceless. But the editors generally do not seem to have it.
If you already know what a tiny icon means, it’s an instant and informative reminder. But, if you don’t . . . or if you just don’t remember . . .
I think that this would be very-easily added to the Blender code and it would be a huge(!) help for me.