-1
Thanks to your question, Katie.
I don't think it is referring to the "built in open and close" functionality. It just explains what will happen when you wrap your heading text(it has a submenu UL that follows the heading text) with <a href="..."> ... </a>.
But if you want to override this so that the submenu under the heading will be in a close state, then you are right because you must use the "built-in open and close" functionality to accomplish that.
Sorry I don't quite understand what "the mark up to target the sub sub menus under the open header" means.
Actually I tend to think we should not allow the heading to be wrapped with an anchor tag. That makes life easy and we can get rid of the confusing stuff that we are discussing now. Do you agree with me?