> Your confusion is understandable, since the Wikipedia article doesn't even make the slightest attempt to explain the diagram.
A little meta, but in these situations I usually try to improve the source and post a reply saying I edited it, instead of explaining it to one (or a few) person(s) here. Not saying it was bad that you just wrote a big comment explaining it completely! Just an idea of equal effort while reaching more people :)
That's very good advice, thanks for the reminder. I do edit Wikipedia fairly often, but didn't feel like I had enough time to do a creditable job on this topic this weekend. So consider my HN comment a rough draft of an upcoming Wikipedia edit.
A little meta, but in these situations I usually try to improve the source and post a reply saying I edited it, instead of explaining it to one (or a few) person(s) here. Not saying it was bad that you just wrote a big comment explaining it completely! Just an idea of equal effort while reaching more people :)