The pictures are in the post.
Thanks for the explanation. That makes sense. I was wondering whether I could fit them on my dadbike/shopping hauler, which I like to have to adjust as little as possible. Currently it's got Shimano LX V brakes with the parallelogram mechanism, which means that they can just be adjusted with the barrel adjuster as the blocks wear, with no change in pad position on the rim. The problem is that they squeal like crazy without massive toe-in. I thought arch rivals would provide the same fit-and-forget function, but obviously not.