They have tried to get answers that avoid concepts that have not yet been introduced in the book at the point of the excercise, and to categorize answers based

They have tried to get answers that avoid concepts that have not yet been introduced in the book at the point of the excercise, and to categorize answers based on how well they do that. See http://users.powernet.co.uk/eton/kandr2/name.html http://users.powernet.co.uk/eton/kandr2/name.html for details. After over a decade, there's still excercises there that have no answers. That's a shame. (On me, I only provided a couple of them.)