Thanks everyone for the responses to this photo. It demonstrates why I like threaded views for C&C rather than flat view. On this occasion, although we are in flat view, we have a development of ideas that can be followed. It can be done in flat view but it is difficult.
Here we have ideas that build on each other. I wouldn't have made the connections that develop through the responses. My appreciation of Open Cube's image is much better for the discussion.