 Have just had a closer look at the way you joined the refs together. It looks ok on the surface, but you have obviously assumed that because two refs were side by side, they must be about the same point. This isn't necessarily the case; as I said before, sometimes two refs were about two different points, so there's no point joining them together.  In future I'll keep the refs separate so no-one will be tempted to join them up.  This ends my participation in this discussion. From now on, you have it all to yourself.  