It's common to discover that my publication database includes preliminary versions of research that are later incorporated in a book. I often cover these out of order. (To the extent that I have any order at all.) But in this case, the present article discusses some of the background considerations for Boag's book and adds to understanding it, rather than being redundant. (I have a few articles coming up that ended up being redundant and I've largely simply cross-referenced them to the more complete versions.)