@Penzancemaid is so right with the fact that it is a marker (my clues was going to be that it represented a long running battle).
But, which marker? This is one point over which I would disagree with Hayle.
@Penzancemaid - it saddened me to see it like this. It is one of a list of three things about which I intend writing to Hayle.
@symons55 - your book is overdue.
