Interesting book written by the man who knows and as accurate as would be possible within the confines of the OSA. Well worth the read but a great pity that sales did not make it clear that this and the second book purchased under the same main but different subtitles are in fact exact reprints of the original work ie the different main sub title descriptor led me to believe these were two different works by the same author covering the same subject. Oh well I have a second copy to give away. Trouble is ~ one was eight times the price of the other which also helped send me off on a false trail.