Dear Barry, re. your 'Sorry' - No apology needed... My message was convoluted too. What I was trying to say (I used 'Spellcheck' and inadvertently deleted part of my message to Jack in reply to his request for challenge by us) is that the way he expresses his ideas impedes comprehension. King regards - I hope I have made myself clear now - Sarah PS I won't embarrass Jack by detailing where I see obscurity - maybe his students can help?