I was happily trying to draft out something for my sup to see last night... then I realise that something that I assume that it's right is actually wrong... I need to mail them the drdft by today! I think of easy way out but I couldn't..... in the end I gave up, today i discuss it with people here... and they seem to mean that it's no big deal... just add in the n^a term in front.... it doesn;t look good now.. Mr BLOG