4 KudoZ points awarded for this answer. Comment: "Thanks, I thought about that, and where possible I have left it in full, but in places it appears very frequently and writing it in full sounds odd and repetetive, and in other places it's in a chart with lots of abbreviations. so would be make the columns expand and look less neat. In the end I'll think I'll for a combination of all the suggestions, ie in full where possible, and just IS elsewhere. thanks again for your suggesions. "