A prize should be offered to anyone who can explain, logically, how we (and even more surprising Grahamw48) managed to deviate so far from the question which Graham started this thread with !!!!!!
It is unfortunate that so often a question, which has been posted by a person really wanting the answer to that question, get left behind whilst we meander here there and everywhere, getting always further from the question. Thus, the thread-starter probably fails to get the answer they were hoping for. This gets increasingly worse as the thread grows longer, as probably most of us never go back and the read the first post, and all the subsequent ones.
Typically the problem Edward De Bono poses when he talks about 'digging holes to solves problems.' (Briefly, as the hole grows everyone forget why it was started and maintaining the hole becomes the reason for its existence).
PS I apologise or deviating !!!!