I just noticed that I cannot edit my own posts any more. I don't know if edits are now only for a limited period, but if it is, I feel it is too short. The reason is, occasionally other replies make clear that the advice I have given is perhaps less than I ought to have given in the first place, or more often, I find my original expression can be simplified or expanded for greater clarity. (Especially spelling or punctuation or ambiguity boobs). This can happen a week or more later, but I still like to improve my original post with a view to helping other people coming across it at a later date.