Thank-you jana for BA and thanks to Danny for his honesty. I must say it was an intriguing problem; I felt my 50+ years of working with computer should have supplied me with the answer but my main experience was with FORTRAN and a couple of other languages unique to our workplace, whereas "Wrapper" seems to be associated with UNIX with which I don't have a lot of experience. My dozen years of retirement away from serious computing didn't help either. I suspect that TTT would have got there quicker than me but we don't see him much in "Quizzes".