That does seem to be the question that resolved it eventually, but not the way I would have asked it. I would have started with "What is 'O' mode?" and, depending on the answer they came up with, I could have been thrown off course. Alternatively, another initial question I am likely to use when getting a report like this is to ask "What does it do when it doesn't work properly?", which could equally have given me a red herring.
Biting the hand that feeds IT
