OneMileHigh, Ooizcalling, thank you for your replies! Iīm sure itīs a lot of help for my friend.
I will try and persuade him to post the results of his search when he is finished with it. It may take a little while, though; thanks in advance for your patience.
Again, thanks a lot for your help!
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You canīt make it foolproof.
Fools are too inventive.