I'm no expert and this may be a question that the true answer may never be "proven". If it is an identification mark, you would expect this to be added at the start of the dies life and therefore for more examples of the same date/spot to be known. It would also be human nature to put them in a logical position eg in the legend or at 12 o'clock 6 o'clock etc.If it is a random foreign body to blame, then this could presumably happen at any point in the life of the die, so some varieties should be a lot more common than others depending on how far through the life of the die the damage occurred. Also as the flan is much softer than the die is a foreign body more likely to embed itself into the coin rather than the die when struck?If it was an attempt to stop a die flaw / crack from becoming worse, then this is more likely to be towards the end of the dies life making examples fare scarcer. Is it also possible that the die could show a sign of failing and a remedy be applied before it would appear on coins struck explaining why Brian's coin has a dot but no sign of a flaw, but this also suggests the drilling or punching of the die, didn't stop the deteriorating further. Or maybe there could be another explanation?It would be interesting to see if these dots appear on all denominations in equal proportion to the number of coins minted. Trying to establish a time line of coins produced by the same die showing dot or no dot flaw or no flaw may help in identifying a reason but may be impossible to do. Is silver not the "shiny side" rather than the "dark side" Hopefully Brian, but silver collectors may be reading the title and passing over the thread mumbling under their breath about pesky penny collectors Ian..