[jameshart]

Very briefly worked in a metal fabrication shop in the last gasp of pre-CAD and electronic records. Writing out the bill of materials (by hand, to be typed up) involved a lot of numbers - measurements, quantities, and prices.

Using symbols like # before a quantity, @ before a unit price, or ⌀ before a diameter was considered critical for minimizing confusion. I think it was meant to work like a sort of Hungarian notation for numbers, so if someone’s transcribing them into an order form or something, and they find themselves copying a diameter into a price column, they catch themselves on the type mismatch.

It never seemed like there was much room for ambiguity in any of the lists I wrote up, but I guess when you screw up an order to a steel supplier and get the quantity mixed up with the length, that can be a pretty expensive mistake.