An enquiry came in last month for eleven sizes of fibre washer. A clean list, a drawing number against every line, quantities, the lot. Better than most we receive.
Two of the lines carried the same drawing number with different dimensions.
We could quote both, and we did. But we could not cut either, because one of them is wrong, and the drawing number is the only thing that ties our washer to their assembly. Cut the wrong one and it passes our inspection perfectly, because it matches exactly what we were told. It fails at their incoming inspection, or worse, on their line.
This happens more often than you would think. A drawing gets revised and the old size survives in somebody's spreadsheet. A line gets copied from one list to another and the number comes along without anyone checking the dimensions.
I do not point these out to look clever. The cost of asking is one email. The cost of not asking is a few thousand washers nobody can use.