I used to work in manufacturing a long time ago and when things got slow we would do random QC
I'd grab a box of parts, pull up the blueprint and see if everything was within spec
One day grabbed a skid and pulled up the print
And of course there is a date on the print and this little "revision" box on the bottom
(Now, usually revision boxes add info or tell you when things are changed for whatever reason)
This print literary said "revision A: print changed to match parts in stock