There's something even worse... 0201, 0402, 0603 are all codes for SMT component sizes... and they mean something different depending on whether they are metric

There's something even worse... 0201, 0402, 0603 are all codes for SMT component sizes... and they mean something different depending on whether they are metric or imperial. 0201 imperial is 0603 metric. Most parts were imperial IIRC until at some point they started selling parts that were too small (smaller than 0201) and switched to metric. I can understand wanting to switch to metric, but reusing the same goddamn size codes is too chaotic for my taste. Come up with different numbers. You'll still use metric, but you'll just end up seeing lots of 2.54 or 0.254 everywhere.