0603 case size on Arduino UNO. Metric or Imperial???

I'm working on a variant of the uno. hopefully I'll get to make a batch of them but the details are a secret :slight_smile: anyways I'm putting together the parts list and I had assumed that the case sizes I was seeing were in mm but I've only ever seen the board layout dimensions in MILS so now I'm thinking that the case sizes are 0603 inches. so anyone know for sure?

Pretty sure it's inches (hundredths of an inch.) 0603 imperial is 1608 metric, a standard SMT size that about matches the footprint. 0603 metric is 0201 imperial, which is REALLY TINY.

I like using this as a reference: