Question Re: Per Diem and Int'l override

[RIP]

For those of you who get an Int'l override for per diem, how does it work?

More specifically, lets say you start in CLT and do a round trip to CYYZ, followed by a leg to DTW and then overnight in DTW. Do you get any international override here, or is it only when you actually layover in an Int'l city?

Thanks