What is Funny Looking at the list Jim Follis pointed out, unless I missed it, there is no country including Swaziland that uses what would be my obvious choice for Switzerland ( SW)

Then I noted that the suffix for the Cayman Islands is KY
I'm just wondering how much mail destined for Bowling Green KY winds up in the Cayman Isalnds
In most cases, I take the extra 10 seconds and just spell it out
Call me old fashioned but my mail gets there.

Some of these I understand like ES for Spain Espana
or EE for Estonia Eesti but others have me baffled as they make no sense at all

I guess it's no worse than some of the airport designations