> Windows uses some kind of case-insensitive, but not case-folded, undocumented early 1990s UCS-2 sorting logic for environment variables.

I strongly suspect that it ends up in something equivalent to `RtlCompareUnicodeString` with the `CaseInsensitive` parameter set to `TRUE`. (Or at least, some functionally-equivalent copypasta.) That function is old enough that it almost certainly doesn't do anything right or proper or culture-sensitive when doing the comparison.

thanks,
john

Thanks, John, I think that's it! I tested my pathological inputs, and they 
all match get/set. I've updated the article with this information. This is 
exactly the sort of thing I was trying to find in my research.