Please follow the steps:
1. Edit->Preferences->Units & Display performance... to bring the dialog.
2. In "Units" group, we can change units for "General", "Stroke", "Type" and "Asian Type".
We can use AIUserSuite::GetUnitsString to get the general units, but how to get the other three units? Does anybody know it?
Interesting, I don't see anything in the API for doing that. Unless someone can find it squirreled away somewhere, it looks like there might be a hole in the API where this is concerned.