Under Windows, you iterate the characters and use AscW() to get the value:
if greater than 127, you've got a Unicode value. Sadly, to quote the
documentation, --

Visual Basic for the Macintosh does not support Unicode strings. Therefore,
AscW(n) cannot return all Unicode characters for n values in the range of
128 - 65,535, as it does in the Windows environment. Instead, AscW(n)
attempts a "best guess" for Unicode values n greater than 127. Therefore,
you should not use AscW in the Macintosh environment.