From: xxxxxx@angrygraycat.com
   CHAR-{UP,DOWN}CASE can work correctly as-is in Unicode as long as the
   program is working with decomposed character input - the most common
   case.

Heh? What about Latin-1's es-szet? Decomposing turns it into "ss" for sure?
Or leaves it as es-szet?

What is done with downcasing Unicode's position-sensitive Greek letters?

I think the sleazes I specify for patching CHAR-{UP,DOWN}CASE are acceptable,
but they are sleazes nontheless:
    - CHAR-UPCASE maps es-szet to es-szet.
    - Position-sensitive Greek letters get mapped to the general, non-final
      variant.
(And since these two procs are *not* part of SRFI-13, it's a side issue,
though one worth discussing.)
    -Olin