I believe that SRFI 146 should be simplified to provide a guarantee of ordered immutable mappings.  The two cases users really need are ordered immutable and unordered mutable, and SRFI 125 provides the latter.

-- 
John Cowan          http://vrici.lojban.org/~cowan        xxxxxx@ccil.org
If you have ever wondered if you are in hell, it has been said, then
you are on a well-traveled road of spiritual inquiry.  If you are
absolutely sure you are in hell, however, then you must be on the Cross
Bronx Expressway.  --Alan Feuer, New York Times, 2002-09-20