1.  I believe that every numerical value should have an external
representation.  There are many different NaNs (the only requirement
is that the biased exponent field should be a maximum and the
mantissa field be nonzero), so it should be possible to specify or
determine this information about a NaN from its external representation.

2.  If Scheme really wants to get serious about floating-point
arithmetic, one should be able to specify the precision of floating-
point operations.  "One-precision-fits-all" doesn't cut it for
serious code.

Brad