e precision values, which is what Python float maps to
      on most boxes).

      In general, FLOAT cannot be used to transport infinities, NaNs, or
      minus zero across boxes (or even on a single box, if the platform C
      library can't read the strings it produces for such things -- Windows
      is like that), but may do less damage than BINFLOAT on boxes with
      greater precision or dynamic range than IEEE-754 double.
      ZBINFLOATZ