That just means == is a "lossy" equivalence relation. I rather the precision be truely observable----every number is "infinite precision". Once can always include natural as extra field if one cares about empirical precision.
I'm having a bit of trouble parsing this, but Ion decimal values are not "infinite precision". Every decimal has a very specific, finite precision. It's a standard "coefficient and exponent" model, with no specification-enforced limit on either.
