Rationals

Following the discussion of rational numbers I haven't found any
reason to support lexical rationals versus a datatype. However I have
some questions about conformance and implementation burden.

1) What is the proposed minimal conformance, i.e. what rational
literals are core literals?
2) What are the implementation requirements for core rational
literals? One needs to be able to both compare rationals to other
numeric datatypes as well as compare them to each other. Analogous to
the issues we discussed with implementation of rational numbers, how
does one implement a satisfiability test for  r1 < f < r2 where r1 and
r2 are rationals and f is a floating point number?

Note: Implementations of rational numbers I'm aware of use arbitrary
precision arithmetic. As I recall, the reason we did not require
arbitrary precision integer arithmetic for minimal conformance so as
to avoid the necessity of all implementation using such.

Thanks,
Alan