I vote no.
The motion implies an internal format must be the same as a supported
interchange format. For example, if the interchange format is comprised of
two IEEE 754 values, then any implementation using extended precision,
multi-precision, or exact (symbolic) precision as an internal format would
be non-conforming.
Perhaps this is not the intention of the motion. But in that case, the
distinction between "supported" and "available" interchange types is
irrelevant. I would vote yes if all references to this distinction were
removed, leaving the standard silent on the internal format except to say
that all conversions preserve inclusion isotonicity.
Of course, an implementer may choose an internal format that is the same as
the interchange format. In this case, conversions are exact. However, I
think it is unreasonable to require this for all conforming
implementations.
Nate Hayes
Sunfish Studio, LLC