[Cfp-interest 2877] Re: TS-4r and TS-5r changes

[David Hough CFP]

Probably the most important sub-exceptions, that you wish weren't bundled
with other things, are signaling-nan and exact-underflow.   If you want
to try to do something useful with signaling nans, you don't want to have
to sort them out from invalid exceptions due to arithmetic issues.

And if you want to avoid losing precision by keeping numbers in mid-range,
you might want to catch even exact underflows are rescale.