[Cfp-interest 2937] Re: TS-4r augmented arithmetic terminology

[David Hough CFP]

If we were starting from scratch, "upper" and "lower" might have better
choices than "head" and "tail"
but it hardly seems worth changing.

"value" and "error" is definitely misleading.    The sum of the head and
tail is the (represented) value and the error would be the difference between
that and the true value, whatever that might be.