On Mon, Oct 22, 2018 at 1:54 AM Mark H Weaver <mhw@netris.org> wrote:

This means that TAI-UTC = 4.2131700 + (MJD - 39126) * 0.002592, where
MJD is the modified julian day of the desired TAI-UTC delta. In this
case, the MJD (modified julian day) of midnight UTC January 1, 1970 is
40587, and plugging that into the equation above yields TAI-UTC =
8.000082 seconds.

Thanks. I have changed the errata list, the R7RS source (in the "errata" branch), and the cached copy of r7rs.pdf.