  The uncertainty for calibrating $100$ M$\Omega$ and $1$ G$\Omega$ resistors
using the NPL high-resistance CCC bridge has been re-evaluated, resulting in
combined uncertainties of $\sim 0.1$ $\mu\Omega/ \Omega$, considerably smaller
than the CMC entries of $0.4$ $\mu\Omega/ \Omega$ and $1.6$ $\mu\Omega/ \Omega$
respectively. This re-evaluation supports measurement of single electron pump
currents with combined uncertainties of a few parts in $10^7$.
