For example, at the frequency threshold $p=0.5$\%, there are only 52 rare $p$-mutations in CP2 in the CAMP MAG, resulting in a mutation rate of $4.4 \times 10^{-5}$ for the decoy genome of just the CAMP CP2 positions (as compared to $6.4 \times 10^{-5}$ for the entire CAMP MAG). Using the CAMP CP2 positions as a new decoy genome, the estimate of the FDR for called mutations in the BACT1 MAG can now be reduced from 2.4\% to 1.7\%.\endinput