Constraints on the Hubble constant and selected parameters in model B assuming independent scales of host-galaxy interstellar reddening τ and scatter σ_MB in the young supernova population of the Hubble flow and the calibration galaxies, and a fixed, Milky Way-like distribution of R_B in the calibration galaxies. The best-fit model demonstrates a reduction of the Hubble constant due to a larger reddening scale in the calibration sample than in the HF (τ_cal > τ_y, HF). The contours show 1σ and 2σ credible regions containing 68 and 95 per cent of 2D marginalised probability distributions.