The 4MOST–Gaia Purely Astrometric Quasar Survey (4G-PAQS) will carry out the first large-scale, colour-independent quasar survey selected solely on the basis of astrometry from Gaia. Our main objective is to quantify the selection effects of current colour-selected samples. These colour-selected samples bias our view of the neutral gas and its

This a major release with a significant change of the sampler. It is now able to correctly sample likelihood functions with plateaus, (i.e likelihood functions with areas where likelihood value is exactly the same). The previous behaviour also led to inaccurate log(Z) estimates if some fraction of the prior volume had log(P)=-LARGENUMBER