Tortoize validates protein structure models by checking the Ramachandran plot and side-chain rotamer distributions. Quality Z-scores are given at the residue level and at the model level (ramachandran-z and torsions-z). Higher scores are better. To compare models or to describe the reliability of the model Z-scores jackknife- based standard deviations are also reported (ramachandran-jackknife-sd and torsion-jackknife-sd).