a program that carries out rigid body, tls, restrained or unrestrained refinement against Xray data, or idealisation of a macromolecular structure. It minimises the coordinate parameters to satisfy either a Maximum Likelihood or Least Squares residual. It also produces an MTZ output file containing weighted coefficients for SigmaA weighted mFo-DFcalc and 2mFo-DFcalc maps, where missing data have been restored.