NADA is a computer program for the simultaneous refinement of the components of the orientation matrix and the components of up to three modulation vectors by the method of least squares. Using the spatial peak positions and the orientation matrix of the main reflections from a single-crystal diffraction experiment and rough estimates of the modulation vector(s) components, NADA re-indexes the peaks (main and satellite reflections) with integers in higher dimensions (hklm(1), hklm(1)m(2) or hklm(1)m(2)m(3), respectively) and refines the orientation matrix and modulation vector(s) components from the observed peak positions. Standard uncertainties on all refined parameters are calculated analytically. [References: 7] 7