Screenshot of SrRietveld's plotting window during a sequential refinement. The data are for NaCl and were measured as a function of temperature (see §3 for details). The top-right panel shows the fit of the data set being currently refined. The crosses are the data, the solid red line is the calculated pattern and the green line offset below is the difference curve. The black tick marks show the positions of Bragg peak reflections in the model. We have chosen to monitor the a lattice parameter values (bottom-left panel) refined from each of the data sets. The values of the fits are shown in the lower-right panel, allowing issues to be addressed as they emerge. Text outputs from the program are displayed in a text window that is just evident in the lower left of the figure.