Using partial observations, partial models and partial residuals in least-squares refinement

ShelXle[1] is a graphical user interface for SHELXL [2], which is currently the most widely used program for small-molecule structure refinement.Since the first beta release in Februrary 2011 ShelXle has been downloaded more than 10000 times.It combines an editor with syntax highlighting for the SHELXL-associated .ins(input) and .res(output) files with an interactive graphical display for visualization of a three-dimensional structure including the electron density (Fo) and difference density (Fo-Fc) maps.Special features of ShelXle include intuitive atom (re-)naming, a strongly coupled editor, structure visualization in various mono and stereo modes, and a novel way of displaying disorder extending over special positions.ShelXle is completely compatible with all features of SHELXL and is written entirely in C++ using the Qt4 and FFTW libraries.It is available at no cost for Windows, Linux and Mac-OS X and as source code.