XDSi: a graphical interface for the data processing program XDS

With the ever-increasing automation of protein structure solution by X-ray crystallography, data collection and processing are the last experimental steps that can affect the quality of the data and, thus, the quality of the eventual model. For several dif®cult cases, such as high crystal mosaicity, the data processing program XDS (Kabsch, 1993) has proven to perform exceptionally well. However, especially for beginners, such as students learning both crystallography and the Unix system for the ®rst time, the use of the program has often been dif®cult. All user input is written to a single detector-speci®c input ®le, which ®rst has to be retrieved from a separate directory, using a text editor, and the program is started from the command line. In addition, in order to view the output, shell windows or text editors have to be used. In problematic cases, successful processing generally requires a number of runs, with editing input and examining output for each cycle. This can be frustrating when one has to run the program over and over again in a dif®cult case. Furthermore, the conversion of the XDS output re ̄ection ®les into a format recognized by the popular crystallography package CCP4 (Collaborative Computational Project, Number 4, 1994) is not straightforward.