Cheat sheet

In the following, I describe the steps that I typically do in my processing workflow. The links given in the form XDSGUI#Frame refer to the XDSwiki at https://wiki.uni-konstanz.de/xds/index.php/ (in this example https://wiki.uni-konstanz.de/xds/index.php/XDSGUI#Frame ). I assume that the programs have been properly installed - see Installation. Troubleshooting hints are at Problems.

Action	why? what to look out for? what else to know?
1. open a terminal and move the window to the left side of the screen. If you work with HDF5 data, now type export NEGGIA_PATH=/usr/local/lib64/dectris-neggia.so - the path must match YOUR computer; the path given is just a typical one. Type xdsgui and move its window so that you still see the left half of the terminal window.	Keeping the terminal window to the left of the XDSGUI window makes it possible to see some screen output of XDSGUI, e.g. error messages, or the pointless output. For HDF5 data from DIAMOND, use export DURIN_PATH= /usr/local/lib64/durin-plugin.soinstead (of course with the correct path). The actual path must appear in "Generic frame library" under Preferences, on macOS, or Settings, on Linux, and should appear after LIB= in XDS.INP (below). Optionally, before typing xdsgui : cd to an existing XDS directory, or create a new (empty) directory:cd <toplevel-directory>;mkdir <xds-directory>; cd <xds-directory>
2. click the Projects tab and either choose an existing entry (if there is a list of previous projects) or browse to an existing XDS directory, or create a new (empty) directory	If XDS's files already exist in the XDS directory, their content is shown in the tabs of XDSGUI. Note that the XDS directory name appears in the title bar of the XDSGUI window!
3. click the Frame tab and load a frame of your dataset (for HDF5, load xxx_master.h5). Click generate XDS.INP - this reads the header of that frame, and counts the frames of the dataset. Use Zoom, Contrast and Brightness and move around the frame to evaluate the shape and separation of the reflections: are they smeared or sharp, tiny or broad, regular or broken, symmetric or asymmetric? Look at other frames (selector is at upper right of window) as well!	Watch the green crosshair at ORGX ORGY, the green circle around it (lower INCLUDE_RESOLUTION_RANGE), the red UNTRUSTED_RECTANGLEs at the module borders, and the blue TRUSTED_REGION appear. The corresponding keyword=parameter lines in XDS.INP have the same colour code.
4. mask the shaded regions of the detector: at least the beamstop shadow, and the beamstop holder. There is a button Untrusted areas (...) towards the upper right with three tools: UNTRUSTED_ELLIPSE, UNTRUSTED_RECTANGLE, UNTRUSTED_QUADRILATERAL	This step is important, do not forget it! Reason is in the XDSGUI paper (reference at the end). More explanation of the tools is at XDSGUI#Frame . Wrongly placed UNTRUSTED areas can be removed by deleting their lines in XDS.INP .
5. click the XDS.INP tab and inspect its contents. For a first XDS run, typically you would leave everything at its defaults, except with broad reflections covering many pixels, set MINIMUM_NUMBER_OF_PIXELS_IN_A_SPOT to 6 instead of 3.
6. click Save (unless greyed out) and Run XDS and watch the adjacent tabs to the right flash yellow as they are being filled with text and graphics. Inspect the left (text) and right (graphics) sides of the tabs.	If XDS stops after the IDXREF step (with ERROR in IDXREF.LP), this most often happens because it could index less than 50% of the spots only. This may be due to ice rings that obviously cannot be indexed, or due to additional lattices. In most cases, this should at least prompt you to think about the possible reasons. To continue, set JOB=DEFPIX INTEGRATE CORRECT in the XDS.INP tab, Save and Run XDS.
7. once IDXREF has run, inspect the predictions in Frame . Even better: in tools go to the second item in Further analyses and open Coot by clicking the button. It will load the indexed reflections (yellow) and non-indexed ones (pink) as pseudo-PDB files into Coot. Inspect the lattices: is the "yellow lattice" convincing, and/or do the pink reflections form their own lattice(s), or are they just random?	similarly, inspect the tabs- COLSPOT: is the "number of spots" evenly distributed among the frames? If not, it may be a sign of radiation damage or anisotropy, or plate-shaped crystal. COLSPOT IDXREF: are the "CLUSTER INDICES" of the difference vectors integer numbers, or close to integers? Are the cell parameters reasonable? Is the first POPULATION of the first SUBTREE close to 3000? See IDXREF.LP and IDXREF .
8.

The XDSGUI paper (Brehm, Triviño, Krahn, Usón and Diederichs (2023) XDSGUI: a graphical user interface for XDS, SHELX and ARCIMBOLDO. J. Appl. Cryst. 56) is open access at https://doi.org/10.1107/S1600576723007057 .