: bridging the gap between small-molecule and macromolecular refinement.

The open-source Python program is designed to prepare a .ins file for refinement with [Sheldrick (2015). C, 3-8], taking atom coordinates and other information from a Protein Data Bank (PDB)-format file. If is provided with a four-character PDB code, both the PDB file and the accompanying mmCIF-format reflection data file (if available) are accessed via the internet from the PDB public archive [Read (2011). , , 1395-1412] or optionally from the server [Joosten, Long, Murshudov & Perrakis (2014). , , 213-220]. The -format .ins (refinement instructions and atomic coordinates) and .hkl (reflection data) files can then be generated without further user intervention, appropriate restraints . being added automatically. was tested on the 23 974 X-ray structures deposited in the PDB between 2008 and 2018 that included reflection data to 1.7 Å or better resolution in a recognizable format. After creating the two input files for without user intervention, ten cycles of conjugate-gradient least-squares refinement were performed. For 96% of these structures and completed successfully without error messages.