Hi, I was attempting simultaneous x-ray and neutron refinement (5PTI from pdb, the neutron data are flagged there as FOBS-1). Both x-ray and neutron data were deposited; however, only x-ray data were recognized by phenix.refine. I worked around the problem by extracting neutron data into a separate .mtz file. New R-free flags had to be generated for neutron data. After the first refinement I ended up with xxx_data.mtz (attached), in which both Fobs and R-free flags for both x-ray and neutron data are specified. However, phenix.refine GUI still does not recognize the 'neutron' part of the input. In order to proceed with newly-generated r-free flags for neutrons I was forced to extract neutron data into separate file and neutron r-free flags into yet another separate file, read-in both additional files into the GUI and then specify from a drop-down menu what each of the files contained. Is there any way for phenix to read in all four coefficients (Fobs, neutron Fobs and associated R-free flags) from a single mtz file? Regards, Anna Makal PS: I was using PHENIX dev-1280 version.