*.dm4 are DigitalMicrograph data (proprietary software from Ametek/Gatan)
*.emd are Velox-data (proprietary software from Thermofisher/TFS)
*.mrc are tomography data, readable with Velox or ImageJ
*.gfrm and *.brml data are are originally generated from the Bruker D8Discover diffractometer using the measurement software DIFFRAC.COMMANDER; they can be opened by DIFFRAC.EV (https://www.bruker.com/en/products-and-solutions/diffractometers-and-x-ray-microscopes/x-ray-diffractometers/diffrac-suite-software/diffrac-eva.html) software from Bruker
all data without extension can be opened with a text-editor