Files are stored in the Portable Grey Map (PGM) format. This is a simple flat file binary format preceded by an ASCII (readable) header that contains information such as the image dimensions and version number.There are 3 files for each day i.e. one data file (*.2bt) for the CLAUS Brightness Temperature Image Data and two ancillary files: *.2cs for CLAUS Contributing Satellite Image Data and *.2iq for CLAUS Interpolation Quality Image Data.See PGM File Format explained documentation under Docs.