AMPTE/CHEM data are in daily FITS files. More info about the FITS standard and FITS readers is available through these links:
FITS files are organized according to a primary image and zero or more extensions. For historical reasons, all FITS files must start with an image. For AMPTE/CHEM, this image is empty -- all the data are in extensions after the required but blank image.
Each extension past the primary image is a binary table containing a time series of CHEM data records. These records have been translated directly from the VMS records. There are also some additional elements in the records in which some processing has been done to the data. These are cases in which the original values represented compressed information (necessary in the 1980's when storage was expensive), and the new columns in the table provide the decompressed quantities. For example, the count rates were logarithmically compressed into 8 bits. These values have been expanded using the proper lookup table, and the result stored in the online FITS files.