The .CAL gives you all of the data - if you ever have to check or change the SIte Cal you would need this file
The .DC gives you the Result data of the calibration which is all you need to set up the machines
Either file works
If you have any GCS900 machines on site the .CFG file will also work
If you have Survey Controller or Trimble Access doing the Site Cal then the JXL file (Job File) is what you would need from them
Alan