A couple of useful things to know about DC and CAL files and also how you can use both in the DC Editor if you want a nice and easy way to review the data
When SCS900 was created we created the Site Calibration process and adopted the DC file as our standard since that was the standard used by Trimble Access at the time and something everyone knew and understood. In the SCS900 use case, for construction purposes we determined that the thing for contractors was once the calibration was completed, that it would be locked down so it was not something that could change any time - since changing the Site Calibration would effectively change the position and elevation of every measured or staked location on site.
To meet this goal - in SCS900 when you measure points as a part of the Site Calibration we record all of that data in a .CAL file, and when you have done your Calibration calculation and accepted residuals etc, we write out a DC file that contains just the result of the Site Calibration. The DC file in SCS900 is seen as the "Locked version of the calibration. This is quite a different approach to say trimble Access where any time in the Job file you can add new control or make additional adjustments to the residual analysis and update a Site Calibration because that also updates all of the derived coordinates (however it doesn’t move the stakes to the new correct position of course - those stay in the ground where you left them (provided a machine did not knock them down in the meantime …).
So what is the difference between a CAL and a DC file. The answer is only the file extension and in the SCS900 / Siteworks use case the CAL contains the measurement data (the point pairs) whereas the DC file contains the result. Both the CAL and a DC file are basically a DC file.
The next question is then “why can’t I open a CAL file in the DC File Editor”?.
The answer to that is you can - open the DC File Editor, go to File, Open and in the file selector dialog select the option for All Files of All Types. That will display the CAL file, you can select it and it will open and look just the same as a DC file would look in the same editor. You could also rename the CAL file to a .DC and that would allow you to also open it as a DC file.
Hope that this is helpful