The "only" files extension permissible when saving a file "is" the ".rsd" extension. I suppose we need to figure how to show "only" the "RSD" instead of making it blank.

If you want to be on the "safe side" simply ADD the extension when you save it...
        IE: "MyFilename.RSD" 
                instead of using just
            "MyFilename" (no extension)

And, as you are asking.... you can name the same file that is present in the grids any or as many different file names as you like.

Thanks, I'll read through the addendum manual.
I do have one last question.  I'm not sure how to save the file as a RSD ext.  When I go to save something it has RSD as the file name, but under the "same as file type" it is blank with nothing to highlight.
Do I give it any name I want and then save it as a RSD.ext?  If so, exactly how is the file type written?
Thanks for you help.