That was the first CAD program for ID that I used, circa 1997. It was a stand-alone (at the time) partner to Pro/E. It ran on a crazy expensive Digital machine with top-of-the-line performance. I changed jobs from a pretty fun agency to a dysfunctional corporate gig just to use that software, and learned it quite well.
Isn’t CDRS essentially what became ISDX and then Wildfire?