We are starting to get serious about ePDM here, and are nearing the release of some newly developed products which we managed with PDM for the first time. We went with a separate workflow for product development vs production. The idea being that we start out in the DEV workflow with concepts, then prototypes/lab testing, then field validation. What ultimately makes it into production will move into the "ECN Release" workflow. (ECN process with ePDM is worth a forum all its own, it seems.)
In the product development process, it's reasonable that not all of the files will "make it" to be production part numbers. As we follow 5S principles in our company, I would like to encourage engineers who are wrapping up projects to clean things up. Release what is going into production, delete what is not worth keeping.
Then I can see a 3rd classification to the effect of *won't go into production, but maybe useful for future reference*. If we had some form of clear classification, the files themselves will serve as a "checklist" to make sure nothing got missed. These files would be likely candidates for cold storage.