Unable to retrieve folder revisions through /metadata using rev parameter.

Thanks for your answers Gregory. I was doing something similar and could see from the 400 code that was returned to me that I can't get the "revisions" for a folder. However, what can be done instead? I have a list of 730 folders. Anytime the name changes on one of them, I need to change the name of an item in a separate database. The problem is, without the revisions, I'm not sure how to get the OLD name in order to find the item to change in my connected database. I set up a poll for new directories under a given path, which will catch when folders are renamed, but it will only give me the NEW name, which isn't helping for finding the old value in my database to change it. (on top of this issue, the "new directory" poll will also catch brand new folders, instead of just those that are renamed, which causes other issues as well.) Could I get some help? Maybe "/delta" is the key, but not sure how to structure the solution in my case.