I agree. This is only possible when all resource access flows from a predefined "root" resource via hyperlinks. If you're doing that, why force (arguably more d

I agree. This is only possible when all resource access flows from a predefined "root" resource via hyperlinks. If you're doing that, why force (arguably more difficult) accept header handling on your api clients? Then they have to set the accept header correctly at every request instead of getting the version number right once when retrieving the root document. Beyond that debugging now requires access to / a record of the accept headers involved, and returning the latest version for plain application/json creates a very nasty bug for clients. I don't think REST meaningfully comes down on either side of this idea. I do think practicality sits highly in favor of versions in URIs.